using bacterial culture A and bacterial culture B in the glu

using bacterial culture A and bacterial culture B in the glucose fermentation test you know that both cultures produce acid. Explain the fact that bacterial culture A is methyl red positive and bacterial B is methyl red negative

Solution

Methyl red test is a test used to identify bacteria producing acids during fermentation of glucose

bacteria produce pyruvic acid from glucose , some use pyruvic acid and convert them into lactic, or acetic acid. These bacteria such as in culture plate A are methyl red positive, as methyl red gives red colour at low ph.

some baceria such as in culture plate B metabolise pyruvic acid intoneutral end products, which brings down the ph to 6 and colour becomes yellow which means negative methyl red test