Chapter 6

Question 1

What is the objective of the indole test?

Answer 1

To see if the MO can catabolize tryptophan

Question 2

What are the products of tryptophan after tryptophanase is added?

Answer 2

Indole, pyruvate, and ammonia

Question 3

What is the indicator in an indole test, what does it indicate, and how does it indicate?

Answer 3

The indicator is Kodak’s reagent which turns bright red in the presence of indole

Question 4

What is the objective when using a Methyl Red and Voges-Proskaur test?

Answer 4

To identify different metabolic pathways used to oxidize glucose

Question 5

Butylene glycol pathways produce?

Answer 5

Acetoin and 2,3 butaneidol

Question 6

Mixed acid pathways produce?

Answer 6

Acidic ending products

Question 7

What is the indicator of methyl red, what is it indicating, how is it indicating?

Answer 7

Methyl red, will turn red if there is acid

Question 8

What is the indicator of the VP test, what is it indicating, how does it indicate this?

Answer 8

There are two indicators Barrit’s A and B and they will turn burgundy in the presence of neutral end products such as acetoin

Question 9

Citrate utilization of a MO can be determined by? Why?

Answer 9

Using a Simmons citrate medium because it is selective

Question 10

Why does the Simon citrate media change color with MO growth?

Answer 10

If the MO can utilize citrate it will also create a byproduct of ammonia which will cause the media to be more basic due to the presence of bromothylmol blue in solution

Question 11

What color is the positive and negative test of citrate utilization?

Answer 11

Positive is dark blue

Negative is green

Question 12

What is the positive and negative of all the IMViC test

Answer 12

Indole: + is red, - is original color of solution (clear)
Methyl Red: + is red, - is original color of solution (clear)
VP: + is burgundy, - is original color of solution (clear)
Citrate: + is blue, - is green

Question 13

What is Ecoli positive for?

Answer 13

indole and methyl red

Question 14

What is E. Aerogenes?

Answer 14

VP and citrate

Question 15

Why does adding hydrogen peroxide to a MO cause bubbles if it has catalase?

Answer 15

Because when catalase changed H202 into water it also produced oxygen gas

Question 16

What is cytochrome oxidase?

Answer 16

The final electron acceptor in a ETC

Question 17

How do we test for cytochrome oxidase?

Answer 17

We add a test oxidase reagent and observe to see if a purple compound forms (when in the presence of O2)

Question 18

What is wurster’s blue

Answer 18

A purple colored complex made up of chytochrome C, O2, and Test Oxidase reagent

Question 19

The EMB plate is selective and differential. T or F?

Answer 19

T

Question 20

What is the EMB selective for?

Answer 20

gram negative lactose fermenting non pathogenic MO

Question 21

What is the differential aspect of an EMB plate

Answer 21

There are dyes that react with acidic products which will be produced by colonies that ferment

Question 22

Luisetti’s media is selective and differential. T or F?

Answer 22

T

Question 23

Lusetti’s medium detects the presence of _____________

Answer 23

Fluorescein

Question 24

How do we test for motility, what is the indicator?

Answer 24

We test for motility by using in TTC, when it is oxidized it is clear but when it is taken up by the cell and reduced it is red

Question 25

Why can non motile MO still be observed to be “moving”?

Answer 25

Due to the Brownian Motion

Question 26

What is the difference between methyl red and phenol red?

Answer 26

Methyl red is an indicator of acid (red when acidic, yellow when basic)
Phenol red is an indicator of base (red when basic, yellow when acidic)

Question 27

________________: has components that inhibit growth of certain MO allowing others to grow better

Answer 27

Selective media

Question 28

_______________: allows all MO to grow but they have components that allow you to istinguish between certain groups of microbes

Answer 28

Differential media