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WorksheetsIsolation Techniques and Selective Media--1
Total questions: 15
Worksheet time: 9mins
Streak Plate Methods of Isolation
identification process of an unknown microbe relies on obtaining a pure culture of that organ-
ism
method produces individual colonies on an agar plate.
density decreases, eventually leading to individual cells being deposited separately on the agar sur-
face.
A common streaking technique is the quadrant method
all of the above
Defined medium
A medium in which the chemical identity and exact amounts of all ingredients are known.
A medium in which at least one ingredient is of unknown identity or amount.
A medium that contains an inhibitor to prevent or slow the growth of undesired organisms.
A medium that is formulated in such a way that differences in the biochemistry/physiology between organisms will be detected.
Undefined
complex medium
A medium in which at least one ingredient is of unknown identity or amount.
A medium in which the chemical identity and exact amounts of all ingredients are known.
A medium that contains an inhibitor to prevent or slow the growth of undesired organisms.
A medium that is formulated in such a way that differences in the biochemistry/physiology
between organisms will be detected.
Selective medium
A medium that contains an inhibitor to prevent or slow the growth of undesired organisms.
A medium that is formulated in such a way that differences in the biochemistry/physiology between organisms will be detected.
A medium in which at least one ingredient is of unknown identity or amount.
A medium in which the chemical identity and exact amounts of all ingredients are known.
Differential medium
A medium in which the chemical identity and exact amounts of all ingredients are known.
A medium in which at least one ingredient is of unknown identity or amount.
A medium that contains an inhibitor to prevent or slow the growth of undesired organisms.
A medium that is formulated in such a way that differences in the biochemistry/physiology between organisms will be detected.
Enteric
any gut bacterium,
members of the Enterobacteriaceae,
Gram-negative rods
that ferment glucose
it detects acid or base production, depending on the medium.
Coliform
member of the Enterobacteriaceae
produces acid (and gas) from lactose fermentation.
an indicator of sulfur reduction
expose differences between organisms.
Noncoliform
A member of the Enterobacteriaceae
A member of staphylococci
does not ferment lactose.
Ferments mannose
Plays a major role in making a medium differential; it detects acid or base production, depending on the medium.
pH indicator
Bile salts (oxgall)
Lactose
Thiosulfate
Ferric ion
Used to select against organisms incapable of surviving passage through the gut, especially Gram-positives.
Bile salts (oxgall)
Lactose
Thiosulfate
Ferric ion
Used as the fermentable carbohydrate in media that differentiate between coliforms and noncoliforms.
Bile salts
Ferric ion
Lactose
Thiosulfate
Used as an electron acceptor by organisms capable of reducing sulfur to H2S.
Thiosulfate
Lactose
pH indicator
Used as an indicator of sulfur reduction by reacting with H2S to form a black precipitate.
Thiosulfate
Bile salts
Ferric ion
(BBE) Agar
used for the isolation and presumptive identification of B. fragilis
selective
differential medium
Bacteroides Bile Esculin Agar
presumptive identification of B. fragilis group.
a base medium of tryptic soy agar,
it has digests of casein (milk protein) and soybean meal.
Other anaerobes in the sample are inhibited by oxgall (bile)
includes esculin, which
B. fragilis is capable of hydrolyzing to produce esculetin.
It has no ferric ion in the medium to produce a brown coloration around B. fragilis growth
