Quiz On Citrate, Nitrate, And Decarboxylose

Question 1

What is the citrate utilization test designed to differentiate

Answer 1

Members of the enterobacteriaceae which are facultative anaerobes

Question 2

What are facultative anaerobes?

Answer 2

Bacteria that have the ability to ferment carbohydrates and also have the ability to aerobically respire meaning they can use the citric acid cycle

Question 3

What enzymes does the citric utilization test look for

Answer 3

Citrate permease to transport citrate

Citrate lyase to hydrolyze citrate into oxaloacetate and acetate

Question 4

What is the nitrogen source in the citrate test and what does it do?

Answer 4

Ammonium it prevents complex high energy yielding respiratory processes like the citric acid cycle, but allows for citrate permease to transport citrate into the cell and perform citrate fermentation

Question 5

What does a positive citrate test look like

Answer 5

A blue color
Or it can stay green but show growth

Question 6

What bacteria are used for the citrate test?

Answer 6

Enterobacter aerogenes
E. Coli

Question 7

How do you inoculate for the citric test and how long do you incubate

Answer 7

Inoculate with a needle streaking the slants

Incubate 35 plus or minus 2° C for 48 hours

Question 8

What enzyme does the nitrate test test for in a single-step process

Answer 8

Nitrate reductase

Question 9

What are the positive indications in nitrate test

Answer 9

After inoculation gas forming is a positive

After reagents a and b are added
Turning red is a positive

If no change, zinc dust is added
If no color change is positive
After zinc is added, turning red is a negative

Question 10

How long till you incubate the nitrate test for?

Answer 10

35 plus or minus 2° C for 24 to 48 hours

Question 11

The gelatin hydrolysis test uses which enzyme

Answer 11

Gelatinases

Question 12

What is gelatin made of in the gelatin hydrolysis test

Answer 12

Gelatin
Peptone
Beef extract

Question 13

What does a positive gelatin hydrolysis test look like

Answer 13

Is a gelatin as liquid but the control is solid. Gelatinase is present

A positive can also be an organism liquefying, the gelatin in the shape of a crater

If the gelatin is solid, it’s a negative result

Question 14

How long and what temperature do you inoculate and incubate the gelatin hydrolysis test?

Answer 14

You inoculate by stabbing the test organisms into the gelatin

You incubate a 25° C for up to one week

Question 15

What bacteria do you use for the gelatin hydrolysis test

Answer 15

Bacillus septillus or b cereus
E. Coli