lab quiz identification of unknown Bacteria

Question 1

Selective media

Answer 1

inhibits the growth of certain organisms while allowing growth of others

Question 2

Differential media

Answer 2

a visual change when certain types of bacteria are grown on them

Question 3

Eosin Methylene Blue (EMB) agar

Answer 3

-selective medium inhibits the growth of gram-postive bacteria.

-Differential medium changes color when coliform grows on it: grey, green, and pink colonies grow on the EMB agar

Question 4

MacConkey (MAC) agar

Answer 4

-agar is a selective medium that inhibits the growth of Gram-positive bacteria.

-a differential medium that changes color when coliform bacteria are grown on it.

-different enteric species may result in clear or pink colonies when grown on MAC agar

Question 5

Simmons-Citrate agar

Answer 5

-is a selective medium that allows the growth of organisms that can utilize (an intermediate of the Citric Acid Cycle) as the sole carbon source

-A differential medium that changes color from green (no growth) to blue with growth due to increased pH from alkaline byproduct of citrate utilization

Question 6

Hektoen Enetric

Answer 6

-is a selective medium that inhibits the growth of Gram-positive bacteria

-differential medium that distinguishes salmonella and shigella species from other enterics.

-Salmonella and shigella species will be dark green to black, while other gram-negative species will be pink to orange.

Question 7

Motility

Answer 7

(is another identifying feature of certain species): the ability for bacteria to move through different environments using flagella or axial filaments.

Question 8

Motility test agar

Answer 8

is where it is inoculated with a straight wire.
-Bacteria that are motile will diffuse outwards from the inoculation, whereas non-motile bacteria will grow only at the point of inoculation and on the top of the media.