Read the given passage and answer the following question:
Microbes like Saccharomyces cerevisiae are utilised in the commercial production of ethanol. Enzyme production is another application of microbes, with lipases being used in detergent formulations to effectively remove oily stains from laundry. It is common to observe that commercially bottled fruit juices appear clearer compared to homemade ones, as the former undergo clarification processes employing pectinases and proteases. Streptokinase, produced by the bacterium Streptococcus and genetically modified, serves as a "clot buster" in the removal of blood clots from the vessels of individuals who have experienced a heart attack. Cyclosporin A, another bioactive molecule, is derived from the fungus Trichoderma polysporum and is employed as an immunosuppressive agent in organ transplant patients. Statins, on the other hand, are produced by the yeast Monascus purpureus and have been commercialised as agents to lower blood cholesterol levels. They function by competitively inhibiting the enzyme responsible for cholesterol synthesis. Biofertilisers are organisms that enhance the nutrient quality of the soil and can be derived from bacteria, fungi, and cyanobacteria. Rhizobium bacteria form nodules on the roots of leguminous plants and convert atmospheric nitrogen into organic forms, which serve as nutrients for the plants. Additionally, certain free-living bacteria like Azospirillum and Azotobacter can fix atmospheric nitrogen in the soil, thereby enriching its nitrogen content. Fungi also engage in symbiotic associations with plants, known as mycorrhiza. Many members of the Glomus genus form mycorrhiza, wherein the fungal symbiont absorbs phosphorus from the soil and transfers it to the plant. These associations offer various benefits to the plants, including enhanced resistance to root-borne pathogens, increased tolerance to salinity and drought, and an overall improvement in plant growth and development.
Which microbe is used for the commercial production of citric acid?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Aspergillus niger
Microbes are used to make many organic acids on a commercial scale. Each acid comes from a particular microbe. Aspergillus niger, a fungus, produces citric acid. The book gives the other acid producers too: Acetobacter aceti (a bacterium) makes acetic acid, Clostridium butylicum (a bacterium) makes butyric acid, and Lactobacillus (a bacterium) makes lactic acid. The fungus in the passage, Trichoderma polysporum, makes cyclosporin A, not an acid.
NCERT Extract:
Chemicals, Enzymes and other Bioactive Molecules – “Microbes are also used for commercial and industrial production of certain chemicals like organic acids, alcohols and enzymes. Examples of acid producers are Aspergillus niger (a fungus) of citric acid, Acetobacter aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of butyric acid and Lactobacillus (a bacterium) of lactic acid.”