A pure culture theoretically contains a single bacterial species. There are a number of procedures available for the isolation of pure cultures from mixed populations. A pure culture may be isolated by the use of special media with specific chemical or physical agents that allow the enrichment or selection of one
organism over another.
Preservation of industrially important microorganisms, methods of preservation, periodic transfer, storage in saline suspension, storage in sterile soil, cryopreservation
Preservation of industrially important microorganisms, methods of preservation, periodic transfer, storage in saline suspension, storage in sterile soil, cryopreservation
Direct methods of measurement of microbial growth includes various methods of enumeration of both viable and non viable cell also includes growth curve. Helpful for UG and PG programs of microbiology
Microbial interactions are ubiquitous, diverse, critically important in the function of any biological community.
The most common cooperative interactions seen in microbial systems are mutually beneficial. The interactions between the two populations are classified according to whether both populations and one of them benefit from the associations, or one or both populations are negatively affected.
Basic Knowledge about industrial microorganism. why industry choose microorganism rather than chemical. isolation technique of microorganism. source of microorganisms. Process of using microorganism. Disadvantages of using microorganisms in industry. Process of genetic modification of microorganisms. Storage process of microorganism. preservation methods of microorganism. Reculture methods of microorganism.
Culture Collection Center National and International RinuRolly
Culture collection , Purpose of culture collection center and some famous International Culture Collection Center and National Culture Collection Centers of India .
It is a biofertilizer that contains symbiotic Rhizobium bacteria which is the most important nitrogen-fixing organism. These organisms have the ability to drive atmospheric Nitrogen and provide it to plants. It is recommended for crops such as Groundnut, Soybean, Red-gram, Green-gram, Black-gram, Lentil, Cowpea, Bengal-gram and Fodder legumes, etc.
Pure Culture Technique
Culture : Act of cultivating microorganisms or the microorganisms that are cultivated.
Mixed culture : more than one microorganism
Pure culture : containing a single species of organism.
Common isolation techniques:
1. Streak plate method
2. Pour plate method
3. Spread plate method
4. Roll tube method
In microbiology, the term isolation refers to the separation of a strain from a natural, mixed population of living microbes, as present in the environment, for example in water or soil flora, or from living beings with skin flora, oral flora or gut flora, in order to identify the microbe(s) of interest. Historically, the laboratory techniques of isolation first developed in the field of bacteriology and parasitology (during the 19th century), before those in virology during the 20th century. Methods of microbial isolation have drastically changed over the past 50 years, from a labor perspective with increasing mechanization, and in regard to the technology involved, and hence speed and accuracy.
Direct methods of measurement of microbial growth includes various methods of enumeration of both viable and non viable cell also includes growth curve. Helpful for UG and PG programs of microbiology
Microbial interactions are ubiquitous, diverse, critically important in the function of any biological community.
The most common cooperative interactions seen in microbial systems are mutually beneficial. The interactions between the two populations are classified according to whether both populations and one of them benefit from the associations, or one or both populations are negatively affected.
Basic Knowledge about industrial microorganism. why industry choose microorganism rather than chemical. isolation technique of microorganism. source of microorganisms. Process of using microorganism. Disadvantages of using microorganisms in industry. Process of genetic modification of microorganisms. Storage process of microorganism. preservation methods of microorganism. Reculture methods of microorganism.
Culture Collection Center National and International RinuRolly
Culture collection , Purpose of culture collection center and some famous International Culture Collection Center and National Culture Collection Centers of India .
It is a biofertilizer that contains symbiotic Rhizobium bacteria which is the most important nitrogen-fixing organism. These organisms have the ability to drive atmospheric Nitrogen and provide it to plants. It is recommended for crops such as Groundnut, Soybean, Red-gram, Green-gram, Black-gram, Lentil, Cowpea, Bengal-gram and Fodder legumes, etc.
Pure Culture Technique
Culture : Act of cultivating microorganisms or the microorganisms that are cultivated.
Mixed culture : more than one microorganism
Pure culture : containing a single species of organism.
Common isolation techniques:
1. Streak plate method
2. Pour plate method
3. Spread plate method
4. Roll tube method
In microbiology, the term isolation refers to the separation of a strain from a natural, mixed population of living microbes, as present in the environment, for example in water or soil flora, or from living beings with skin flora, oral flora or gut flora, in order to identify the microbe(s) of interest. Historically, the laboratory techniques of isolation first developed in the field of bacteriology and parasitology (during the 19th century), before those in virology during the 20th century. Methods of microbial isolation have drastically changed over the past 50 years, from a labor perspective with increasing mechanization, and in regard to the technology involved, and hence speed and accuracy.
PURE CULTURE TECHNIQUE ISOLATION AND IDENTIFICATION PROCESS .pptxVishekKumar8
Pure culture technique
INTRODUCTION
PURE CULTIURE TECHNIQE
ISOLATION PROCESS
STREAK PLATE METHOD
POUR PLATE METHOD
SPREAD PLATE METHOD
IDENTIFICATION PROCESS
BIOCHEMICAL TEST
MOLECULAR METHOD
SEROGICAL TECHNIQUE
Much faster rates of growth can be induced in vitro than by traditional means.
Multiplication of plants which are very difficult to propagate by cuttings or other traditional methods.
Production of large numbers of genetically identical clones in a short time
Seeds can be germinated with no risk of damping off/ predation.
Under certain conditions, plant material can be stored in vitro for considerable periods of time with little or no maintenance
Tissue culture techniques are used for virus eradication, genetic manipulation, somatic hybridization and other procedures that benefit propagation, crop improvement, and basic research.
By means of tissue culture it is possible to produce pathogen free plantlets by mass multiplication in a very limited amount of area from a very small sterile part of a mother plant. This method is also used to produce/ multiply plants that are to be transported across national border and so for their faster multiplication.But the establishment of a tissue culturing unit needs huge financial investments, skilled labors/technicians and required areas for its establishment are major constraints. Plant tissues grow and multiply in the labs only when there is an uncompetitive, growing condition with uninterrupted supply of nutrients.
Medium:
It contains all the elements that contribute the required nutrients that aid to the growth of the tissues; it is in liquid state or semi-solid in nature. The tissues are grown on the media. It consists of 95% of water, major and minor nutrients, plant growth hormones, vitamins, sugar rich compounds and chelating agents.
Totipotency:
It is the ability of a tissue or an organ of a plant to produce the whole plant, under the optional laboratory conditions and this is called as Totipotency. This is the baseline over which plant tissue culture relies upon.
Callus Culture:
When the cells divide into an undifferentiated mass it is called as callus. Any part of a plant can be used to produce the calli. It may be a stem, leaf, meristem or any other part. It is used to produce variations among the plantlets.
Suspension culture:
The callus produced from the explants are grown on nutrient solutions (that are semi solid) for a period of time and they are induced to produce plants with new traits.
Embryo Culture:
The method of culturing mature and immature embryos in media is called embryo culture. By this method, it is possible to produce plants from dormant seeds and seeds with metabolites that inhibit germination. This method is very important in crop improvement programs.
Somatic Embryogenesis:
When the plants are grown on nutrient media, calli are formed. When these calli are subjected to growth in cytokinin medium, somatic embryos are formed. They are circular, elongated,
Single cell culture
• As stated earlier, cells derived from a single cell through mitosis constitute a clone and the process of obtaining clones is called cloning (asexual progeny of a single individual make up.
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss, and a change in bowel movements. While these symptoms may indicate cancer, they can also have other causes. Over 100 types of cancers affect humans.
AAS is an analytical technique used to determine how much of certain elements are in a sample. It uses the principle that atoms (and ions) can absorb light at a specific, unique wavelength. When this specific wavelength of light is provided, the energy (light) is absorbed by the atom.
Strain improvement is one element of fermentation process management. It is the process of increasing the productivity of a microorganism by improving or selecting for a more productive phenotype.
Eukaryotic transcription is carried out in the nucleus of the cell and proceeds in three sequential stages: initiation, elongation, and termination. Eukaryotes require transcription factors to first bind to the promoter region and then help recruit the appropriate polymerase.
A mutation is a change in the DNA sequence of an organism. Mutations can result from errors in DNA replication during cell division, exposure to mutagens or a viral infection.2
A DNA vaccine is a type of vaccine that transfects a specific antigen-coding DNA sequence into the cells of an organism as a mechanism to induce an immune response.
DNA vaccines work by injecting genetically engineered plasmid containing the DNA sequence encoding the antigen(s) against which an immune response is sought, so the cells directly produce the antigen, thus causing a protective immunological response.
Bioremediation is a branch of biotechnology that employs the use of living organisms, like microbes and bacteria, in the removal of contaminants, pollutants, and toxins from soil, water, and other environments.
radioactivity is the act of emitting radiation spontaneously. This is done by an atomic nucleus that, for some reason, is unstable; it "wants" to give up some energy in order to shift to a more stable configuration.
Hypersensitivity reactions are exaggerated or inappropriate immunologic responses occurring in response to an antigen or allergen. Type I, II and III hypersensitivity reactions are known as immediate hypersensitivity reactions because they occur within 24 hours of exposure to the antigen or allergen.
Diphtheria is a serious infection caused by strains of bacteria called Corynebacterium diphtheriae that make toxin. It can lead to difficulty breathing, heart rhythm problems, and even death. CDC recommends vaccines for infants, children, teens, and adults to prevent diphtheria. Causes and How It Spreads.
Clostridium is a genus of anaerobic, Gram-positive bacteria. Species of Clostridium inhabit soils and the intestinal tract of animals, including humans. This genus includes several significant human pathogens, including the causative agents of botulism and tetanus.
transposon, class of genetic elements that can “jump” to different locations within a genome. Although these elements are frequently called “jumping genes,” they are always maintained in an integrated site in the genome. In addition, most transposons eventually become inactive and no longer move.1
Gene regulation is the process used to control the timing, location and amount in which genes are expressed. The process can be complicated and is carried out by a variety of mechanisms, including through regulatory proteins and chemical modification of DNA.
Genetic recombination (genetic reshuffling) is the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent. The process occurs naturally and can also be carried out in the lab.
Mycotoxins are naturally occurring toxins produced by certain moulds (fungi) and can be found in food.
The moulds grow on a variety of different crops and foodstuffs including cereals, nuts, spices, dried fruits, apples and coffee beans, often under warm and humid conditions.
Mycotoxins can cause a variety of adverse health effects and pose a serious health threat to both humans and livestock.
Microbiology essentially began with the development of the microscope. Although others may have seen microbes before him, it was Antonie van Leeuwenhoek, a Dutch draper whose hobby was lens grinding and making microscopes, who was the first to provide proper documentation of his observations.
We can make various products like soup powder, papad, nuggets, chips, preserve, candy etc. using different mushrooms. products like pasta, noodles etc. by supplementing with fresh or dried mushroom powder.
The microbes are highly useful for making vaccines and antibiotics for making medicines. It is a well-known fact that harmful pathogens that cause different diseases by infecting our body. The antibiotics and medicines would help us in fighting these diseases and infections.
A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. The exact definition of a genetically modified organism and what constitutes genetic engineering varies, with the most common being an organism altered in a way that "does not occur naturally by mating and/or natural recombination". A wide variety of organisms have been genetically modified (GM), from animals to plants and microorganisms.
Biofertilizers are living microbes that enhance plant nutrition by either by mobilizing or increasing nutrient availability in soils. Various microbial taxa including beneficial bacteria and fungi are currently used as biofertilizers, as they successfully colonize the rhizosphere, rhizoplane or root interior.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
1. Isolation & Preservation
of Culture of microorganism
DR. RACHANA CHOUDHARY
ASSTT. PROF. DEPT. OF MICROBIOLOGY
SHRI SHANKARACHARYA MAHAVIDYALAYA JUNWANI BHILAI
2. INTRODUCTION
• 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.
• Study the specific role played by a specific
microorganism in its environment, one must isolate the
same in pure culture.
3.
4. 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 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.
5. COMMONMETHODSOF ISOLATIONOF PURE
CULTURE
The process of screening a pure culture by separating
one type of microbes from a mixture is called
Isolation.
Common methods of isolation;
I) Streak plate method
II) Pour plate method
• Serial Dilution technique
III) Spread plate method
7. (I)STREAKINGOR STREAKPLATETECHNIQUE
• Streaking is a technique used to isolate a
pure strain from a single species of
microorganism, often bacteria. Samples can
then be taken from the resulting colonies and
a microbiological culture can be grown on a
new plate so that the organism can be
identified, studied, or tested.
10. II) Pour plate method
• The bacterial culture and liquid agar medium are
mixed together.
• After mixing the medium, the medium containing
the culture poured into sterilized petridishes
(petriplates), allowed solidifying and then
incubated.
• After incubation colonies appear on the surface.
12. Disadvantages of Pour plate method
• The microorganisms are trapped beneath the surface
of medium when it solidifies. Hence, surface as
well as subsurface colonies are developed and it is
very difficult to isolate and count the subsurface
colonies.
• This method is tedious, time consuming and requires
skill.
• The microorganisms are subjected to hot shock
because liquid medium is maintained at 45°C
temperature.
• Unsuitable for isolation of psychrophile bacteria.
14. (a) SERIAL DILUTION
This method is commonly used to obtain pure cultures of those
microorganisms that have not yet been successfully cultivated on
solid media and grow only in liquid media.
A microorganism that predominates in a mixed culture can be
isolated in pure form by a series of dilutions.
The inoculum is subjected to serial dilution in a sterile liquid
medium, and a large number of tubes of sterile liquid medium are
inoculated with aliquots of each successive dilution.
15. • If we take out 1 ml of this medium and mix it with 9 ml of fresh sterile
liquid medium, we would then have 100 microorganisms in 10 ml or 10
microorganisms/ ml.
• If we add 1 ml of this suspension to another 9 ml. of fresh sterile liquid
medium, each ml would now contain a single microorganism.
• If this tube shows any microbial growth, there is a very high probability
that this growth has resulted from the introduction of a single
microorganism in the medium and represents the pure culture of that
microorganism.
17. Advantages of spread plate method
1. It is a simple method.
2. In this method only surface colonies are
formed.
3. Micro-organisms are not exposed to
higher temperature.
18. SPECIAL METHODOF ISOLATION OF PURE CULTURE
Single cell isolation methods
(A). Capillary pipette method:
Several small drops of a suitably diluted culture
medium are put on a sterile glass-coverslip by a sterile
pipette drawn to a capillary. One then examines each
drop under the microscope until one finds such a drop,
which contains only one microorganism. This drop is
removed with a sterile capillary pipette to fresh
medium. The individual microorganism present in the
drop starts multiplying to yield a pure culture.
19.
20. (B)-MICROMANIPULATOR METHOD
Micromanipulators
Micromanipulators have been built, which permit one to pick out a
single cell from a mixed culture. This instrument is used in
conjunction with a microscope to pick a single cell (particularly
bacterial cell) from a hanging drop preparation.
ADVANTAGES OF MICROMANIPULATOR METHOD
• The advantages of this method are that one can be reasonably sure
that the cultures come from a single cell and one can obtain strains
with in the species.
DISADVANTAGES
• Disadvantages are that the equipment is expensive,
• Its manipulation is very tedious, and it requires a skilled operator.
21.
22. (2).Enrichment Culture Method:
• Generally, it is used to isolate those microorganisms, which are
present in relatively small numbers or that have slow growth rates
compared to the other species present in the mixed culture.
• The enrichment culture strategy provides a specially designed
cultural environment by incorporating a specific nutrient in the
medium and by modifying the physical conditions of the incubation.
The medium of known composition and, specific condition of
incubation favours the growth of desired microorganisms but, is
unsuitable for the growth of other types of microorganisms.
23. Maintenance and Preservation of Pure Cultures
• Once a microorganism has been isolated and grown
in pure culture, it becomes necessary to maintain
the viability and purity of the microorganism by
keeping the pure cultures free from
contamination.
Normally in laboratories, the pure cultures are
transferred periodically onto or into a fresh
medium(sub culturing) to allow continuous
growth and viability of microorganisms.
• The transfer is always subject to aseptic
conditions to avoid contamination.
24. Objectives of preservation
To maintain isolated pure cultures for
extended periods (future use) in a viable
conditions.
To avoid the contamination
To restrict genetic change(Mutation)
25. Application of Preservation
• Academic Use:
• Research Purpose:
• Fermentation Industry:
• Biotechnological Field:
• Once a microorganism has been isolated and grown in pure culture, it becomes
necessary to maintain the viability and purity of the microorganism by keeping
the pure culture free from contamination.
• Normally in laboratories, the pure cultures are transferred periodically onto or into
a fresh medium (sub-culturing) to allow continuous growth and viability of
microorganisms. The transfer is always subject to aseptic conditions to avoid
contamination.
• Since repeated sub-culturing is time consuming,
• It becomes difficult to maintain a large number of pure cultures successfully
for a long time.
• In addition, there is a risk of genetic changes as well as contamination.
• Therefore, it is now being replaced by some modern methods that do not need
frequent sub-culturing.
• These methods include refrigeration, paraffin method, cryopreservation, and
lyophilization (freeze drying).
26. Methods of Preservation
1. Periodic transfer to fresh media (Sub
culturing)
2. Storage in sterile soil
3. Storage at low temperature
4. Preservation by overlaying cultures with
mineral oil
5. Freeze dying/Lyophilization
27. 1. Periodic transfer to fresh media
• Strains can be maintained by periodically preparing a fresh culture from the
previous stock culture.
• The culture medium, the storage temperature, and the time interval at which the
transfers are made vary with the species and must be ascertained beforehand.
• The temperature and the type of medium chosen should support a slow rather than
a rapid rate of growth so that the time interval between transfers can be as long as
possible.
• Many of the more common heterotrophs remain viable for several weeks or months
on a medium like Nutrient Agar.
• The transfer method has the disadvantage of failing to prevent changes in the
characteristics of a strain due to the development of variants and mutants.
28. Advantages
1. It is a simple method, any special apparatus are not
required.
2. Easy to recover the culture
Disadvantage
1. Risk of contamination is more
2. It may be possible to change in genetic and
biochemical characteristics
29. Storagein sterilesoil
• It is mainly applied for the preservation
of sporulating microorganisms (a single
spore (endospore) within the cell).
• Fusarium, Penicillium, Alternaria,
Rhizopus, Bacillus, Aspergillus,
Penicillium, 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.
30. Storageat lowtemperature
• Culture medium can be successfully stored in
refrigerators or cold rooms, when the temperature
is maintained at 4˚C.
• Another: liquid nitrogen can provide long term
preservation of culture. In this method, dense
suspension of microbes is prepared in a medium
containing a protective agent(Glycerol or
dimethyl sulfoxide) which prevent cell damage
due to ice crystal formation. Suspension is sealed
into small ampoules or vials and then frozen at -
150°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.
• 10-30 Years without changing the characteristics.
31. Preservationby overlayingculturewith mineraloil 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.
• 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.
Adv:
• Simple
• Mainly used anaerobic microorganism
• Cost effective method
• Can preserve 10-15 years
32. 2. Lyophilization (Freeze-Drying)
• Freeze-drying is a process where water and other solvents are
removed from a frozen product via sublimation.
• Sublimation occurs when a frozen liquid goes directly to a gaseous
state without entering a liquid phase.
• It is recommended using slow rates of cooling, as this will result in
the formation of vertical ice crystal structures, thus allowing for
more efficient water sublimation for the frozen product
33.
34. Procedure
• In this process, a dense cell suspension is placed in small
vials and frozen at -60 to -70°C.
• The vial are immediately connected to a high vacuum
line.
• The ice present in the frozen suspension evaporates
(sublime) under the vacuum.
• This results in dehydration of bacterial cell and their
metabolic activities are stopped; as a result, the microbes
go into dormant state and retain viability for years.
• The vials are then sealed off under a vacuum and stored
in the dark at 4°C in refrigerators.
35. Advantage of Lyophilization
• Only minimal storage space is required; hundreds of
lyophilized cultures can be stored in a small area.
• Remained viable for more than 30 years.
• Frequent sub-culturing is not required
• Maintained without contamination
• Lyophilised strains remains genetically stable
• Small vials can be sent conveniently through the mail
to other microbiology laboratories when packaged in
a special sealed mailing containers.
• This method is employed for the preservaton of sera,
toxin, enzymes and other biologicals.
36. CONCLUSION
Pure culture maintenance technique is used for
isolation & preservation of culture from different
samples. These techniques are used for industrially
important organisms. it is essential to check the
quality of the preserved organisms stocks
However preservation is essential as it reveals great
importance in the field of science. Preservation helps
in research purposes, industry as well as in
Microbiological field.
37. REFERENCES
• Textbook of Microbiology R. P. Singh
• Textbook of Microbiology Dr. R.C.
Dubey & Dr. D. K. Maheshwari.
• Experiments in Microbiology, Plant
Pathology& Biotechnology By K.R.
Aneja.
• www.google.com
• Slidesharelink