Question

Fermentation for the industrial production of ethanol is carried out by
A) Saccharomyces
B) Lactobacillus
C) Streptomyces
D) Acetobacter

Answer 1

Hint: Ethanol fermentation is also called alcoholic fermentation. It is a biological process that converts sugars such as glucose, fructose, and sucrose into cellular energy.It produce ethanol and carbon dioxide as by-products.

Complete Answer:
1) Saccharomyces: Microbial production of one of the organic feedstocks from plant substances like molasses is presently used for ethanol production. The commercial production is carried out with Saccha­romyces cerevisiae. It starts producing ethanol at the rate of 10% (v/v).The reduction in fermentation time is accomplished use of ceil recycling continuously in fermentation. Hence, option A is correct.

2) Lactobacillus: It is the largest genus within the group of lactic acid bacteria. They are used in the manufacture of fermented dairy.Example like sourdough, meat and vegetable foods. It is also used as probiotics. Hence option B is incorrect.

3) Streptomyces: Streptomyces found predominantly in soil and decaying vegetation. It produces spores. These are characterised by a complex secondary metabolism. Hence option C is incorrect.

4) Acetobacter : It is a genus of acetic acid bacteria. In the presence of oxygen it has the ability to convert ethanol to acetic acid. It has the ability to oxidize lactate and acetate into carbon dioxide and water. Hence option D is incorrect.

Hence option ‘A’ Saccharomyces is the correct answer.

Note: Ethanol fermentation is mainly carried out with the yeast Saccharomyces cerevisiae currently in industries because of its hardiness (low pH and high ethanol tolerance).