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The primary objective of cultivating microorganisms is to maintain viable populations of these organisms under controlled ______ environments.
The primary objective of cultivating microorganisms is to maintain viable populations of these organisms under controlled ______ environments.
laboratory
All-purpose medium is ______ soy broth (TSB).
All-purpose medium is ______ soy broth (TSB).
tryptic
Enriched media contain ______ factors, vitamins, and other essential nutrients to promote the growth of fastidious organisms.
Enriched media contain ______ factors, vitamins, and other essential nutrients to promote the growth of fastidious organisms.
growth
Brain heart infusion (BHI) is made by combining an infusion from boiled bovine or porcine ______ and brain with a variety of other nutrients.
Brain heart infusion (BHI) is made by combining an infusion from boiled bovine or porcine ______ and brain with a variety of other nutrients.
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MacConkey agar contains ______ salts and crystal violet, which interfere with the growth of many gram-positive bacteria.
MacConkey agar contains ______ salts and crystal violet, which interfere with the growth of many gram-positive bacteria.
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[Blank] medium is used in the identification of bacteria and is supplemented with dyes, pH indicators, or antibiotics.
[Blank] medium is used in the identification of bacteria and is supplemented with dyes, pH indicators, or antibiotics.
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Bile salt are stored in the _______.
Bile salt are stored in the _______.
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A lobe is a part of an organ that appears to be separate in some way from the rest of the _______.
A lobe is a part of an organ that appears to be separate in some way from the rest of the _______.
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E. coli and Klebsiella spp. are lactose-fermenting organisms that grow as _______ to red colonies.
E. coli and Klebsiella spp. are lactose-fermenting organisms that grow as _______ to red colonies.
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Lactose-non-fermenting organisms, such as Salmonella, Shigella, and Proteus spp., form _______ or clear colonies.
Lactose-non-fermenting organisms, such as Salmonella, Shigella, and Proteus spp., form _______ or clear colonies.
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MUCOID means resembling _______.
MUCOID means resembling _______.
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Chocolate agar is a variant of the _______ plate.
Chocolate agar is a variant of the _______ plate.
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Red blood cell lysis gives the medium a _______________ coloration when prepared from which the agar gets its name.
Red blood cell lysis gives the medium a _______________ coloration when prepared from which the agar gets its name.
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The most common bacterial pathogens that require this enriched medium for growth include _______________ gonorrhoeae and Haemophilus species.
The most common bacterial pathogens that require this enriched medium for growth include _______________ gonorrhoeae and Haemophilus species.
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Eosin Methylene Blue (EMB) agar is a type of _______________ medium.
Eosin Methylene Blue (EMB) agar is a type of _______________ medium.
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Lactose-fermenting bacteria on EMB agar produce _______________ colonies with a green metallic sheen.
Lactose-fermenting bacteria on EMB agar produce _______________ colonies with a green metallic sheen.
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Mueller Hinton Agar (MHA) is commonly used for the routine susceptibility testing of non-fastidious microorganism by the _______________ disk diffusion technique.
Mueller Hinton Agar (MHA) is commonly used for the routine susceptibility testing of non-fastidious microorganism by the _______________ disk diffusion technique.
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A larger zone of inhibition indicates that the microorganism is _______________ to the antibiotic.
A larger zone of inhibition indicates that the microorganism is _______________ to the antibiotic.
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A ______ culture is a laboratory culture containing a single species of organism.
A ______ culture is a laboratory culture containing a single species of organism.
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A ______ is usually derived from a mixed culture by transferring a small sample into new, sterile growth medium.
A ______ is usually derived from a mixed culture by transferring a small sample into new, sterile growth medium.
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Obtaining a ______ culture of bacteria is usually accomplished by spreading bacteria on the surface of a solid medium.
Obtaining a ______ culture of bacteria is usually accomplished by spreading bacteria on the surface of a solid medium.
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Agar is an ______ substance extracted from sea algae that is used as a solidification agent.
Agar is an ______ substance extracted from sea algae that is used as a solidification agent.
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Semi-solid media are prepared to add a ______ amount of agar to observe motility of bacteria.
Semi-solid media are prepared to add a ______ amount of agar to observe motility of bacteria.
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Nutrient broth is a type of ______ used to grow bacteria.
Nutrient broth is a type of ______ used to grow bacteria.
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The spread plate technique is a method of ______ and enumeration of microorganisms in a mixed culture.
The spread plate technique is a method of ______ and enumeration of microorganisms in a mixed culture.
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Study Notes
Importance of Media for Culturing Microbes
- The primary objective of cultivating microorganisms is to maintain viable populations of these organisms under controlled laboratory environments.
- Cultivating microorganisms is a challenging process due to their highly specific nutritional and environmental requirements and the diversity of these requirements among different species.
Nutritional Requirements of Microbes
- All-purpose medium: Tryptic Soy Broth (TSB)
- Specialized media: used in the identification of bacteria and are supplemented with dyes, pH indicators, or antibiotics
- Enriched media: contains growth factors, vitamins, and other essential nutrients to promote the growth of fastidious organisms
- Chemically defined medium: complete chemical composition of a medium is known (e.g. EZ medium)
- Complex media: contain extracts and digests of yeasts, meat, or plants, and the precise chemical composition is not known (e.g. nutrient broth, TSB, Brain Heart Infusion (BHI))
Types of Media
- Selective medium: inhibits the growth of unwanted microorganisms and supports the growth of the organism of interest (e.g. MacConkey agar)
- Enrichment medium: general purpose enrichment agar that can nourish and support the growth of gram-positive as well as gram-negative bacteria (e.g. blood agar)
- Differential medium: distinguishes between different microorganisms based on their metabolic characteristics (e.g. Eosin Methylene Blue (EMB) agar)
MacConkey Agar
- Contains bile salts and crystal violet, which interfere with the growth of many gram-positive bacteria and favor the growth of gram-negative bacteria, particularly the Enterobacteriaceae
- Lactose-fermenting organisms (e.g. E. coli) grow as pink to red colonies with or without a zone of precipitated bile
- Lactose-non-fermenting organisms (e.g. Salmonella, Shigella) form colorless or clear colonies
Blood Agar
- Enriched medium that supports the growth of fastidious bacteria and inhibits the growth of some bacteria like Neisseria and Haemophilus
- Contains 5% defibrinated mammalian blood (e.g. horse, sheep, human) added to the autoclaved basal media (TSA or Columbia Agar)
Chocolate Agar
- Enriched growth medium used for the isolation of pathogenic bacteria
- Nonselective, enriched growth medium that supports the growth of fastidious bacteria
- Contains red blood cells that have been lysed by slowly heating to 80°C, releasing intracellular nutrients
Obtaining Pure Culture
- A pure culture is a laboratory culture containing a single species of organism
- Obtained by transferring a small sample into new, sterile growth medium in such a manner as to disperse the individual cells across the medium surface or by thinning the sample many fold before inoculating the new medium
- Can be accomplished by spreading bacteria on the surface of a solid medium so that a single cell occupies an isolated portion of the agar surface
Solid vs. Semi-Solid vs. Liquid Media
- Solid media: contains a solidification agent (e.g. agar) and is used for the growth of microorganisms
- Semi-solid media (deep culture): prepared with a lower concentration of agar (0.2 to 0.5%) to observe motility of bacteria
- Liquid media (broth culture): a liquid used to grow bacteria, does not contain a solidification agent
Spread Plate Technique
- A method of isolation and enumeration of microorganisms in a mixed culture
- Distributes microorganisms evenly and makes it easier to quantify bacteria in a solution
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Description
This quiz covers the importance of media for culturing microbes, methods of obtaining pure cultures, and types of media used for bacterial growth.
