practical 3- MSA

Question 1

what is the role of nutrient agar

Answer 1

to show how bacteria is able to grow w/o interference

Question 2

define selective media

Answer 2

this media allows some bacteria to grow while inhibiting the growth of others.

Question 3

define differential media

Answer 3

this media allows you to tell a difference (visual) between different groups of bacteria.

Question 4

what is the purpose of mannitol salt agar

Answer 4

this agar is used for isolation and differentiation of S. aureus from other staphylococcus.

Question 5

is MSA selective or differential media

Answer 5

selective because the high concentration of the agar dehydrates and kills most bacteria

Question 6

what is the ingredient in MSA that inhibits the growth of gram negative organisms

Answer 6

salt

Question 7

what differentiates S. aureus from other staph genera on the MSA plate

Answer 7

by what is able to ferment mannitol to acid end products and what cant

Question 8

does MSA grow gram positive or gram negative

Answer 8

gram positive

Question 9

what is the PH indicator used in the MSA agar

Answer 9

phenol red

Question 10

what color would pH 6.8 or below be

Answer 10

yellow

Question 11

what color would pH 7.4 - 8.4 be

Answer 11

red

Question 12

what color would pH 8.4 and above be

Answer 12

pink

Question 13

what substrate in this agar makes it differential

Answer 13

mannitol- provides the substrate for fermentation and makes the media differential

Question 14

what is the role of phenol red

Answer 14

pH indicator

Question 15

what is the role of mannitol

Answer 15

provides substrate for fermentation

Question 16

what is the role of NACL in MSA

Answer 16

makes the media selective