Indicators

Question 1

• used in the GasPak

- white when reduced, blue when oxidized

Answer 1

methylene blue

Question 2

• used in the oxidase test
• dark blue/maroon, oxidized
• no color change, reduced

Answer 2

• positive
• negative
  p-amino-dimethylalinine monohydrochloride

Question 3

• used in carbohydrate broth, KIA agar
• yellow when acidic
• red/pink/orange when basic

Answer 3

phenol red

Question 4

• used to determine if nitrite is in a solution

- turns red if present, colorless if not

Answer 4

Nitrate A and Nitrate B reagents

Question 5

• red/pink in acidic environments

- yellow in basic environment

Answer 5

neutral red

Question 6

bile salts and crystal violet; they are nutritionally fastidious

Answer 6

what are selective components of macconkey agar and why do they inhibit G+ growth

Question 7

blue green pigment that is water soluble and tested for by Pseudosel agar

Answer 7

Pyocyanin

Question 8

A quaternary ammonium compound that inhibits growth of other pseudomonas species

Answer 8

Cetrimide

Question 9

• lime-green pigment produced by pseudomonas species
• best observed under UV light
• tested for by Pseudomonas Agar F

Answer 9

Fluorescein

Question 10

• forms red ring around top of broth when indole is present

- used in the indole test

Answer 10

Kovac’s Reagent

Question 11

• red/dark orange when acidic

- yellowish orange when neutral

Answer 11

Methyl Red

Question 12

• two reagents used in VP test

- form red layer in upper portion of the broth when reacting with diacetyl

Answer 12

Barritt’s A and Barritt’s B reagents