Question

Help me label these for Microbiology

NITRAIE PHENOL RED SUGAR DUST

Answer 1

1.Nitrate reduction test is used to differentiate the Enterobacteriaceae members on the basis of to produce nitrate reductase enzyme.

Nitrate-positive test - If the color of the medium turns red after the addition of the nitrate reagents, then the result is positive for nitrate reduction.

Nitrate Negative result- If the color of the medium does not turn red after the addition of the nitrate reagents, then another step is required and add zinc dust. If the medium turns red after the addition of the zinc dust, the result is negative in which unreduced nitrate was present.

2. Phenol red sugar- Phenol Red Broth is used to differentiate gram-negative enteric bacteria.

Positive for acid production: If the medium turns yellow means sugar is present and the result is positive.
Negative for acid production: If the medium turns red means bacteria are unable to ferment sugar.

Gas Production

Positive: If a bubble is formed then result is positive for gas production.

Negative: If no bubble is formed means no sugar is produced and the result is negative for gas production.

Methyl red- MR test is used to identify stable acid producing bacteria by the process of mixed acid fermentation of glucose.

Positive result- If the medium turns red after addition of methyl red, the result is positive.

Negative- If the medium turns yellow, then the result is negative.