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describe selective media
3 examples of ingredients that select for certain types of bacteria
- contain substances that either favor the growth of particular microbes or inhibit the growth of unwanted ones
- dyes, bile salts may be added to inhibit growth of G+ bacteria, letting G- bacteria grow
Describe differential media.
3 examples of visible indicators in differential media.
- Presence of visible changes in the media
- Blood, pH indicators, Gas production
how does blood agar distinguish between alpha, beta, and gamma hemolysis?
- alpha: greenish color
- beta: clear zone around colonies
- gamma: agar unchanged
Describe MacConkey agar-
and ingredients that allow it to be both selective and differential media.
- Crystal violet: lactose, Bile salts, Neutral red
- differential media- distinguish diff. in color and selective enhance growth
Be able to interpret sugar fermentation tube results
- red= no fermentation
- yellow= acid fermentation
- bubble= gas production
what kind of media is used for obligate anaerobes; what substance is added that removes O2?
- Reducing media
- Sodium thioglycollate
What is transport media used?
- so people are not infected
- so samples are not contaminated
Give examples of microorganisms that must be grown in live animals, eggs or cells cultures.
- Leprosy and syphillis grown in animals= armadillos & rabbits
- Viruses, rickettsia, chlamydia in cells
what are candle jars used for?
- Low oxygen culture= organisms that require low levels of oxygen
- _ areotolerant anaerobes, microaerophiles, capnophiles
Explain how enrichment culture can be used to increase a microbe population
use selective media
Describe 3 ways of preserving cultures
- Refrigeration: short-term preservation
- prevents accumulation of waste
- Deep freezing: 50c to 95c
- can be stored for years
- Lyophilization: Freeze drying
- last for decades