Lecture 9-MT2

Question 1

What is MRS media?

Answer 1

-Selective medium
-Has sodium acetate–>Non-lactic acid bacteria CANNOT GROW

Question 2

What is Streptococcus agar?

Answer 2

-Selective medium
-has sucrose–>lactic acid bacteria CANNOT grow

Question 3

Will bacteria catabolize glucose or lactose first?

Answer 3

Glucose first
-then complex sugars (disaccharides to carbohydrates)

Question 4

Explain the fermentation test

Answer 4

a tube has protein, 1 carbohydrate, pH indicator (phenol red) is used in an inverted Durham tube
(+) = can ferment sugar–> bright yellow (6.8 or below)
(-) = cannot ferment sugar–>red (above 7.4)
(-)–>magenta (above 8.2)

Question 5

What does gas in a Durham tube mean?

Answer 5

Production of carbon dioxide

Question 6

What color will the Durham tube be for aerobic bacteria?

Answer 6

Aerobic does not do fermentation so it will never be yellow