Lab quiz 3

Question 1

What happens in mixed acid fermentation?

Answer 1

Bacteria ferment glucose to produce organic acids (lower pH of broth)

Question 2

What medium is used for mixed acid fermentation?

Answer 2

MR-VP medium (glucose broth)

Question 3

Explain the results of the Methyl Red Test.

Answer 3

After inoculating and incubating the broth, 3 drops of the pH indicator methyl red are added.

If the broth turns red, acid is present (positive) and the organism carried out mixed acid fermentation.

Will also generally produce gas because they produce formic hydrogenlyase.