Biochemical testing for microbial identification - carbohydrate fermentation testing

Question 1

Define fermentation.

Answer 1

Fermentation is the conversion of pyruvic acid (the by-product of glycolysis), into an acid with or without the production of gas

Question 2

What are some common end-products of fermentation?

Answer 2

lactic acid, formic acid, acetic acid, butyric acid, ethyl alcohol, carbon dioxide, and hydrogen.

Question 3

blank is crystalline alcohol produced by many plants

Answer 3

Mannitol

Question 4

Blank is a simple carbohydrate found in fruits and vegetables

Answer 4

fructose

Question 5

Blank is a simple carbohydrate produced by plant photosynthesis and from the metabolism of glycogen in animals

Answer 5

Glucose

Question 6

T/F: Phenol red is commonly used as a pH indicator in carbohydrate fermentation tests. Phenol red turns yellow in acidic solutions

Answer 6

T

Question 7

T/F Durham tubes are used to detect the carbon dioxide and hydrogen gases that may be produced by fermentation. These small glass tubes trap gas which is visible as an air bubble.

Answer 7

T

Question 8

What are the three categories for carbohydrate fermentation?

Answer 8

Fermenter with acid production only
Fermenter with acid and gas production
Non-fermenter

Question 9

What color is fermenter, fermenter with gas, and non fermenter?

Answer 9

Orange, yellow , red

Question 10

3. How are Durham tubes used to measure gas production in carbohydrate fermentation tests?

Answer 10

Durham tubes are inverted into the phenol tubes. As a small glass tube, Durham tubes can measure gas production by trapping gas which is visible as an air bubble.