Term
| what is the name for an organism that use organic substrates as their sources of carbon and nitrogen? |
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Definition
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Term
| name an organic compound that cannot be used by some MO? |
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Definition
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Term
| what is the name for an organic compound required by a MO that it cannot synthesize from simpler compounds? |
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Definition
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Term
| What 4 elements are required by all MO's? |
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Definition
| carbon, nitrogen, sulfur, phosphorous |
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Term
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Definition
| Potassium, calcium, iron, magnesium, sometimes sodium |
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Term
| where do proteolytic MOs acquire amino acids? |
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Definition
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Term
| what are some examples of types of growth factors? |
|
Definition
amino acids
vitamins
purines
pyrimidines
fatty acids |
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Term
| how much of broth medium in a test tube is fully aerobic? |
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Definition
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Term
| how can an anaerobic environment be created in media? |
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Definition
add reducing agent
steam media
seal w/vaspar or mineral oil
innoculate before solidified
incubate in anaerobe jar |
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Term
| name reducing agents that might be used to limit oxygen in media |
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Definition
sodium thioglycollate
cysteine
ascorbate |
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Term
| why 2 characteristics make phosphate buffers ideal for use in media? |
|
Definition
operate around 7 pH
not inhibitory to microbial growth |
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Term
| what does a phosphate buffer consist of? |
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Definition
| monohydrogen and dihydrogen phosphate |
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Term
| How do insoluble carbonates control excessive pH change? |
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Definition
| react with acid to form carbonic acid that spontaneously decomposes to H2O and CO2 |
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Term
| what are 3 ways to control excessive pH changes in media? |
|
Definition
1. add buffer
2. add insoluble carbonates
3. continuously titrate |
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|
Term
| what is a peptone? what do they provide to MOs in media? |
|
Definition
partially digested protein
nitrogen, carbon, amino acids, inorganic elements, vitamins |
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|
Term
| what peptone is produced from casein? what amino acid provided? |
|
Definition
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Term
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Definition
| a purified galactose polymer obtained from algae |
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Term
| why is agar a good choice for a solidifying agent in media? |
|
Definition
1. not metabolized by most bacteria
2. solid at temps up to 70C |
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|
Term
| what temp does agar melt? solidify? |
|
Definition
melts at 97-100C
solidifies at 42C |
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|
Term
| how is gelatin different from agar? |
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Definition
1. liquid above 25C
2. used by mmany MOs as nutrient source |
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|
Term
| what percent agar is in most media? |
|
Definition
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Term
| what solidifying agent would be used if the MO can hydrolyze agar or if organic materials are to be excluded from media? |
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Definition
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Term
| name 5 pH indicators and acid/base colors. |
|
Definition
methyl red r/y
brom cresol purple y/p
brom thymol blue y/b
phenol red y/r
phenolpthalein clear/red |
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|
Term
| why is litmus considered a dual purpose indicator? |
|
Definition
pH indicator pink/blue
OR indicator colored/colorless |
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Term
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Definition
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Term
| what types of chemicals can be used as selective agents? |
|
Definition
salt
acids
dyes
antibiotics
detergents |
|
|
Term
name a selective agent for inhibiting gm(+)
gm(-)
molds
fungi |
|
Definition
gm(+) - bile salts, penicillin, novobiocin
gm(-) - polymyxin, thallium acetate, potassium tellurite
molds - propionic, benzoic, and sorbic acids
fungus - cycloheximide, nystatin |
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|
Term
| what dyes are selectively inhibitory to some MOs? |
|
Definition
| crystal violet and brilliant green |
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|
Term
|
Definition
|
|
Term
| what are chloramphenicol and chlortetracycline? |
|
Definition
| broad range antibiotics used to inhibit bacteria |
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|
Term
| what are desoxycholate and taurocholate? |
|
Definition
|
|
Term
| what are teepol and sodium lauryl sulfate? |
|
Definition
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|
Term
| what do bile salts, penicillin, and novobiocin inhibit? |
|
Definition
|
|
Term
| what does potassium tellurite, thallium acetate, and polymyxin inhibit? |
|
Definition
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|
Term
|
Definition
| relatively pure chemicals in known concentrations |
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|
Term
| what is complex media? what types of ingredients are a clue that media is complex? |
|
Definition
one or more ingredient of unknown or variable concentration
peptones or yeast extract are examples of complex ingredients |
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|
Term
| what is the difference between a selective and a differential media? |
|
Definition
selective inhibits certain MOs
differential allows you to tell certain MOs apart b/c of growth or media rxtn. |
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|
Term
|
Definition
| all media is selective in some way |
|
|
Term
| name a differential media |
|
Definition
| MacConkey's agar (lactose fermenters red, non lactose fermenters colorless) |
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|
Term
| what are the steps to a gram stain? |
|
Definition
air dry
heat fix
crystal violet 1 min
gram's iodine 1 min
ethanol rinse
safranin 30 sec.
blot dry |
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|
Term
| what are the two general methods of enumerating microbes? |
|
Definition
|
|
Term
| what are 2 types of plate count methods? |
|
Definition
| pour plate and spread plate |
|
|
Term
| explain how to enumerate a sample with the MPN method |
|
Definition
perform serial dilutions
innoculate 3 tubes for each dilution 3
select lowest dilution that gives 3 + results
record + results of next 2 dilutions
apply to chart (divide result by 100 if per 100mL)
multiply by reciprocal of middle dilution |
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|
Term
| what does the oxidase test determine? |
|
Definition
| if the organizm has the cytochrome oxidase - can use oxygen in electron transport (respiratory metabolism) |
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|
Term
| what 2 tests should start the identification process for classifying gm- rods? |
|
Definition
oxidase test
ability to ferment glucose |
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|
Term
|
Definition
| aerobic or facultatively anaerobic, gm-, non-endospore forming rod that ferments lactose with acid and gas production w/in 48 hrs at 35C |
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|
Term
| how could you distinguish coliforms from other gr- rods? |
|
Definition
| test ability to ferment lactose with gas production |
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|
Term
| name 2 food pathogens that are gr- rods? |
|
Definition
| E.coli, Salmonella, Shigella |
|
|
Term
| name a coliform other than E.coli |
|
Definition
|
|
Term
| how would you distinguish Pseudomonas from Enterobacter? |
|
Definition
| ability to ferment glucose |
|
|
Term
| name a major psychrotrophic spoiling organisms |
|
Definition
| Pseudomonas, Alcaligenes, Flavobacterium |
|
|
Term
| what test uses Kovac's reagant? |
|
Definition
|
|
Term
| what is a positive oxidase test? |
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Definition
|
|
Term
| what test uses sulfanilic acid and dimethyl alpha-naphthylamine |
|
Definition
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|
Term
| what is a positive result for nitrites |
|
Definition
|
|
Term
| what is Nessler's reagant used for |
|
Definition
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|
Term
| what is positive nitrate result |
|
Definition
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