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19 Cards in this Set
- Front
- Back
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Coliform
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Gram-negative bacteria that ferment lactose to
produce gas; found in the intestinal tracts of animals and humans. |
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Fermentation
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The extraction of energy through anaerobic
degradation of substrates into simpler, reduced metabolites |
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Confirmed test
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Positive tubes from the highest dilution of sample
from the presumptive test are streaked onto eosin methylene blue (EMB) agar. |
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Confirmed Test
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The presence of coliform‐like colonies (small metallic green colonies with dark centers) confirms the presence of a lactose‐fermenting, gram‐negative bacterium.
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Completed test
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Dark colonies from EMB with a green, metallic
sheen are transferred to a lactose broth tube and a nutrient agar slant. |
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Completed Test
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If acid and gas are produced in the lactose broth
tube within 24 hours and a Gram stain detects a Gram-negative rod, this is considered a positive ___________. |
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Completed Test
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The water is considered contaminated with
coliforms and unsafe to drink. |
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Presumptive test
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A series of phenol red lactose broths are
inoculated with water samples. After incubation for 24-48 hours, if acid and gas are produced, it is presumed that coliforms are present in the water sample. |
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Lactose
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Carbohydrate commonly found in milk.
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Selective Media
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Favors growth of specific microorganisms & inhibits
growth of unwanted ones. |
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Differential Media
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Distinguishes between groups of microorganisms
based on different chemical reactions and appearances |
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MPN
Abbreviation for “most probable number,” |
this coliform test is used to detect the concentration of contaminants in water.
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Escherichia coli and Enterobacter species
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Which bacteria are considered the "index of fecal contamination"?
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Coliforms ferment lactose to produce acid and gas within 48 hours, while non‐coliforms do not
ferment lactose. |
What characteristic distinguishes coliforms from non‐coliforms?
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Trypticase Soy agar (TSA)
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This medium contains just the basic elemental
requirements. |
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Eosin Methylene Blue agar (EMB)
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A selective and differential medium used to isolate
fecal coliforms. |
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Trypticase Soy agar (TSA)
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It is used for saving stock cultures as well as growing organisms for various testing procedures;
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Eosin Methylene Blue agar (EMB)
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Escherichia coli will most often produce dark colonies which have a green metallic sheen, while other coliforms will produce pink or purple colonies with a mucoid appearance
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Trypticase Soy agar (TSA)
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it is a general purpose growth medium.
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