Question

Continuous addition of sugars in ‘fed-batch’ fermentation is done to
A. Degrade sewage
B. Produce methane
C. Degrade antibiotics
D. Purify enzymes

Answer 1

Hint: Fermentation is considered as a metabolic process through which organic molecules such as glucose are converted into acids, alcohol, or gases in the absence of oxygen or via an electron transport chain.

Complete answer:
A. Degrade sewage- Sewage treatment is done with the help of heterotrophic microbes which are already or naturally present in the sewage. This process is the removal of contaminants from the wastewater which mainly contain household wastes and industrial wastewater. These contaminants are removed either by physical, biological, or chemical processes.
B. Produce methane- Biogas is a mixture of gases (predominantly containing methane) produced due to the microbial activity and further may be used as fuel. The type of gas which is produced depends upon their microbes and substrates they utilize. Certain bacteria mainly grow anaerobically on cellulosic material which produces a large amount of methane (${\text{C}}{{\text{H}}_{\text{4}}}$) with ${\text{C}}{{\text{O}}_{\text{2}}}$(carbon dioxide) and ${{\text{H}}_{\text{2}}}$(hydrogen monohydride). Such bacteria are collectively known as methanogens.
C. Degrade antibiotics- Antibiotics are produced by the microorganism, antibiotics refer to as against life (i.e. in case of disease-causing microorganism) and in case of humans as pro-life. These are the chemical substances produced by the microbes which can retard or kill the growth of disease-causing microorganisms.
D. Purify enzymes- Fed-batch fermentation is an operational biotechnological process where one or more substrates (such as sugar/nutrients) are fed or supplied to the bioreactor during the cultivation process and in which the product remains in the bioreactor till the end product. This fed-batch process is used to purify the enzymes by continuous addition of nutrients/ sugar in the mechanism.

Hence, the correct answer is option (D).

Note: Fed-batch fermentation is a partially open system which is a semi-continuous process. It is based on feeding a growth-limiting nutrient substrate to a culture. This process is now used in all biotechnological processes particularly in the production of antibiotics and recombinant proteins.