Question

Which one of the following is a wrong matching of a microbe and its industrial product, while the remaining three are correct?
A. Bacillus subtilis – Statins
B. Acetobacter aceti – Acetic acid
C. Clostridum butylicum – Lactic acid
D. Aspergillus niger – Citric acid

Answer 1

Hint: Statins are the chemicals that are cholesterol lowering agents administered to people at high risk of cardiovascular diseases. Acetic acid is a widely used chemical for the preparation of plastic, printing items, textiles etc. Lactic acid is used in the cosmetic industry and the pharmaceutical industry. Citric acid is used in the food and beverage industry and also in insecticides and disinfectants.

Complete answer:
Let us look at each microbe given in the question and try and understand the different products produced by them.
Bacillus subtilis is also called hay or grass bacilli. It is a Gram-positive bacterium found in soil and gut of humans and ruminant animals. Though statins are majorly produced by strains of Penicillium and Aspergillus fungi, even B. subtilis is known to produce some amounts of statins. So, option A is right.
Next is Acetobacter aceti. It is a Gram-negative bacterium that produces acetic acid. More specifically it converts ethanol to acetic acid. Louis Pasteur was the scientist who discovered this. It lives in aerobic environments and is widely used in the fermentation industry to convert alcohol to acetic acid. Even option B is right.
The next is Clostridum butylicum, a bacterium that is used for the production of acetone and alcohol (butanol and ethanol). It uses substrates like starch, cellulose, whey and even lignin for the formation of alcohol, ether, glycerol etc. Clostridum butylicum is not known to produce lactic acid. So, option C is wrong.
The last option is Aspergillus niger. It is a fungus and is known to cause a common disease called black mold on fruits and vegetables. It is used in the industry as it produces citric acid from molasses and sugars by a process called submerged fermentation.

As we can see, the wrong option is the option C.

Note:
Lactic acid is generally produced by a genus of bacteria called Lactobacillus. It can also be produced by other bacteria such as Lactococcus spp. and other fungi such as Rhizopus spp. They use sugar as substrate to convert them into lactic acid in the industries.