Question

A newly discovered microorganism is an obligate fermenter. WHen growing in the presence of glucose, arabinose, and gluconate, which carbon source is used first, second and third and WHY?

Answer 1

As mention in question micro organisms is Obligate fermenter- it means it is obligate anaerobic organism. So it will first use glucose as carbon source, it will brake down glucose into pyruvic acid and then by mixed acid fermentation pathway or lactic acid fermentation pathway it will yield ATP and glucose will be fermented to produce acids.

When glucose in medium will exhaust , no glucose available to use then it will start utilizing Arabinose as carbon source. Arabinose operon is activated only when glucose is not available in medium. So first glucose second arabinose will be utilized and when arabinose also exhausted it will use gluconate; only remaining carbon source.