Question

biochemical testing homework #2
please answer the following questions.

1. the reagent used in the catalase test is:

a. kovacs reagent
b. hydrogen peroxide (h₂o₂)
c. methyl red
d. barritts a and b

1. the indole test uses which reagent to detect indole production?

a. barritts reagent
b. kovacs reagent
c. nesslers reagent
d. grams iodine

1. in the methyl red (mr) test, a red color after adding methyl red indicates:

a. neutral end products
b. acidic fermentation products
c. alkaline reaction
d. presence of ammonia

1. the voges-proskauer (vp) test detects:

a. mixed acid fermentation
b. 2,3 - butanediol fermentation
c. hydrogen sulfide production
d. citrate utilization

1. the main indicator in simmons citrate agar is:

a. phenol red
b. bromothymol blue
c. neutral red
d. resazurin

Explanation:

1. In the Catalase Test, hydrogen peroxide ($\ce{H2O2}$) is used. Catalase enzyme breaks down hydrogen peroxide into water and oxygen.
2. Kovac's reagent is used in the Indole Test. It reacts with indole (produced from tryptophan by bacterial enzymes) to form a red - colored complex.
3. In the Methyl Red (MR) Test, a red color indicates acidic fermentation products. Methyl red is a pH indicator that changes color in acidic conditions.
4. The Voges - Proskauer (VP) Test detects 2,3 - butanediol fermentation. The reagents (Barrit's A and B) react with the fermentation product to give a positive result.
5. The main indicator in Simmons Citrate Agar is Bromothymol blue. It changes color based on the pH changes due to citrate utilization by bacteria.

Answer:

1. B. Hydrogen peroxide ($\ce{H2O2}$)
2. B. Kovac's reagent
3. B. Acidic fermentation products
4. B. 2,3 - butanediol fermentation
5. B. Bromothymol blue