This document discusses the nutritional classifications and requirements of microorganisms. It describes how bacteria can be classified based on their carbon source and energy requirements as either autotrophs or heterotrophs. Autotrophs use inorganic carbon sources while heterotrophs require organic carbon. Heterotrophs are further divided into photoheterotrophs and chemoheterotrophs based on their energy source. The document also discusses the use of defined and complex media to culture bacteria based on their nutritional needs and fastidiousness. Selective, differential, and selective-differential media are described which allow isolation and identification of bacteria based on their growth characteristics.
Bacteria cultivation NUTRITIONAL REQUIREMENTS
NUTRITIONAL TYPES OF BACTERIA
PHOTOTROPHS
CHEMOTROPHS
AUTOTROPHS AND HETEROTROPH
OBLIGATE PARASITE
BACTERIOLOGICAL MEDIA
TYPES OF MEDIA
PHYSICAL CONDITION FOR GROWTH
CULTIVATION OF AEROBIC AND ANAEROBIC BACTERIA
Bacteria cultivation NUTRITIONAL REQUIREMENTS
NUTRITIONAL TYPES OF BACTERIA
PHOTOTROPHS
CHEMOTROPHS
AUTOTROPHS AND HETEROTROPH
OBLIGATE PARASITE
BACTERIOLOGICAL MEDIA
TYPES OF MEDIA
PHYSICAL CONDITION FOR GROWTH
CULTIVATION OF AEROBIC AND ANAEROBIC BACTERIA
This presentation includes;
1.INTRODUCTION to Algae
2.HABITAT of Algae
3.SELECTION OF SOURCE- soil & Water
4.ENRICHMENT OF CULTURE- parameters
5.ISOLATION TECHNIQUES:
Establishing Unialgal culture- 6 types
Establishing Axenic culture- 4 steps
4.ISOLATION OF ALGAE FROM WATER- protocol
5.ISOLATION OF ALGAE FROM SOIL- protocol
6.CONCLUSION AND DISCUSSION
7.Reference books
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
Conventional methods for bacterial identificationMostafa Mahmoud
this lecture describes the conventional procedures for identification of bacterial colonies using different tests. the lecture is suitable for the medical students, technicians and medical staff.
This presentation includes;
1.INTRODUCTION to Algae
2.HABITAT of Algae
3.SELECTION OF SOURCE- soil & Water
4.ENRICHMENT OF CULTURE- parameters
5.ISOLATION TECHNIQUES:
Establishing Unialgal culture- 6 types
Establishing Axenic culture- 4 steps
4.ISOLATION OF ALGAE FROM WATER- protocol
5.ISOLATION OF ALGAE FROM SOIL- protocol
6.CONCLUSION AND DISCUSSION
7.Reference books
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
Conventional methods for bacterial identificationMostafa Mahmoud
this lecture describes the conventional procedures for identification of bacterial colonies using different tests. the lecture is suitable for the medical students, technicians and medical staff.
Microbiology is the study of a variety of living things, such as bacteria, fungus, and other tiny creatures, that are not visible to the naked eye. However, these little creatures are the foundation of all life on earth.. all types of living things that are invisible to the unaided eye.
Important categories have been divided based on certain traits in the study of bacteria in food. These classifications have no taxonomic relevance.
Food technology, food safety and hygiene, food poisoning, food genomics, and, more generally,
A lecture note on Microbial Growth and Nutrition, and Clones, Enzymes and Inf...Akram Hossain
This was an assignment of preparing “A lecture note on Microbial Growth and Nutrition, and Clones, Enzymes and Informative Hybridizations” for the course "General Microbiology"
Hope you will find it useful.
This presentation gives the bird's eye view of bacterial nutrition along with some other issues required to understand bacterial diversity as far as nutrition is concerned.
Micro-organisms important in Food Microbiology. Bacteria, Yeast, MoldsSt Xaviers
Here is a ppt on food microbiology. consisting information for molds, bacteria and yeast. information on types of good and bad components in each category.
Food hygiene is more than cleanliness ......
Protecting food from risk of contamination, including harmful bacteria, poison and other foreign bodies.
Preventing any bacteria present multiplying to an extent which would result in the illness of consumers or the early spoilage of the food.
Destroying any harmful bacteria in the food by thorough cooking
or processing.
Discarding unfit or contaminated food.
T-Cell Activation
• Concept of immune response
• T cell-mediated immune response
• B cell-mediated immune response
I. Concept of immune response
• A collective and coordinated response to the introduction of foreign substances in an individual mediated by the cells and molecules in the immune system.
II. T cell-mediated immune response
• Cell-mediated immunity is the arm of the adaptive immune response whose role is to combat infection of intracellular pathogens, such as intracellular bacteria (mycobacteria, listeria monocytogens), viruses, protozoa, etc.
Major Histocompatibility Complex
MHC:
• Major Histocompatibility Complex
– Cluster of genes found in all mammals
– Its products play role in discriminating self/non-self
– Participant in both humoral and cell-mediated immunity
• MHC Act As Antigen Presenting Structures
• In Human MHC Is Found On Chromosome 6
– Referred to as HLA complex
• In Mice MHC Is Found On Chromosome 17
– Referred to as H-2 complex
• Genes Of MHC Organized In 3 Classes
– Class I MHC genes
• Glycoproteins expressed on all nucleated cells
• Major function to present processed Ags to TC
– Class II MHC genes
• Glycoproteins expressed on macrophages, B-cells, DCs
• Major function to present processed Ags to TH
– Class III MHC genes
• Products that include secreted proteins that have immune functions. Ex. Complement system, inflammatory molecules
Antigen Processing and Presentation MID
Antigens and “foreignness”
• Antigens (or, more properly, immunogens) have a series of features which confer immunogenicity.
• One of these features is “foreignness.”
• So, we can infer that – most often – antigens – ultimately – originate externally.
• (There are exceptions, of course. Some cells become transformed by disease [e. g., cancer] or by aging. In such instances, the antigens have an internal origin.)
Extinction of a particular animal or plant species occurs when there are no more individuals of that species alive anywhere in the world - the species has died out. This is a natural part of evolution. But sometimes extinctions happen at a much faster rate than usual. Natural Causes of Extinction.
Difference between In-Situ and Ex-Situ conservation
Conservation of biodiversity and genetic resources helps protect, maintain and recover endangered animal and plant species. There are mainly two strategies for the conservation of wildlife: In-situ conservation and Ex-situ conservation. Although, both the strategies aim to maintain and recover endangered species, they are different from each other. Let us see how they differ from each other!
Evolution Of Bacteria
Bacteria have existed from very early in the history of life on Earth. Bacteria fossils discovered in rocks date from at least the Devonian Period (419.2 million to 358.9 million years ago), and there are convincing arguments that bacteria have been present since early Precambrian time, about 3.5 billion years ago. Bacteria were widespread on Earth at least since the latter part of the Paleoproterozoic, roughly 1.8 billion years ago, when oxygen appeared in the atmosphere as a result of the action of the cyanobacteria. Bacteria have thus had plenty of time to adapt to their environments and to have given rise to numerous descendant forms.
Impact of Environment on Loss of Genetic Diversity and Speciation
Genetic variation describes naturally occurring genetic differences among individuals of the same species. This variation permits flexibility and survival of a population in the face of changing environmental circumstances. Consequently, genetic variation is often considered an advantage, as it is a form of preparation for the unexpected. But how does genetic variation increase or decrease? And what effect do fluctuations in genetic variation have on populations over time?
GENE ENVIRONMENT INTERACTION
Subtle differences in one person’s genes can cause them to respond differently to the same environmental exposure as another person. As a result, some people may develop a disease after being exposed to something in the environment while others may not.
As scientists learn more about the connection between genes and the environment, they pursue new approaches for preventing and treating disease that consider individual genetic codes.
How to store food in hot
The Good News
To maximize benefit of preservation, keep your food as fresh as possible for as long as possible. You can do this, even in the heat, by creating a “cooler” made from two basic terra cotta pots, one larger than the other. Put the smaller pot in the larger one, fill the gap with sand, and saturate the sand with water. Then cover it with a cloth. To add additional insulation from the heat, bury the pot up to its rim. The evaporation of moisture from the wet sand will cool the air around the food and help keep it fresh.
What is IUPAC naming?
In order to give compounds a name, certain rules must be followed. When naming organic compounds, the IUPAC (International Union of Pure and Applied Chemistry) nomenclature (naming scheme) is used. This is to give consistency to the names. It also enables every compound to have a unique name, which is not possible with the common names used (for example in industry). We will first look at some of the steps that need to be followed when naming a compound, and then try to apply these rules to some specific examples.
IUPAC Nomenclature
IUPAC nomenclature uses the longest continuous chain of carbon atoms to determine the basic root name of the compound. The root name is then modified due to the presence of different functional groups which replace hydrogen or carbon atoms in the parent structure.
Hybridization describes the bonding atoms from an atom's point of view. For a tetrahedral coordinated carbon (e.g. methane CH4), the carbon should have 4 orbitals with the correct symmetry to bond to the 4 hydrogen atoms.
INTRODUCTION:
Hybrid Orbitals
Developed by Linus Pauling, the concept of hybrid orbitals was a theory created to explain the structures of molecules in space. The theory consists of combining atomic orbitals (ex: s,p,d,f) into new hybrid orbitals (ex: sp, sp2, sp3).
1. Why Firefly give light during night?
2. Why atomic mass and Atomic numbers are given to elements ?
3. Why elements have been characterized and classified into different groups?
4. What is the transition of elements and what they play their role in elements stability?
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...
media and its types
1. MEDIA CLASSIFICATION AND BACTERIAL NUTRITIONAL
REQUIREMENTS
Microorganisms are extraordinarily diverse in their requirements for growth. As
you have learned in the lectures, microorganisms are greatly affected by environmental
conditions and will grow in accordance to how these environmental niches support their
individual needs. Factors that affect microbial growth include but are not limited to, pH,
osmolarity, water activity, temperature and oxygen levels. There is a great deal of
nutritional diversity among microorganisms; therefore, microbial growth is greatly
affected by the nutrients that are available in their environment.
There are several nutritional classifications for bacteria. Autotrophs are
organisms that are able to use inorganic carbon dioxide as their sole carbon source for the
biosynthesis of macromolecules. Heterotrophs, require organic carbon for biosynthesis.
Autotrophs can be further broken down into two categories: the chemoautotrophs
derive energy from the oxidation of inorganic compounds such as iron, hydrogen sulfide
and hydrogen gas. Photoautotrophs, such as the cyanobacteria, convert light energy
into chemical energy. Heterotrophic organisms can also be divided into two major
subgroups. Photoheterotrophs, use organic carbon sources for biosynthesis but use light
energy to produce ATP (photosynthesis). Chemoheterotrophs, use organic compounds
such as sugars, proteins and lipids as their source of energy. As chemoheterotrophs are
more abundant and easier to work with, one usually works with these organisms in a
typical teaching laboratory setting. Such bacteria include but are not limited to Bacillus
subtilis, Escherichia coli and Staphylococcus aureus. Organisms of this classification
that one might encounter in a hospital setting include, the Clostridium spp. that cause
tetanus, botulism and gas gangrene, Vibrio cholerae and Streptococcus pyogenes (the
causative agent of strept throat, impetigo, scarlet fever and cellulitis, i.e. the “flesh eating
bacteria”).
The specific nutritional requirements of heterotrophic bacteria can also be quite
diverse. All microorganisms are made up of four biochemical molecules: proteins, lipids,
carbohydrates and nucleic acids; however, these organisms may differ in their individual
ability to synthesize these molecules. Some heterotrophs are metabolically flexible and
require only a few organic compounds for energy production and biosynthesis of cellular
components. Other heterotrophs require greater numbers of different organic compounds
from their environment. Organisms that fall into the latter class are called fastidious
organisms. The successful cultivation of microbes in a laboratory setting requires that
one understands the nutritional needs of an individual organism, as the absence of a
single required nutrient would prevent growth. Fastidious organisms tend to require
more ingredients in their growth media than less fastidious organisms.
The media that one uses in a laboratory setting may be classified as defined or
complex (undefined). Complex media are composed of extracts from plants, animals or
yeast and therefore are rich in nutrients. Such media is complex because the precise
individual components of these media are unknown; however, as these media contain a
wide range of nutrients that are well above the minimal nutritional requirements of the
organism being cultured, these media support the growth of a wide range of organisms.
A defined media is a media in which all of the constituents and the amounts of these
constituents are known. Defined media typically supports a narrower range of
1
2. heterotrophic microorganisms. Defined media typically consist of salts and a carbon
source in the form of glucose. Depending on the fastidiousness of an organism, these
media can be supplemented with vitamins, nucleic acids, cofactors and amino acids.
Using Selective, Differential and Selective-Differential
Media in the isolation and identification of individual
bacteria
Bacteria must be isolated from their natural environments before they can be
characterized. As bacteria exist in mixed populations in the soil, water, food and within
or on the human body, specialized media are often used to isolate individual bacteria
from these populations and to characterize the isolated bacteria.
Selective media are used to select for the growth of some bacteria while
inhibiting the growth of others. Such media take advantage of the differences in the
nutritional needs of individual bacteria or exploit the ability of some organisms to grow
in the presence of a noxious compound. For example, Pseudomonas aeruginosa is able
to grow in the presence of a variety of antibiotics (compounds that inhibit bacterial
growth or kill bacteria) while organisms like Staphylococcus aureus or Escherichia coli
are sensitive to these antibiotics.
Differential media allow a variety of organism to grow but contain substances
that allow the student to distinguish between the different types of bacteria growing on
the media.
Selective-Differential Media have characteristics of both selective media
and differential media. These media only allow a subset of bacteria to grow and allow
the student to distinguish between the different types of bacteria that are able to grow on
these media. For example, one can distinguish between bacteria that ferment lactose and
those that do not in MacConkey Agar by adding a carbon source (lactose) and a pH
indicator (methyl red)—bacteria that ferment lactose produce acids that imparts a color
change to the media surrounding the individual bacterial colony.
In the following lab exercise, each student will examine the growth characteristics
of different bacterial species on Starch Agar, MacConkey Agar, Mannitol Salt Agar
and Hektoen Enteric Agar in terms of whether the media support the growth of these
bacteria and in terms of the differences in the metabolic requirements of these bacteria.
Starch Agar: This is a differential medium used to determine whether a
given bacterium is able to use starch as a carbon source and an energy source. Starch is a
polymer (polysaccharide) of repeating glucose monomers and is too large to be
transported into the cell. Organisms that use starch produce an exoenzyme called alpha-
amylase that breaks the bonds between the glucose monomers such that the glucose
monomers can be taken up into the cell and catabolized. Alpha-amylase is secreted
outside of the cell but is still active at this location. To determine if the organism
produces this exoenzyme, one adds Gram’s Iodine to the plate that turns the intact starch
in the medium purple. If the organism utilizes starch, the area around the colony will be
2
3. clear because, the starch has been broken down into glucose monomers (starch positive).
If the organism does not utilize starch then the media surrounding the organism will be
dark purple (starch negative.
MacConkey Lactose Agar: This is a selective-differential media that
selects for the growth of enteric bacteria. Enteric bacteria are gram-negative rods that
are facultatively anaerobic. Enterics are most commonly found in the gastro-intestinal
tract of humans and include E. coli, Serratia spp. and Salmonella spp. Enterics grow on
MacConkey media because the bile salts that are present in the media inhibit the
growth of non-enteric organisms while the crystal violet inhibits the growth of Gram
positive organisms that might otherwise grow on this media. MacConkey media also
differentiates between the noncoliforms and the coliforms that also grow on this
medium. Enteric bacteria can be coliforms or noncoliforms. Enteric bacteria that
ferment lactose to form acid and gas are coliforms, enteric bacteria that do not ferment
lactose are noncoliforms. Coliforms will produce bright pink colonies on MacConkey
lactose agar because a pH indicator (methyl red) is present in the media. The non-
coliforms will grow on the media but the colonies will appear either light yellow or
colorless.
Hektoen Enteric Agar: This is also a selective-differential media that
contains bile salts to select for enteric organisms but distinguishes between these enterics
by virtue of their abilities to ferment lactose, salicin or sucrose and to reduce sulfur to
hydrogen sulfide gas. In addition to these fermentable sugars, H-E Agar contains ferric
ammonium citrate that reacts with the hydrogen sulfide to form a black precipitate and
the dyes acid fuchsin and bromothymol blue that are color indicators. This media is often
used to isolate Salmonella and Shigella spp from other enterics. The enterics that ferment
the sugars produce acids and form yellow to pink colonies on this medium. Shigella and
Salmonella spp.do not ferment these sugars and produce blue colonies. Salmonella spp.
(but not Shigella spp.) reduce sulfur to hydrogen sulfide forming colonies containing a
black precipitate.
Exercise 1: Each student will be given an organism to analyze on the aforementioned
media: The organisms in question are Staphylococcus aureus, Bacillus subtilis, Bacillus
cereus, Enterobacter aerogenes, Serratia marcescens, Shigella flexneri, Pseudomonas
aeruginosa, Klebsiella pneumoniae and Citrobacter freundii.
To analyze the organism in question streak the organism on the plates as described by the
instructor. At the next lab, record whether the organism grew and the growth behavior
of the organism. Record the results of your classmates!
3
4. Mannitol Salt Agar: Is another example of a selective differential media.
The media contains a high percentage of NaCl (7.5% w/v) to select for organisms that
prefer or can tolerate high salt conditions. Furthermore this media contains the sugar
mannitol and the pH indicator phenol red to identify the organisms that can ferment this
sugar. If the organism is able to ferment mannitol to produce acid then the pH of the
media will drop around the colonies and cause the phenol red to turn yellow. This media
is often used to isolate Staphylococcus aureus since this organism is halotolerant and able
to use mannitol as a carbon source.
Exercise 2: In this exercise each student will examine the growth characteristics of
Staphylococcus epidermidis (StE), Staphylococcus aureus (StA), Bacillus subtilis (BS)
and an isolate from the body. To this end each student will need test tubes containing one
of the three organisms and a cotton swab to isolate bacteria from their nose or other body
parts.
Divide the plate into four sectors, as shown by your instructor. Label each sector with the
organism you will inoculate into that sector. Using a loop sample each of the bacteria
individually and inoculate the bacteria into the corresponding sector. Finally, using a
sterile cotton swab, sample bacteria from your external nares and inoculate the isolate
into the fourth sector.
StE
StA
BS
Nose
sampl
e
Fill
entire
grid
4
5. Growth Characteristics of Bacteria on various
media
Starch Agar:
Staphylococcus aureus,
Bacillus subtilis,
Bacillus cereus
Enterobacter aerogenes,
Proteus mirabilis,
Serratia marcescens,
Shigella flexneri,
Pseudomonas aeruginosa,
Klebsiella pneumoniae
Citrobacter freundii
MacConkey Lactose:
Staphylococcus aureus,
Bacillus subtilis,
Enterobacter aerogenes,
5