Aseptic technique is a method of compete elimination of microorganism, used in laboratories or clinical setting to prevent the contamination or growth of unwanted microorganism.
Pure cultures are important in microbiology for the following reasons:
Once purified, the isolated species can then be cultivated with the knowledge that only the desired microorganism is being grown.
A pure culture can be correctly identified for accurate studying and testing and diagnosis in a clinical environment.
Testing/experimenting with a pure culture ensures that the same results can be achieved regardless of how many time the test is repeated.
Pure culture spontaneous mutation rate is low
Pure culture clone is 99.999% identical
To maintain pure culture for extended periods in a viable conditions, without any genetic change is referred as Preservation. The aim of preservation is to stop the cell division at a particular stage i.e. to stop microbial growth or at least lower the growth rate. Due to this toxic chemicals are not accumulated and hence viability of microorganisms is not affected.
The material describes components of industrial fermentation media with their respective metabolic importance for the industrial microbes. it also addresses industrial scale sterilization methods.
hii
Presented on based on sterilization method in Bioprocess
definition of sterilization there types
importance of sterilization
application of sterilization
phy method ,chemical method ,mechanical method
.
Sterilization is the killing or removal of all microorganisms, including bacterial spores, which are highly resistant. Or It provides environment free from living micro-organisms .
There are various methods of sterilization which are discussed below :
Physical method
Chemical method
Biological method
A . Physical Methods of Sterilization:
Heat method of sterilization
Filtration
Radiation
.
Microbial Culture Preservation and its MethodsDENNISMMONDAH1
This document discusses various methods for preserving microbial cultures, including short term and long term methods. Short term methods include periodic transfer to fresh media, preservation using saline suspension, drying, and refrigeration. Long term methods discussed are preservation using liquid paraffin/mineral oil, glycerol, lyophilization (freeze drying), and cryopreservation in liquid nitrogen. The aim of preservation is to maintain cultures in viable condition for extended periods without genetic changes.
The document discusses various techniques for preserving industrially useful microorganisms. It describes serial subculture, preservation under oil, freeze drying, preservation in distilled water, preservation on soil, and preservation by liquid nitrogen. Serial subculture is the simplest method and involves regularly transferring microbes to fresh media. Preservation under oil prevents drying out using a mineral oil overlay. Freeze drying freezes and then dries cultures under vacuum to allow long term storage. Liquid nitrogen preservation at very low temperatures in a glycerol solution allows viable cultures to be kept for many years.
The document discusses inoculum development and production media for industrial fermentation. It defines inoculum as a culture of microbes used to inoculate production-scale fermentations. Successful fermentations require developing inoculum to an active, healthy state in appropriate density. The document outlines factors that affect fermentation and discusses various media components like carbon sources, nitrogen sources, and trace elements. It also covers inoculum development methods for bacterial and mycelial cultures, preservation techniques, examples of media used for specific inocula, and criteria for a good inoculum.
Food preservation methods aim to prevent microbial decomposition, self-decomposition, and damage from insects or animals. Key methods include preventing microbial growth through controlling factors like temperature, water activity, and pH. High temperatures can be used to pasteurize or sterilize foods through methods like canning. Drying and smoking also inhibit microbial growth by reducing water availability. Chemical preservatives interfere with microbial cell membranes and enzymes. Aseptic packaging, irradiation, low temperatures, and controlled atmospheres provide additional preservation techniques.
The material describes components of industrial fermentation media with their respective metabolic importance for the industrial microbes. it also addresses industrial scale sterilization methods.
hii
Presented on based on sterilization method in Bioprocess
definition of sterilization there types
importance of sterilization
application of sterilization
phy method ,chemical method ,mechanical method
.
Sterilization is the killing or removal of all microorganisms, including bacterial spores, which are highly resistant. Or It provides environment free from living micro-organisms .
There are various methods of sterilization which are discussed below :
Physical method
Chemical method
Biological method
A . Physical Methods of Sterilization:
Heat method of sterilization
Filtration
Radiation
.
Microbial Culture Preservation and its MethodsDENNISMMONDAH1
This document discusses various methods for preserving microbial cultures, including short term and long term methods. Short term methods include periodic transfer to fresh media, preservation using saline suspension, drying, and refrigeration. Long term methods discussed are preservation using liquid paraffin/mineral oil, glycerol, lyophilization (freeze drying), and cryopreservation in liquid nitrogen. The aim of preservation is to maintain cultures in viable condition for extended periods without genetic changes.
The document discusses various techniques for preserving industrially useful microorganisms. It describes serial subculture, preservation under oil, freeze drying, preservation in distilled water, preservation on soil, and preservation by liquid nitrogen. Serial subculture is the simplest method and involves regularly transferring microbes to fresh media. Preservation under oil prevents drying out using a mineral oil overlay. Freeze drying freezes and then dries cultures under vacuum to allow long term storage. Liquid nitrogen preservation at very low temperatures in a glycerol solution allows viable cultures to be kept for many years.
The document discusses inoculum development and production media for industrial fermentation. It defines inoculum as a culture of microbes used to inoculate production-scale fermentations. Successful fermentations require developing inoculum to an active, healthy state in appropriate density. The document outlines factors that affect fermentation and discusses various media components like carbon sources, nitrogen sources, and trace elements. It also covers inoculum development methods for bacterial and mycelial cultures, preservation techniques, examples of media used for specific inocula, and criteria for a good inoculum.
Food preservation methods aim to prevent microbial decomposition, self-decomposition, and damage from insects or animals. Key methods include preventing microbial growth through controlling factors like temperature, water activity, and pH. High temperatures can be used to pasteurize or sterilize foods through methods like canning. Drying and smoking also inhibit microbial growth by reducing water availability. Chemical preservatives interfere with microbial cell membranes and enzymes. Aseptic packaging, irradiation, low temperatures, and controlled atmospheres provide additional preservation techniques.
Microorganisms can have both beneficial and harmful effects, so controlling their growth and transmission is important. This document discusses various physical and chemical methods for sterilization, disinfection, sanitization, and antisepsis. Physical methods include heat (moist heat via autoclaving or dry heat), filtration, radiation, and low temperatures. Chemical methods discussed are phenolics, alcohols, halogens (iodine, chlorine), and heavy metals which were historically used but are now less common due to toxicity. The goal is to inactivate pathogens while minimizing harm to humans and materials.
1. The document discusses the production of lactic acid, glutamic acid, and cheese through fermentation processes. Lactic acid bacteria and fungi are used to produce lactic acid from sugars. Corynebacterium glutamicum is commonly used to produce glutamic acid from glucose through biosynthesis pathways.
2. The production of cheese involves pasteurizing milk, adding bacterial cultures, coagulating the milk with rennet enzyme, separating curd from whey, and ripening the curd through the action of molds and bacteria.
3. Specific microorganisms and fermentation steps are outlined for efficiently producing these three compounds at an industrial scale through microbial fermentation of sugars and carbohydrates.
Preservation of industrially important microbial strainAishwarya Konka
This document discusses techniques for preserving industrially important microbial strains. It describes methods where microbes are kept in a continuous metabolic active state through periodic transfer to fresh media, overlaying cultures with mineral oil, and storage in sterile soil. It also covers techniques where microbes are placed in a suspended metabolic state, such as drying in vacuum, lyophilization, cryopreservation in liquid nitrogen, and storage in silica gel. The goal of preservation is to maintain microbial cultures alive, uncontaminated, and as healthy as possible for long periods of time.
The document discusses various methods of food preservation including:
1. Removing or killing microorganisms through methods like asepsis, filtration, washing, and heat treatment.
2. Maintaining conditions unsuitable for microbial growth using techniques such as low temperatures, drying, smoking, and chemical preservatives.
3. Combining preservation methods, for example pasteurizing then refrigerating foods, in order to lengthen the lag phase of microbial growth and prevent spoilage. Proper food preservation prevents foodborne illness and significantly extends the shelf life of foods.
Fermentation is a process that uses microorganisms like yeast or bacteria to convert carbohydrates into organic acids, gases, or alcohol in the absence of oxygen. Fermentation is used in food processing to make foods like cheese and yogurt. Cheese is made through a process of standardizing milk, pasteurization, culturing, coagulation, draining, pressing, aging, and packaging. There are many types of cheese categorized by texture, aging period, production method, milk source, and moisture content such as soft, semi-soft, hard, and processed cheeses. Cheese provides nutritional benefits like vitamins, calcium, and protein but also has risks if consumed in large amounts like increased saturated fat, cholesterol, and potential allerg
This document compares submerged fermentation (SmF) and solid state fermentation (SSF). SmF uses a liquid substrate and is suitable for bacteria that require high moisture, while SSF uses a solid substrate and is better for fungi or bacteria that prefer less moisture. SmF allows for more control of parameters but requires more energy, while SSF is simpler and can use waste materials as substrates. Both methods are used industrially to produce compounds like antibiotics, enzymes, and organic acids.
This document discusses the airlift fermenter. It notes that fermenters must provide a controlled environment for microorganism or cell growth to produce desired products. An airlift fermenter circulates liquid using the density difference between the riser and downcomer columns caused by sparged air or gas. The main type discussed is the concentric draft tube airlift fermenter, which has an internal riser tube that introduces gas to lift liquid up the riser and down the surrounding downcomer tube. Tower loop and ICI deep shaft airlift fermenters are also mentioned. Airlift fermenters provide mixing without mechanical agitation and have high oxygen transfer rates, making them well-suited
This document summarizes batch and continuous sterilization techniques. It discusses that batch sterilization involves injecting steam or direct heating of media to reach 121°C for 20-60 minutes. Continuous sterilization operates at a higher temperature of 140°C for only 30-120 seconds. The document also reviews advantages and disadvantages of each technique, such as batch sterilization being more energy intensive while continuous sterilization risks precipitating certain compounds. Air sterilization methods like filtration and UV radiation are also summarized.
The document discusses the key stages and unit operations involved in downstream processing after fermentation or bioconversion. The main stages are: (1) removal of insolubles through filtration, centrifugation or sedimentation; (2) product isolation using techniques like liquid-liquid extraction, adsorption or ultrafiltration; and (3) product purification using chromatography, crystallization or precipitation. The final stage is (4) product polishing which includes further processing and packaging into a stable form.
The document summarizes the process of beer production. Malt is made from soaked and sprouted grains like barley. Mashing involves mixing malt with water and adjuncts like rice and corn starch. This allows enzymatic degradation of starch to sugars. The liquid produced is wort, which is separated and then fermented with yeast along with hops for flavor. Fermentation yields alcohol and carbon dioxide. The final beer is pasteurized, carbonated, and aged to improve flavor before consumption.
Food Industry of Biotechnology involves preparation of different food items that are used as common part of diet throughout the world.The presentation describes the Industrial preparation of Yogurt.
This document outlines a procedure for isolating microorganisms from a sample using the pour plate method. The aims are to isolate and obtain pure cultures of microorganisms. The principle involves diluting the sample and mixing it with warm agar which is then poured into petri dishes to form individual colonies after incubation. Colonies are then transferred to fresh media for identification. The procedure involves preparing and sterilizing media, diluting the sample, pour plating the dilutions, incubating, and recording results to determine the number of viable microorganisms present.
The document discusses methods for examining food and water microbiologically. There are three main methods discussed: culture media methods, immunoassay methods, and polymerase chain reaction (PCR) methods. Culture media methods involve culturing samples on selective and differential media to isolate and identify microorganisms. Immunoassay methods like ELISA use antigen-antibody binding to detect toxins and microbes. PCR methods amplify and detect targeted nucleic acid sequences to identify pathogens. Examining food and water microbiologically is important to ensure safety and determine processing parameters needed to meet standards.
Sterilization is a process that eliminates all forms of life through physical or chemical means. Media sterilization can be done through boiling, steam exposure, or autoclaving. Air sterilization is commonly done through filtration to provide a continuous supply of sterile air for aerobic fermentation.
Glycerol can be produced by using different processes and feedstocks. For example, it can be obtained by propylene synthesis via several pathways [8], by hydrolysis of oil or by transesterification of fatty acids/oils.
This document discusses various physical methods for food preservation, including ionizing radiation, nonionizing radiation, light, high pressure processing, pulsed electric fields, and modified atmosphere packaging. Ionizing radiation works by affecting nucleic acids and cell membranes, while nonionizing microwave radiation causes protein and nucleic acid denaturation. High pressure processing and pulsed electric fields disrupt cell membranes. Modified atmosphere packaging and vacuum packaging inhibit aerobic microorganisms by reducing oxygen levels.
Downstream processing refers to the stages involved after fermentation or bioconversion, including separation, purification, and packaging of the product. The key stages are removal of insolubles through filtration, centrifugation or flocculation, product isolation using techniques like liquid-liquid extraction or adsorption, product purification using chromatography or crystallization, and product polishing which prepares the product for packaging and storage. Downstream processing aims to recover and purify the target product from the fermentation or reaction broth.
The document discusses various methods for preserving microorganisms. Short term methods include periodic transfer to fresh medium, storage in saline suspension, and refrigeration. Long term methods involve storage under mineral oil, lyophilization (freeze drying), cryopreservation in liquid nitrogen, and storage in sterile soil or silica gel. Lyophilization works by freezing and then reducing moisture content through sublimation and desorption. It allows storage at room temperature for many years but can damage some microbes. Cryopreservation in liquid nitrogen at -196°C also enables long term storage of over 10-30 years without genetic change.
This document summarizes various sterilization methods used in hospitals. It discusses the aims of sterilization and differentiates between sterilization, disinfection, and antisepsis. It then describes various physical sterilization methods like heat, radiation, filtration and chemical methods like alcohols, aldehydes, phenols, and halogens. Specific sterilization techniques are outlined, including autoclaving, dry heat ovens, radiation, and chemical disinfectants. Testing methods for determining the efficacy of sterilization processes are also briefly mentioned.
Sterilization refers to processes that eliminate transmissible agents like bacteria and viruses. There are physical and chemical methods of sterilization. Physical methods include heat sterilization like autoclaving, which is the most widely used method, as well as radiation and filtration. Chemical sterilization uses gases like ethylene oxide and formaldehyde. Each method has merits like effectiveness but also drawbacks such as potential toxicity. The various sterilization techniques are applied based on the type of material and whether it is heat-sensitive. Moist heat via autoclaving is commonly used to sterilize medical equipment and pharmaceutical products.
Microorganisms can have both beneficial and harmful effects, so controlling their growth and transmission is important. This document discusses various physical and chemical methods for sterilization, disinfection, sanitization, and antisepsis. Physical methods include heat (moist heat via autoclaving or dry heat), filtration, radiation, and low temperatures. Chemical methods discussed are phenolics, alcohols, halogens (iodine, chlorine), and heavy metals which were historically used but are now less common due to toxicity. The goal is to inactivate pathogens while minimizing harm to humans and materials.
1. The document discusses the production of lactic acid, glutamic acid, and cheese through fermentation processes. Lactic acid bacteria and fungi are used to produce lactic acid from sugars. Corynebacterium glutamicum is commonly used to produce glutamic acid from glucose through biosynthesis pathways.
2. The production of cheese involves pasteurizing milk, adding bacterial cultures, coagulating the milk with rennet enzyme, separating curd from whey, and ripening the curd through the action of molds and bacteria.
3. Specific microorganisms and fermentation steps are outlined for efficiently producing these three compounds at an industrial scale through microbial fermentation of sugars and carbohydrates.
Preservation of industrially important microbial strainAishwarya Konka
This document discusses techniques for preserving industrially important microbial strains. It describes methods where microbes are kept in a continuous metabolic active state through periodic transfer to fresh media, overlaying cultures with mineral oil, and storage in sterile soil. It also covers techniques where microbes are placed in a suspended metabolic state, such as drying in vacuum, lyophilization, cryopreservation in liquid nitrogen, and storage in silica gel. The goal of preservation is to maintain microbial cultures alive, uncontaminated, and as healthy as possible for long periods of time.
The document discusses various methods of food preservation including:
1. Removing or killing microorganisms through methods like asepsis, filtration, washing, and heat treatment.
2. Maintaining conditions unsuitable for microbial growth using techniques such as low temperatures, drying, smoking, and chemical preservatives.
3. Combining preservation methods, for example pasteurizing then refrigerating foods, in order to lengthen the lag phase of microbial growth and prevent spoilage. Proper food preservation prevents foodborne illness and significantly extends the shelf life of foods.
Fermentation is a process that uses microorganisms like yeast or bacteria to convert carbohydrates into organic acids, gases, or alcohol in the absence of oxygen. Fermentation is used in food processing to make foods like cheese and yogurt. Cheese is made through a process of standardizing milk, pasteurization, culturing, coagulation, draining, pressing, aging, and packaging. There are many types of cheese categorized by texture, aging period, production method, milk source, and moisture content such as soft, semi-soft, hard, and processed cheeses. Cheese provides nutritional benefits like vitamins, calcium, and protein but also has risks if consumed in large amounts like increased saturated fat, cholesterol, and potential allerg
This document compares submerged fermentation (SmF) and solid state fermentation (SSF). SmF uses a liquid substrate and is suitable for bacteria that require high moisture, while SSF uses a solid substrate and is better for fungi or bacteria that prefer less moisture. SmF allows for more control of parameters but requires more energy, while SSF is simpler and can use waste materials as substrates. Both methods are used industrially to produce compounds like antibiotics, enzymes, and organic acids.
This document discusses the airlift fermenter. It notes that fermenters must provide a controlled environment for microorganism or cell growth to produce desired products. An airlift fermenter circulates liquid using the density difference between the riser and downcomer columns caused by sparged air or gas. The main type discussed is the concentric draft tube airlift fermenter, which has an internal riser tube that introduces gas to lift liquid up the riser and down the surrounding downcomer tube. Tower loop and ICI deep shaft airlift fermenters are also mentioned. Airlift fermenters provide mixing without mechanical agitation and have high oxygen transfer rates, making them well-suited
This document summarizes batch and continuous sterilization techniques. It discusses that batch sterilization involves injecting steam or direct heating of media to reach 121°C for 20-60 minutes. Continuous sterilization operates at a higher temperature of 140°C for only 30-120 seconds. The document also reviews advantages and disadvantages of each technique, such as batch sterilization being more energy intensive while continuous sterilization risks precipitating certain compounds. Air sterilization methods like filtration and UV radiation are also summarized.
The document discusses the key stages and unit operations involved in downstream processing after fermentation or bioconversion. The main stages are: (1) removal of insolubles through filtration, centrifugation or sedimentation; (2) product isolation using techniques like liquid-liquid extraction, adsorption or ultrafiltration; and (3) product purification using chromatography, crystallization or precipitation. The final stage is (4) product polishing which includes further processing and packaging into a stable form.
The document summarizes the process of beer production. Malt is made from soaked and sprouted grains like barley. Mashing involves mixing malt with water and adjuncts like rice and corn starch. This allows enzymatic degradation of starch to sugars. The liquid produced is wort, which is separated and then fermented with yeast along with hops for flavor. Fermentation yields alcohol and carbon dioxide. The final beer is pasteurized, carbonated, and aged to improve flavor before consumption.
Food Industry of Biotechnology involves preparation of different food items that are used as common part of diet throughout the world.The presentation describes the Industrial preparation of Yogurt.
This document outlines a procedure for isolating microorganisms from a sample using the pour plate method. The aims are to isolate and obtain pure cultures of microorganisms. The principle involves diluting the sample and mixing it with warm agar which is then poured into petri dishes to form individual colonies after incubation. Colonies are then transferred to fresh media for identification. The procedure involves preparing and sterilizing media, diluting the sample, pour plating the dilutions, incubating, and recording results to determine the number of viable microorganisms present.
The document discusses methods for examining food and water microbiologically. There are three main methods discussed: culture media methods, immunoassay methods, and polymerase chain reaction (PCR) methods. Culture media methods involve culturing samples on selective and differential media to isolate and identify microorganisms. Immunoassay methods like ELISA use antigen-antibody binding to detect toxins and microbes. PCR methods amplify and detect targeted nucleic acid sequences to identify pathogens. Examining food and water microbiologically is important to ensure safety and determine processing parameters needed to meet standards.
Sterilization is a process that eliminates all forms of life through physical or chemical means. Media sterilization can be done through boiling, steam exposure, or autoclaving. Air sterilization is commonly done through filtration to provide a continuous supply of sterile air for aerobic fermentation.
Glycerol can be produced by using different processes and feedstocks. For example, it can be obtained by propylene synthesis via several pathways [8], by hydrolysis of oil or by transesterification of fatty acids/oils.
This document discusses various physical methods for food preservation, including ionizing radiation, nonionizing radiation, light, high pressure processing, pulsed electric fields, and modified atmosphere packaging. Ionizing radiation works by affecting nucleic acids and cell membranes, while nonionizing microwave radiation causes protein and nucleic acid denaturation. High pressure processing and pulsed electric fields disrupt cell membranes. Modified atmosphere packaging and vacuum packaging inhibit aerobic microorganisms by reducing oxygen levels.
Downstream processing refers to the stages involved after fermentation or bioconversion, including separation, purification, and packaging of the product. The key stages are removal of insolubles through filtration, centrifugation or flocculation, product isolation using techniques like liquid-liquid extraction or adsorption, product purification using chromatography or crystallization, and product polishing which prepares the product for packaging and storage. Downstream processing aims to recover and purify the target product from the fermentation or reaction broth.
The document discusses various methods for preserving microorganisms. Short term methods include periodic transfer to fresh medium, storage in saline suspension, and refrigeration. Long term methods involve storage under mineral oil, lyophilization (freeze drying), cryopreservation in liquid nitrogen, and storage in sterile soil or silica gel. Lyophilization works by freezing and then reducing moisture content through sublimation and desorption. It allows storage at room temperature for many years but can damage some microbes. Cryopreservation in liquid nitrogen at -196°C also enables long term storage of over 10-30 years without genetic change.
This document summarizes various sterilization methods used in hospitals. It discusses the aims of sterilization and differentiates between sterilization, disinfection, and antisepsis. It then describes various physical sterilization methods like heat, radiation, filtration and chemical methods like alcohols, aldehydes, phenols, and halogens. Specific sterilization techniques are outlined, including autoclaving, dry heat ovens, radiation, and chemical disinfectants. Testing methods for determining the efficacy of sterilization processes are also briefly mentioned.
Sterilization refers to processes that eliminate transmissible agents like bacteria and viruses. There are physical and chemical methods of sterilization. Physical methods include heat sterilization like autoclaving, which is the most widely used method, as well as radiation and filtration. Chemical sterilization uses gases like ethylene oxide and formaldehyde. Each method has merits like effectiveness but also drawbacks such as potential toxicity. The various sterilization techniques are applied based on the type of material and whether it is heat-sensitive. Moist heat via autoclaving is commonly used to sterilize medical equipment and pharmaceutical products.
Sterilization is any process that eliminates transmissible agents like bacteria and viruses. There are physical and chemical methods of sterilization. Physical methods include heat sterilization like autoclaving, which is most widely used, as well as radiation and filtration. Heat sterilization destroys cell constituents but can only be used on thermo-stable products. Radiation sterilization uses gamma rays or electrons on dry products. Filtration removes microbes from liquids and gases. Chemical sterilization uses ethylene oxide or formaldehyde gases, which are mutagenic. Different sterilization methods have various merits and applications in pharmaceuticals and medicine.
1) Rapid detection of bacteria is important for timely analysis in microbial testing. Methods like membrane filtration and direct epifluorescent filter technique allow rapid concentration and enumeration of microbes within 10 minutes.
2) Sterilization methods like heat, radiation, filtration, and gases aim to eliminate bacteria and viruses. Moist heat sterilization through autoclaving at 121°C is very effective. Dry heat sterilization is also used for heat-stable items.
3) Parameters like D-value, z-value, and F-value are used to define the effectiveness of sterilization methods against microbes. Proper validation and monitoring of sterilization processes is important.
Sterilization techniques .TYPES .MERTIES. AND DIMERTIES AND APPLICATION......PALANIANANTH.S
This document discusses sterilization techniques. It defines sterilization as any process that eliminates transmissible agents like bacteria and viruses. The main methods of sterilization discussed are physical (heat, radiation, filtration) and chemical (gaseous). Heat sterilization through moist heat like autoclaving and dry heat is the most widely used method. Radiation uses gamma rays or electrons to sterilize heat-sensitive products. Filtration removes microbes from liquids and gases. Gaseous sterilization uses chemicals like ethylene oxide or formaldehyde that react with microbes. Sterilization is important in medicine to prevent disease transmission and growth and avoid additional surgeries.
This document discusses various sterilization methods including physical (heat, radiation, filtration), chemical (gaseous), and their mechanisms and applications. Heat sterilization is the most widely used method and can be dry heat or moist heat. Radiation uses gamma rays or electrons to damage DNA. Filtration removes microbes physically. Gaseous methods like ethylene oxide act as alkylating agents. Selection depends on material properties and desired sterility level. In-process controls monitor manufacturing to ensure quality. Membrane filtration and direct inoculation are used in sterility testing.
This document provides information about disinfection and sterilization. It defines key terms like disinfection, antisepsis, asepsis, and discusses the difference between antiseptics and disinfectants. It describes various physical agents for sterilization including heat, radiation, and filtration. It also covers different chemical agents used for sterilization like alcohols, chlorine compounds, formaldehyde, glutaraldehyde and hydrogen peroxide. The document provides details on different sterilization techniques and the advantages and disadvantages of various physical and chemical sterilization methods.
This document provides information about disinfection and sterilization. It defines key terms like disinfection, antisepsis, and asepsis. It describes various physical agents for sterilization like heat, radiation, and filtration. It covers types of heat sterilization including moist and dry heat. It also discusses various chemical agents used for sterilization including alcohols, chlorine compounds, formaldehyde, glutaraldehyde and hydrogen peroxide. The document categorizes different types of filters and provides details on filtration sterilization methods.
Sterilization can be achieved through physical or chemical methods. Physical methods include heat (dry heat or moist heat using autoclaves), filtration, and radiation (UV or X-rays). Chemical sterilization involves the use of gases like ethylene oxide or liquids/solutions such as alcohols, phenols, and aldehydes. Common sterilization techniques are dry heat in hot air ovens, moist heat in autoclaves using pressurized steam, ethylene oxide gas, and alcohol or phenol solutions. Each method has advantages and disadvantages depending on the material to be sterilized and effectiveness against different microorganisms.
This document discusses sterilization and disinfection. It defines key terms like sterilization, disinfection, antisepsis. It describes various physical methods of sterilization like heat, radiation, filtration and chemical methods like ethylene oxide and other disinfectants. Heat-based methods include moist heat sterilization using autoclaving and dry heat sterilization using ovens or flaming. Proper monitoring of sterilization methods is important to ensure effectiveness. The ideal characteristics of disinfectants are also discussed.
This document discusses various methods of sterilization that are important in pharmaceutical applications. It describes heat sterilization methods including moist heat using steam and dry heat. Other methods discussed are gaseous sterilization using ethylene oxide or formaldehyde, liquid sterilization using peracetic acid or hydrogen peroxide, radiation sterilization using gamma rays or UV light, and filtration sterilization using membrane filters. Tests for sterility including membrane filtration and direct transfer methods are also summarized along with considerations for evaluating sterilization methods.
The document discusses the history of antiseptic surgery and the development of sterilization techniques. It explains that in the 19th century, surgery had high rates of infection because operating conditions were not aseptic. French scientist Louis Pasteur's work on germ theory influenced Joseph Lister to apply carbolic acid in surgery, reducing infection rates. The document then outlines various physical and chemical methods to control microbial growth through sterilization, disinfection, or inhibiting growth, including heat, radiation, filtration, and chemicals like ethylene oxide. It emphasizes that proper time and temperature application is needed to effectively eliminate microbes.
The document discusses various methods of sterilization including physical agents like heat, radiation and filtration, as well as chemical agents. It defines sterilization as a process that eliminates all microorganisms, while disinfection only destroys pathogenic organisms. Several sterilization techniques are described in detail, such as moist heat methods using steam under pressure in an autoclave, dry heat methods using hot air ovens, and chemical agents like alcohols, aldehydes, and dyes. The ideal properties of chemical disinfectants are also outlined.
This document provides definitions and information about various sterilization methods. It defines sterilization as a process that removes all microorganisms, while disinfection removes pathogenic organisms. The summary then discusses several physical sterilization methods like heat, filtration, radiation and ultrasonic/sonic vibrations. It also covers various chemical sterilization agents like alcohols, aldehydes, dyes, halogens, phenols, surface active agents, metallic salts and gases. For each method or agent, it provides details on their mechanism of action and typical uses.
This document discusses various methods of sterilization and disinfection. It describes sterilization as a process that destroys all microbial life through physical or chemical methods. Disinfection eliminates most pathogens but not bacterial spores. Key sterilization methods discussed include heat (dry and moist), radiation, filtration, and chemicals like ethylene oxide and hydrogen peroxide. Heat is the most common sterilization method. Disinfection can be achieved through chemicals like alcohols, aldehydes, phenols, and halogens; each having different mechanisms of action and advantages/disadvantages.
This document provides information on sterilization methods used in agricultural sciences. It discusses both physical and chemical sterilization techniques. The physical methods covered are dry heat sterilization using hot air ovens, moist heat sterilization using autoclaves, and radiation sterilization using UV light or gamma rays. The chemical methods discussed are sodium hypochlorite, ethanol, mercuric chloride, formaldehyde, and hydrogen peroxide. Autoclaving at 121°C for 30-60 minutes is described as the most common moist heat sterilization technique. Both physical and chemical sterilization methods aim to denature proteins, damage cell membranes, or disrupt DNA/RNA to kill microorganisms.
This document provides information on sterilization methods used in agricultural sciences. It discusses both physical and chemical sterilization techniques. The physical methods covered are dry heat sterilization using hot air ovens, moist heat sterilization using autoclaves, and radiation sterilization using UV light or gamma rays. The chemical methods discussed are sodium hypochlorite, ethanol, mercuric chloride, formaldehyde, and hydrogen peroxide. Autoclaving at 121°C for 30-60 minutes is described as the most common moist heat sterilization technique. Both physical and chemical sterilization methods aim to kill microorganisms through damaging cellular proteins and structures.
The document discusses various methods of sterilization and asepsis. It defines key terms like cleaning, asepsis, antisepsis, disinfection, and sterilization. It describes the Spaulding classification system for categorizing medical instruments based on infection risk. Various sterilization methods are covered in detail, including heat sterilization methods like moist heat using autoclaves and dry heat using hot air ovens. Other methods discussed include filtration, irradiation, ethylene oxide sterilization, and chemical disinfectants. Proper pre-sterilization cleaning and sterility maintenance are also emphasized.
Similar to Aseptic technique, culturing and preservation by Likhith K (20)
Structure and function of immunoglobulins(antibodies) Likhith KLIKHITHK1
Immunoglobulins (Ig) or antibodies are glycoproteins that are produced by plasma cells. B cells are instructed by specific immunogens.For, example, bacterial proteins, to differentiate into plasma cells, which are protein-making cells that participate in humoral immune responses against bacteria, viruses, fungi, parasites, cellular antigens, chemicals, and synthetic substances.
The immunogen or antigen reacts with a B-cell receptor (BCR) on the cell surface of B lymphocytes, and a signal is produced that directs the activation of transcription factors to stimulate the synthesis of antibodies, which are highly specific for the immunogen that stimulated the B cell. Furthermore, one clone of B cell makes an immunoglobulin (specificity). Besides, the immune system remembers the antigens that caused a previous reaction (memory) due to the development of memory B cells. These are intermediate, differentiated B cells with the capability to quickly become plasma cells. Circulating antibodies recognize antigen in tissue fluids and serum. This activity describes the physiology and pathophysiology of immunoglobulins
Quantitative estimation of carbohydrates Likhith KLIKHITHK1
Carbohydrates are one of the three macronutrients in the human diet, along with protein and fat. These molecules contain carbon, hydrogen, and oxygen atoms. Carbohydrates play an important role in the human body. They act as an energy source, help control blood glucose and insulin metabolism, participate in cholesterol and triglyceride metabolism, and help with fermentation. The digestive tract begins to break down carbohydrates into glucose, which is used for energy, upon consumption. Any extra glucose in the bloodstream is stored in the liver and muscle tissue until further energy is needed. Carbohydrates is an umbrella term that encompasses sugar, fruits, vegetables, fibers, and legumes. While there are numerous divisions of carbohydrates, the human diet benefits mostly from a certain subset.
The advent of the polymerase chain reaction (PCR) radically transformed biological science from the time it was first discovered (Mullis, 1990). For the first time, it allowed for specific detection and production of large amounts of DNA. PCR-based strategies have propelled huge scientific endeavors such as the Human Genome Project. The technique is currently widely used by clinicians and researchers to diagnose diseases, clone and sequence genes, and carry out sophisticated quantitative and genomic studies in a rapid and very sensitive manner. One of the most important medical applications of the classical PCR method is the detection of pathogens. In addition, the PCR assay is used in forensic medicine to identify criminals. Because of its widespread use, it is important to understand the basic principles of PCR and how its use can be modified to provide for sophisticated analysis of genes and the genome
Recently, the advantages of biopolymers over conventional plastic polymers are unprecedented, provided that they are used in situations in which they raise the functionality and generate extra benefits for human life. Therefore, biopolymers have received much attention because they play an important place in day-to-day life for their specific tunable characteristics, making them attractive in a wide range of applications. Biopolymers can produce materials with tunable properties such as biodegradability, biocompatibility, renewability, inexpensiveness, availability, which are critically important for designing materials for use in biomedical applications. In addition to these properties, smart biopolymers could be prepared by changing the polymer components, which would create more target oriented applications. Biopolymers are potentially used in biomedical applications, including drug delivery, infections, tissue engineering, wound healings, and other as wells.
Quantitative estimation of protein Likhith KLIKHITHK1
This document provides information about quantitatively estimating the amount of proteins in a sample. It discusses several common methods for protein quantification, including the Lowry method, Bradford method, Biuret method, and Bicinchoninic Acid (BCA) method. For the Lowry and Bradford methods, it provides details on the principles, reagents used, and procedures for making standard curves and estimating protein concentration in an unknown sample. The document emphasizes that accurate protein quantification is important for protein studies in research.
Transparent unstained samples do not absorb light and are called phase objects. When light passes through a sample area with no phase object, there is no significant change in the refractive index or optical path length. Non-diffracted light is referred to as direct or zero-order light as it continues unchanged through the sample. On the other hand, when the light passes through an area of the sample with a phase object, small changes in the refractive index will diffract and scatter some light and cause changes to the optical path length, depending on the thickness and refractive index of each structure. Thicker the structure, the greater the diffraction of the light. The diffracted light represents only a small part of the total light that has passed through the sample. This diffracted light arrives at the detector out of phase with the direct light. The small phase shift created by this, is not enough to cause great interference between the direct and diffracted light. Which along with the low absorption of transparent structures means there is negligible amplitude difference between areas where such structures are present and where they are not. Phase-contrast microscopy is a method that manipulates this property of phase objects to introduce additional interference between the direct and diffracted light. This method transforms differences in phase into differences in brightness, increasing contrast in images of non-absorbing samples.
In light microscopy, illuminating light is passed through the sample as uniformly as possible over the field of view. For thicker samples, where the objective lens does not have sufficient depth of focus, light from sample planes above and below the focal plane will also be detected. The out of focus light will add blur to the image reducing the resolution. In fluorescence microscopy, any dye molecules in the field of view will be stimulated, including those in out-of-focus planes. Confocal microscopy provides a means of rejecting the out-of-focus light from the detector such that it does not contribute blur to the images being collected. This technique allows for high-resolution imaging in thick tissues.
In a confocal microscope, the illumination and detection optics are focused on the same diffraction limited spot in the sample, which is the only spot imaged by the detector during a confocal scan. To generate a complete image, the spot must be moved over the sample and data collected point by point.
A significant advantage of the confocal microscope is the optical sectioning provided, which allows for 3D reconstruction of a sample from high-resolution stacks of images. The primary functions of a confocal microscope are to produce a point source of light and reject out-of-focus light, which provides the ability to image deep into tissues with high resolution, and optical sectioning for 3D reconstructions of imaged samples. The basic principle include illumination and detection optics are focused on the same diffraction-limited spot, which is moved over the sample to build the complete image on the detector. The entire field of view is illuminated during confocal imaging, anything outside the focal plane contributes little to the image, lessening the haze observed in standard light microscopy with thick and highly-scattering samples, and providing optical sectioning.
Atomic force microscopy (AFM) is a scanning probe technique capable of imaging surfaces at high resolution. AFM uses a sharp tip that feels the sample surface to detect sub-nanometer level changes. AFM can image samples in liquid and requires minimal sample preparation. The document discusses various combinations of AFM with other techniques like infrared spectroscopy, optical microscopy, and fluorescence microscopy. It also covers the basic principles, working, scanning modes, applications and advantages of AFM for imaging polymers and other materials.
Fluorescence as a phenomenon is part of a larger family of related luminescent processes in which a susceptible substance absorbs light, only to reemit light (photons) from electronically excited states after a given time.
Photo luminescent processes that are generated through excitation, whether this is via physical, mechanical, or chemical mechanisms, can generally be subdivided into fluorescence and phosphorescence. Absorption of a light quantum (blue) causes an electron to move to a higher energy orbit. After residing in this “excited state” for a particular time, the fluorescence lifetime, the electron falls back to its original orbit and the fluorochrome dissipates the excess energy by emitting a photon (green).
Compounds that display fluorescent properties are generally termed fluorescent probes or dyes. Often ‘fluorochrome’ and ‘fluorophore’ are used interchangeably. The term ‘fluorophore’ refers to fluorochromes that are conjugated covalently or through adsorption to biological macromolecules, such as nucleic acids, lipids, or proteins. Fluorochromes come in different flavors and include organic molecules (dyes), inorganic ions (e.g., lanthanide ions such as Eu, Tb, Yb, etc.)fluorescent proteins (e.g., green fluorescent protein) atoms (such as gaseous mercury in glass light tubes).
Recently, inorganic luminescent semiconducting nanoparticles, quantum dots, have been introduced as labels for biological assays, bio-imaging applications, and theragnostic purposes (the combination of diagnostic and therapeutic modalities in one and the same particle).
Fluorescence microscopy provides an efficient and unique approach to study fixed and living cells because of its versatility, specificity, and high sensitivity.
Fluorescence microscopes can both detect the fluorescence emitted from labeled molecules in biological samples as images or photometric data from which intensities and emission spectra can be deduced. By exploiting the characteristics of fluorescence, various techniques have been developed that enable the visualization and analysis of complex dynamic events in cells, organelles, and sub-organelle components within the biological specimen.
The most common techniques are
Fluorescence recovery after photo bleaching (FRAP)
Fluorescence loss in photo bleaching (FLIP)
Fluorescence localization after photo bleaching (FLAP)
Fluorescence resonance energy transfer (FRET)
Transmission electron microscope (TEM) Likhith KLIKHITHK1
Microscopy is a means by which an object is transformed in to magnified image. There are different ways for magnifying the images of very small objects by large amounts. In any type of microscopy (optical microscopy or electron microscopy), a wave of wavelength λ (light wave or electron wave) interacts with the matter and as a result of this interaction we get the
microstructural information about the object. As the study of the materials at the nano-metric level is drawing much attention of the researchers in the current era, Electron Microscopy becomes a very important physical characterization tool at the nano-metric level. Electron Microscopy stands far ahead of the optical microscopy as it can provide the much improved
resolution and depth of focus compared to optical microscopy. This is a very introductory report on the basics of the electron microscopy (particularly on Transmission electron microscopy). Transmission electron Microscopy (TEM) operates on the same basic principles as the light microscope but uses electrons as “light source” and their much lower wavelength makes it possible to get a resolution thousand times better than with a light Microscopy.
Scanning electron microscopy (SEM) Likhith KLIKHITHK1
Scanning electron microscopy (SEM) is a technique that uses electron beams to produce high-resolution images of samples. SEM has higher magnification and resolution than optical microscopy. The document discusses the history, components, working principles and applications of SEM. It provides details on different SEM types including conventional SEM, environmental SEM and low vacuum SEM and factors to consider when purchasing an SEM instrument. SEM is widely used in various fields to image morphology, examine composition and crystal structure at micro and nano scales.
Crystallography and X-ray diffraction (XRD) Likhith KLIKHITHK1
Atoms in materials are arranged into crystal structures and microstructures.
Periodic arrangement of atoms depends strongly on external factors such as temperature, pressure, and cooling rate during solidification. Solid elements and their compounds are classified into amorphous, polycrystalline, and single crystalline materials. The amorphous solid materials are isotropic in nature because their atomic arrangements are not regular and possess the same properties in all directions. In contrast, the crystalline materials are anisotropic because their atoms are arranged in regular and repeated pattern, and their properties vary with direction. The polycrystalline materials are combinations of several crystals of varying shapes and sizes. The properties of polycrystalline materials are strongly dependent on distribution of crystals sizes, shapes, and orientations within the individual crystal. Diffraction pattern or intensities of X-ray diffraction techniques are used for characterizing and probing arrangement of atoms in each unit cell, position of atoms, and atomic spacing angles because of comparative wavelength of X-ray to atomic size.The X-ray diffraction, which is a non-destructive technique, has wide range of material analysis including minerals, metals, polymers, ceramics, plastics, semiconductors, and solar cells. The technique also has wide industry application including aerospace, power generation, microelectronics, and several others. The X-ray crystallography remained a complex field of study despite wide industrial applications.
This document provides an overview of Fourier transform infrared (FTIR) spectroscopy. It discusses the electromagnetic spectrum and how infrared radiation interacts with molecular bonds to produce vibrational modes. The basic principles of FTIR are explained, including how an interferogram is produced and transformed into an infrared absorption spectrum using Fourier transform. Common instrumentation components like detectors, radiation sources, and sample holders are also mentioned. The document serves as an introduction to FTIR spectroscopy and the molecular information it can provide through analysis of infrared absorption spectra.
UV-visible spectroscopy is a fast analytical technique that measures the absorbance or transmittance of light. Although the UV wavelength ranges from 100–380 nm and the visible component goes up to 800 nm, most of the spectrophotometers have a working wavelength range between 200–1100 nm.
The practical range for UV-vis spectroscopy varies from 200–800 nm; above 800 nm is infrared, while below 200 nm is known as vacuum UV. The ability of matter to absorb and to emit light is what defines its color and the human eye is capable of differentiating up to 10 million unique colors. Light passes through media (transmission), reflects off both opaque and transparent surfaces, and is refracted by crystals. Covalently unsaturated compounds with electronic transition energy differences equivalent to the energy of the UV-visible light absorb at specific wavelengths. These compounds are known as chromophores and are responsible for their color. Covalently saturated groups that do not absorb UV-visible electromagnetic radiation but affect the absorption of chromophore groups are called auxochromes. When UV-vis radiation hits chromophores, electrons in the ground state jump to an excited state, which we refer to as electron-excitation, while auxochromes are electron-donating and have the capacity to affect the color of choromophores while they do not change color themselves. Water and alcohols are mostly transparent and do not absorb in the UV-vis range and so are excellent mediums for UV-visible spectroscopy. Acetone and dimethylformamide (DMF) are good solvents for compounds insoluble in water and alcohol, but they absorb light below 320 and 275 nm, respectively, so are appropriate only above these cut-off wavelengths.
Enzymes principles and applications Likhith KLIKHITHK1
Enzymes are biological catalysts (also known as biocatalysts) that speed up biochemical reactions in living organisms. They can also be extracted from cells and then used to catalyse a wide range of commercially important processes. For example, they have important roles in the production of sweetening agents and the modification of antibiotics, they are used in washing powders and various cleaning products, and they play a key role in analytical devices and assays that have clinical, forensic and environmental applications. The word ‘enzyme’ was first used by the German physiologist Wilhelm Kühne in 1878, when he was describing the ability of yeast to produce alcohol from sugars, and it is derived from the Greek words en (meaning ‘within’) and zume (meaning ‘yeast’).In the late nineteenth century and early twentieth century, significant advances were made in the extraction, characterization and commercial exploitation of many enzymes, but it was not until the 1920s that enzymes were crystallized, revealing that catalytic activity is associated with protein molecules. For the next 60 years or so it was believed that all enzymes were proteins, but in the 1980s it was found that some ribonucleic acid (RNA) molecules are also able to exert catalytic effects.These RNAs, which are called ribozymes, play an important role in gene expression. In the same decade, biochemists also developed the technology to generate antibodies that possess catalytic properties. These so-called ‘abzymes’ have significant potential both as novel industrial catalysts and in therapeutics. Notwithstanding these notable exceptions, much of classical enzymology, and the remainder of this essay, is focused on the proteins that possess catalytic activity.As catalysts, enzymes are only required in very low concentrations, and they speed up reactions without themselves being consumed during the reaction.
Cheese is a very popular food produced worldwide from the milk of ruminants using a combination of physical treatments. Key milk components for the transformation of milk into curd are casein and calcium. The majority of cheese varieties are based on the curd of modified casein micelles that result from the enzymatic rennet clotting of milk in the presence of calcium ions. The remarkable ability of the spontaneous syneresis of rennet-induced curds can be adjusted to the desired level by biological acidification, cutting, stirring, heating, pressing and salting in order to achieve the desired level of water removal in the form of whey. The mode of curdling (acid or rennet coagulation), the conditions, and the combinations of curd treatments result in numerous cheese varieties with different appearances, textures, flavors and shelf lives. Moreover, most of them are kept under specific temperature and humidity conditions to ripen for a short or a considerable amount of time. The classification of cheese varieties is not unambiguous and can be based on various criteria. For example, cheeses can be classified according to their moisture content related to yield and shelf life or according to specific features related to the treatments applied during cheesemaking and ripening. During ripening, the main solid constituents of young cheese—fat and caseins—undergo changes that increase the concentration of small size compounds in cheese—such as peptides, amino acids, small volatile molecules—control moisture loss and configure textural properties. In particular, the compounds of mature cheese flavor result from complicated biochemical pathways that take place during cheese ripening or even storage.
The function of the fermenter or bioreactor is to provide a suitable environment in which an organism can efficiently produce a target product—the target product might be cell biomass,metabolite and bioconversion Product. It must be so designed that it is able to provide the optimum environments or conditions that will allow supporting the growth of the microorganisms. The design and mode of operation of a fermenter mainly depends on the production organism, the optimal operating condition required for target product formation, product value and scale of production.
The choice of microorganisms is diverse to be used in the fermentation studies. Bacteria, Unicellular fungi, Virus, Algal cells have all been cultivated in fermenters. Now more and more attempts are tried to cultivate single plant and animal cells in fermenters. It is very important for us to know the physical and physiological characteristics of the type of cells which we use in the fermentation. Before designing the vessel, the fermentation vessel must fulfill certain requirements that is needed that will ensure the fermentation process will occur efficiently. Some of the actuated parameters are: the agitation speed, the aeration rate, the heating intensity or cooling rate, and the nutrients feeding rate, acid or base valve. Precise environmental control is of considerable interest in fermentations since oscillations may lower the system efficiency, increase the plasmid instability and produce undesirable end products.
Penicillin is one of the most commonly used antibiotics globally, as it has a wide range of clinical indications. Penicillin is effective against many different types of infections involving gram-positive cocci, gram-positive rods (e.g., Listeria), most anaerobes, and gram-negative cocci (e.g., Neisseria). Importantly, certain bacterial species have obtained penicillin resistance, including enterococci. Enterococci infections now receive treatment with a combination of penicillin and streptomycin or gentamicin. Certain gram-negative rods are also resistant to penicillin due to penicillin’s poor ability to penetrate the porin channel. However, later generations of broad-spectrum penicillins are effective against gram-negative rods. Second-generation penicillins (ampicillin and amoxicillin) can also penetrate the porin channel, making these drugs effective against Proteus mirabilis, Shigella, H. influenzae, Salmonella, and E. coli. Third-generation penicillins such as carbenicillin and ticarcillin are also able to penetrate gram-negative bacterial porin channels. Fourth-generation penicillins such as piperacillin are effective against the same bacterial strains as third-generation penicillins as well as Klebsiella, enterococci, Pseudomonas aeruginosa, and Bacteroides fragilis.
Beer is one of the oldest and most widely consumed alcoholic drinks in the world, and the third most popular drink overall after water and tea. Beer is brewed from cereal grains most commonly from malted barley, though wheat, maize (corn), and rice are also used. The process of beer production is known as brewing. Word brewing is derived from “Bieber” its means to drink.
Brewing is a complex fermentation process. It differs from other industrial fermentation because flavor, aroma, clarity, color, foam production, foam stability and percentage of alcohol are the factors associated with finished product.
During the brewing process, fermentation of the starch sugars in the wort produces ethanol and carbonation in the resulting beer. Most modern beer is brewed with hops, which add bitterness and other flavors and act as a natural preservative and stabilizing agent. Other flavoring agents such as gruit, herbs, or fruits may be included or used instead of hops.
Chromatography is based on the principle where molecules in mixture applied onto the surface or into the solid, and fluid stationary phase (stable phase) is separating from each other while moving with the aid of a mobile phase.
The factors effective on this separation process include molecular characteristics related to adsorption (liquid-solid), partition (liquid-solid), and affinity or differences among their molecular weights
Because of these differences, some components of the mixture stay longer in the stationary phase, and they move slowly in the chromatography system, while others pass rapidly into mobile phase, and leave the system faster.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
ANAMOLOUS SECONDARY GROWTH IN DICOT ROOTS.pptxRASHMI M G
Abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Current Ms word generated power point presentation covers major details about the micronuclei test. It's significance and assays to conduct it. It is used to detect the micronuclei formation inside the cells of nearly every multicellular organism. It's formation takes place during chromosomal sepration at metaphase.
Aseptic technique, culturing and preservation by Likhith K
1. Aseptic Methods of Inoculation,
Achievements and Maintenance
BY
LIKHITH K
BiSEP – 2021
Dept of Biotechnology
St Aloysius College
Mangaluru, Karnataka
2. What is aseptic technique ?
Objective
How can microorganism be killed?
Concepts in maintaining sterile conditions
Instrument used in sterilization
Flaming of inoculation loop
Chemical sterilization
Preview to maintenance
Common methods of isolation
Preservation
Methods of preservation
Conclusion
Reference
Contents
3. What is Aseptic Technique?
Aseptic technique is a method of compete elimination
of microorganism, used in laboratories or clinical
setting to prevent the contamination or growth of
unwanted microorganism.
4. Objectives
The goal is to prevent contamination of what you are
working on, whether it is someone’s wound or a
bacterial culture that is of interest.
Microorganisms are everywhere! In the environment
and in and on your body, Therefore, aseptic technique
takes vigilance as bacteria and other microbes may be
present on your work bench, floating in the air currents,
etc.
Proper aseptic technique can prevent contamination
from any source.
5. How can microorganisms be killed?
Principle of sterilization :
Denaturation of proteins
Interruption of DNA synthesis/repair
Disruption of cell membranes
6. How can we Minimize contamination
One way to minimize contamination is to not perform
your techniques in drafty areas, this lessens the chance
of air-born microorganisms contaminating your culture.
Also you should always make sure that the surface that
you are working on has been disinfected, eliminating
another potential source of contamination.
Any materials that will contact your experiments should
be sterilized by autoclaving and flaming.
7. Concepts in maintaining sterile conditions
Sterilization : It is a process by which an article,
surface or medium is made free of all microorganisms
either in vegetative or spore form.
Disinfection : Destruction of all pathogens or
organisms capable of producing infections but not
necessarily spores. All organisms may not be killed but
the number is reduced to a level that is no longer
harmful to health.
8. Antiseptics : Chemical disinfectants which can safely
be applied to living tissues and are used to prevent
infection by inhibiting the growth of microorganisms.
Asepsis : Technique by which the occurrence of
infection into an uninfected tissue is prevented.
9.
10. Instruments used in sterilization
Physical Method of Sterilization
Principle Instruments used
1 Dry Heat Hot Air Oven
2 Moist Heat Autoclave
3 Radiation Gamma-ray Chamber
11. Hot air oven
Sterilization by dry heat is performed by conduction. The
temperature is consumed by the surface of the objects, then
moves towards the core of the object, coating by coating.
The whole object will ultimately attain the temperature
needed for sterilization to take place(150 to 180C).
Dry heat causes most of the injury by oxidizing particles.
The primary cell components are damaged and the organism
dies. The temperature is kept for about an hour to eliminate
the most ambitious of the resistant spores.
13. Autoclave
The basic principle of steam sterilization, as accomplished in
an autoclave, is to expose each item to direct steam contact at
the required temperature and pressure for the specified time.
Thus, there are four parameters of steam sterilization: steam,
pressure, temperature, and time. The ideal steam for
sterilization is dry saturated steam and entrained water
(dryness fraction ≥97%).
Pressure serves as a means to obtain the high temperatures
necessary to quickly kill microorganisms. Specific
temperatures must be obtained to ensure the microbicidal
activity. The two common steam-sterilizing temperatures are
121°C (250°F) and 132°C (270°F).
14. These temperatures (and other high temperatures)must be
maintained for a minimal time to kill microorganisms.
Recognized minimum exposure periods for sterilization of
wrapped healthcare supplies are 30 minutes at 121°C (250°F) in
a gravity displacement sterilizer or 4 minutes at 132°C (270°F)
in a pre vacuum sterilizer.
At constant temperatures, sterilization times vary depending on
the type of item (e.g., metal versus rubber, plastic, items with
lumens), whether the item is wrapped or unwrapped, and the
sterilizer type.
Moist heat destroys microorganisms by the irreversible
coagulation and denaturation of enzymes and structural proteins.
In support of this fact, it has been found that the presence of
moisture significantly affects the coagulation temperature of
proteins and the temperature at which microorganisms are
destroyed.
16. Gamma ray chamber
The gamma irradiation process uses Cobalt 60 radiation to kill
microorganisms on a variety of different products in a specially
designed cell.
Gamma radiation is generated by the decay of the radioisotope
Cobalt 60, with the resultant high energy photons being an
effective sterilant.
A key characteristic of gamma irradiation is the high penetration
capability, which allows for delivery of target radiation dose to
areas of products that may be higher in density.
The unit of absorbed dose is kiloGray, expressed as kGy. Delivery
and absorption of dose by product is determined by product
density, packaging size, dose rate, exposure time and facility
design.
18. The Laminar Flow Unit
A laminar flow unit (or hood) is a sophisticated appliance that can
further help prevent contamination of reagents and biological
cultures. Used correctly, it provides the work space with clean, ultra
filtered air.
It also keeps room air from entering the work area and
both suspends and removes airborne contaminants introduced into
the work area by personnel.
The most important part of a laminar flow hood is a high-efficiency
bacteria-retentive filter, i.e., the HEPA (high-efficiency particulate
air) filter.
19. A certified HEPA filter must capture a minimum of 99.97% of
dust, pollen, mold, bacteria, and any airborne particles with a size
of >0.3 μm at 85 liters/min.
Laminar flow hoods are essential components of many bio safety
level (BSL)-2 laboratories, where they help prevent spread of
viruses and some bacteria.
24. Chemical sterilization
Gaseous Sterilization
Gaseous sterilization involves the process of exposing
equipment or devices to different gases in a closed heated or
pressurized chamber.
Gaseous sterilization is a more effective technique as gases
can pass through a tiny orifice and provide more effective
results.
Besides, gases are commonly used along with heat treatment
which also facilitates the functioning of the gases.
However, there is an issue of release of some toxic gases
during the process which needs to be removed regularly from
the system.
25. The mechanism of action is different for different types of gases.
Some of the common gases used for gaseous sterilization are
explained below:
a)Ethylene oxide
Ethylene oxide (EO) gas is a common gas used for chemical
treatment applied to sterilize, pasteurize, or disinfect different
types of equipment and surfaces because of its wide range of
compatibility with different materials.
EO treatment often replaces other sterilization techniques like
heat, radiation, and even chemicals in cases where the objects are
sensitive to these techniques.
The mechanism of antimicrobial action of this gas is assumed to
be through the alkylation of sulphydryl, amino, hydroxyl, and
carboxyl groups on proteins and imino groups of nucleic acids.
26. b) Formaldehyde
Formaldehyde is another important highly reactive gas which is
used for sterilization.
This gas is obtained by heating formalin (37%w/v) to a
temperature of 70-80°C.
It possesses broad-spectrum biocidal activity and has found
application in the sterilization of reusable surgical instruments,
specific medical, diagnostic and electrical equipment, and the
surface sterilization of powders.
Formaldehyde doesn’t have the same penetrating power of
ethylene oxide but works on the same principle of modification
of protein and nucleic acid.
Formaldehyde can generally be detected by smell at
concentrations lower than those permitted in the atmosphere and
thus can be detected during leakage or other such accidents.
27. c) Nitrogen dioxide (NO2)
Nitrogen dioxide is a rapid and effective sterilant that can
be used for the removal of common bacteria, fungi, and
even spores.
NO2 has a low boiling point (20°C) which allows a high
vapor pressure at standard temperature.
This property of NO2 enables the use of the gas at standard
temperature and pressure.
The biocidal action of this gas involves the degradation of
DNA by the nitration of phosphate backbone, which results
in lethal effects on the exposed organism as it absorbs NO2.
An advantage of this gas is that no condensation of the gas
occurs on the surface of the devices because of the low
level of gas used and the high vapor pressure. This avoids
the need for direct aeration after the process of sterilization.
28. d) Ozone
Ozone is a highly reactive industrial gas that is commonly used
to sterilize air and water and as a disinfectant for surfaces.
Ozone is a potent oxidizing property that is capable of destroying
a wide range of organisms including prions, without the use of
hazardous chemicals as ozone is usually generated from medical-
grade oxygen.
Similarly, the high reactivity of ozone allows the removal of
waste ozone by converting the ozone into oxygen by passing it
through a simple catalyst.
However, because ozone is an unstable and reactive gas, it has to
be produced on-site, which limits the use of ozone in different
settings.
It is also very hazardous and thus only be used at a concentration
of 5ppm, which is 160 times less than that of ethylene oxide.
29. Liquid Sterilization
Liquid sterilization is the process of sterilization which involves
the submerging of equipment in the liquid sterilant to kill all
viable microorganisms and their spores.
Although liquid sterilization is not as effective as gaseous
sterilization, it is appropriate in conditions where a low level of
contamination is present.
Different liquid chemicals used for liquid sterilization includes the
following:
a) Hydrogen peroxide
Hydrogen peroxide is a liquid chemical sterilizing agent which is
a strong oxidant and can destroy a wide range of microorganisms.
It is useful in the sterilization of heat or temperature-sensitive
equipment like endoscopes. In medical applications, a higher
concentration (35-90%) is used.
H2O2 has a short sterilization cycle time as these cycles are as
short as 28 minutes where ethylene oxide has cycles that as long
as 10-12 hours.
30. b) Glutaraldehyde
Glutaraldehyde is an accepted liquid sterilizing agent which
requires comparatively long immersion time. For the removal of
all spores, it requires as long as 22 hours of immersion time.
The presence of solid particles further increases the immersion
time.
The penetration power is also meagre as it takes hours to penetrate
a block of tissues.
The use of glutaraldehyde is thus limited to certain surfaces with
less contamination.
c) Hypochlorite
Hypochlorite solution, which is also called liquid bleach, is
another liquid chemical that can be used as a disinfectant, even
though sterilization is difficult to obtain with this chemical.
Submerging devices for a short period in liquid bleach might kill
some pathogenic organisms but to reach sterilization submersion
for 20-24 hours is required.
31. It is an oxidizing agent and thus acts by oxidizing organic
compounds which results in the modification of proteins in
microbes which might ultimately lead to death.
Appropriate concentrations of hypochlorite can be used for the
disinfection of workstations and even surfaces to clean blood spills
and other liquids.
32. Preview to maintenance
Microorganisms are generally found in nature (air, soil and
water) as mixed populations.
Even the diseased parts of plants and animals contain a great
number of microorganisms, which differ markedly from the
microorganisms of other environments.
To study the specific role played by a specific microorganism in
its environment, one must isolate the same in pure culture.
33. The two major steps of obtaining a pure culture are as follows :
Firstly, the culture has to be diluted until the various individual
microorganisms are separated far apart on agar surface that after
incubation they form visible colonies isolated from the colonies
of other microorganisms.
Secondly, an isolated colony has to be aseptically picked off the
isolation plate
36. There are several methods of isolating the pure culture of bacteria,
like, streak plate method, pour plate method, spread plate method
and serial dilution.
Why is pure cultures important ?
Pure cultures are important in microbiology for the following
reasons
Once purified, the isolated species can then be cultivated with the
knowledge that only the desired microorganism is being grown.
A pure culture can be correctly identified for accurate studying and
testing and diagnosis in a clinical environment.
Testing/experimenting with a pure culture ensures that the same
results can be achieved regardless of how many time the test is
repeated.
Pure culture spontaneous mutation rate is low
Pure culture clone is 99.999% identical
37. Common methods of isolation
The process of screening a pure culture by separating one type of
microbes from a mixture is called Isolation.
Some common isolation methods are;
I) Streak plate method
II) Pour plate method-
a) a)Loop dilution technique
b) b) Serial Dilution technique
III) Spread plate method
IV) Micromanipulator method
V) Roll tube method
39. Preservation
To maintain pure culture for extended periods in a viable
conditions, without any genetic change is referred as Preservation.
The aim of preservation is to stop the cell division at a particular
stage i.e. to stop microbial growth or at least lower the growth rate.
Due to this toxic chemicals are not accumulated and hence
viability of microorganisms is not affected.
40. Objectives
To maintain isolated pure cultures for extended periods in a
viable conditions.
To avoid the contamination.
To restrict genetic change (Mutation)
41. The method of preservation is mainly of two
types-
1. Short term methods
2. Long term methods
42. Short term methods
Periodic transfer to fresh media-
Culture can be maintained by periodically preparing a fresh
culture from the previous stock culture.
Many of the more common microbes remain viable for several
weeks or months on a medium like Nutrient agar.
It is an advantageous as it is a simple method and any special
apparatus are not required. However it is easy to recover the
culture.
The transfer has the disadvantage of failing to prevent changes in
the characteristics of a strain due to development of variants and
mutants and risk of contamination is also more in this process.
43. Preservation of bacteria using glycerol
Bacteria can be frozen using 15% glycerol.
The glycerol is diluted to 30% and an equal amount of glycerol
and culture broth are mixed, dispensed into tubes, and then
frozen at -10˚ C.
The viability of organisms varied such as Escherichia coli,
Diplococcus pneumonia etc. viable for 5 months, Haemophilus
influnzae viable for 4 months, Neisseria meningtidis for 6 weeks
and Neisseria gonorrhoeae for 3 weeks
44. Storage by drying method
Spores of some microbes which are sensitive to freeze- drying, can
be preserved by drying from the liquid state rather than the frozen
state.
Different procedures of drying methods are as follows:
Paper disc: A thick suspension of bacteria is placed on sterile discs
of thick absorbent paper, which are then dried over phosphorus
pentoxide in a desiccation under vacuum.
Gelatin disc: Drops of bacterial suspension in gelatin are placed on
sterile plastic petriplates and then dried off over P2O5 under
vacuum.
45. L-drying: Bacteria in small ampoules are dried from the liquid
state using a vacuum pump and desiccant and a water bath to
control the temperature.
In this suspension of the organisms are dried under vacuum
from the liquid state without freezing taking place.
Apart from the mentioned methods the organisms are also dried
over Calcium Chloride in vacuum and are stored in the
refrigerator.
At such conditions the organisms survive for longer period than
the air dried cultures.
46. Storage by refrigeration
Culture medium can be successfully stored in refrigerators or cold
rooms, when the temperature is maintained at 4˚C.
At this temperature range the metabolic activities of microbes
slows down greatly and only small quantity of nutrients will be
utilized.
This method cannot be used for a very long time because toxic
products get accumulated which can kill the microbes.
47. Long term methods
Mineral oil or liquid paraffin storage
In this method sterile liquid paraffin is poured over the slant
culture of microbes and stored upright at room temperature.
Where as cultures can also be maintained by covering agar slants
by sterile mineral oil which is stored at room temperature or
preferably at 0-5°C.
48. It limit the oxygen access that reduces the microorganism’s
metabolism and growth, as well as to cell drying during
preservation.
The preservation period for bacteria from the genera Azotobacter
and Mycobacterium is from 7-10 years, for Bacillus it is 8-12
years.
Storage in saline suspension:
Bacterial culture is preserved in 1% salt concentration in screw
caped tubes to prevent evaporation.
The tubes are stored in room temperature.
Whenever needed the transfer is made on Agar Slant.
49. Immersion in distilled water:
Another inexpensive and low-maintenance method for storing
fungal culture is to immerse them in distilled water.
Fungi can be stored in this method at 20˚C, survived up to 2-10
years depending upon the species.
50. Storage in sterile soil
It is mainly applied for the preservation of sporulating
microorganisms. Fusarium, Penicillium, Alternaria, Rhizopus etc.
proved successful for store in sterile soil.
Soil storage involves inoculation of 1ml of spore suspension into
soil (autoclaved twice) and incubating at room temperature for 5-
10 days.
The initial growth period allows the fungus to use the available
moisture and gradually to become dormant.
The bottles are then stored at refrigerator.
Viability of organisms found around 70-80 years.
51. Lyophilization (Freeze–drying)
It is a vacuum sublimation technique.
Freeze drying products are hygroscopic and must be protected
from moisture during storage.
By freezing the cells in a medium that contain a lyo protectant
(usually sucrose) and then pulling the water out using
vacuum(sublimation), cells can be effectively preserved.
Freezing must be very rapid, with the temperature lowered to
well below 0˚C (as such -20˚C).
Lyophilized cultures are stored in the dark 4˚C in refrigerators.
Many microbes preserved by this method have remained viable
and unchanged in their characteristic more than 20 years.
52. It is very advantageous as only minimal storage space is required
to preserve.
53. Cryopreservation
Cryopreservation (i.e. freezing in liquid nitrogen at -196˚C or in
the gas phase above the liquid nitrogen at -150˚C) helps survival
of pure cultures for long storage time.
In this method, the microorganisms of culture are rapidly frozen
in liquid nitrogen at -196˚C in the presence of stabilizing agents
such as Glycerol or Dimethyl Sulfoxide (DMSO) that prevent the
cell damage due to formation of ice crystals and promote cell
survival.
54. By this method species can remain viable for 10-30 years without
undergoing change in their characteristics.
55. Stored in silica gel
Microbes can be stored in silica gel powder at low temperature
for a period 1- 2 years.
The basic principle in this technique is quick desiccation at low
temperature, which allows the cell to remain viable for a long
period of time.
Some of the species which are preserved on anhydrous silica gel
are such as Saccharomyces cerevisiae, Aspergillus nidulans,
Pseudomonas denitrificans, Escherichia coli etc.
56. Conclusion
Many of the microorganisms we will be working with in lab are
known pathogens.
Proper and appropriate aseptic technique is vitally important for
the safety of all lab personnel; it is also essential for the
successful completion of the lab portion and experiments.
The skills and awareness you develop practicing aseptic
technique will carry over to your career as a health professional.
Whichever technique is used for preservation and maintenance
of industrially important organisms it is essential to check the
quality of the preserved organisms stocks.
57. Each batch of newly preserved cultures should be routinely
checked to ensure their quality. However preservation is essential
as it reveals great importance in the field of science.
Preservation helps in research purposes, industry as well as in
biotechnological field.