Microbio Test Two

Glucose Fermentation Test

Shows glucose fermentation by indicating acid production (possibly with gas)

What are the colors for the glucose fermentation test?

The original color is red, and the positive result is yellow (with gas)

What is the medium used for the glucose fermentation test?

Phenol red broth with Durham tube

Methyl Red Voges-Proskauer Test (MR-VP)

MR: detects organisms capable of mixed acid fermentation

VP: converts acid to acetoin and 2,3 butanediol

What are the colors for the MR-VP test?

Original color is yellow, MRVP turns red if positive - with the full solution being red for the MR test, and a red ring for the VP test

What are the reagents for the MR-VP test?

MR: Methyl red

V: Barritts reagent (A and B)

What is the medium used for the MR-VP test?

MR-VP broth

Nitrate Reduction Test

Identifies anaerobic respiration using nitrogen → looking for the presence of nitrite or whether the nitrite has been reduced to nitrogen gas.

What is the medium used with the nitrate reduction test?

Nitrate broth

What colors are the nitrate broths?

Original color: clear

Presence of nitrite: red → POSITIVE TEST

Addition of zinc dust: red → NEGATIVE TEST

No reaction to zinc: clear → POSITIVE TEST

What are the reagents added to the nitrate broth?

Nitrate reagent A and B and zinc powder

Citrate Utilization Test

Identifies bacteria that can use citrate as a sole carbon source for citrate fermentation

What is the medium used with the citrate utilization test?

Simmon’s citrate slant

What color is the citrate utilization test?

Original color: green

Positive color: blue

Catalase Test

Looks for bubbling - shows breakdown of hydrogen peroxide and the production of oxygen gas

Oxidase Test