Question

when bacteria dont ferment the sugars they still grow by using another macromolecule in the media as an energy source resulting in the phenol red indiciator turning pink due to higher pH. typically what is this other macromolecule?

Answer 1

Genrally gram-negative bacterium are responsible to ferments the sugar like lactose in the medium like: phenol red broth (its a general-purpose commonly used differential test medium). Here phenol red is the pH indicator. In this the urea is degraded in the broth generating ammonia, resulting in rise in pH of media and it turns pink. Other macromolecules in the media are maltose, mannitol and sucrose, which truns in the monnosacchgrides and serve as the energy source.