Q.Which of the following microorganism is used for production of citric acid in industries?

Industries cultivate selected microbial strains at large scale in fermentors (bioreactors) — closed vessels with controlled aeration, agitation, temperature and pH — to manufacture antibiotics, alcoholic beverages, organic acids, enzymes and pharmaceutical molecules. Antibiotics such as penicillin (discovered by Alexander Fleming from the mould Penicillium notatum, developed by Chain and Florey), streptomycin (Streptomyces griseus) and tetracycline (Streptomyces aureofaciens) kill or inhibit disease-causing microbes; overuse drives antibiotic resistance and 'superbugs'. Yeasts, chiefly Saccharomyces cerevisiae, ferment fruit juices and malted grains into wine, beer, whisky, brandy, rum and industrial ethanol (from feedstocks like molasses, corn or wood waste). Other industrial microbial products include organic acids (Aspergillus niger → citric acid, Acetobacter aceti → acetic acid, Rhizopus oryzae → fumaric acid), enzymes (lipases, pectinase, protease, cellulase, rennet), and bioactive pharmaceuticals such as streptokinase (clot-buster), cyclosporin A (immunosuppressant, from Trichoderma polysporum), statins (from Monascus purpureus) and recombinant human insulin (from engineered E. coli/yeast).

Queries like "microbes used in industrial products list" and "microbes in industrial products class 12 biology important questions" recur around the Microbes in Human Welfare chapter of the NCERT/CBSE Class 12 Biology curriculum, a fact-dense topic that is a reliable source of NEET one-mark questions. Matching each named microbe (Penicillium, Saccharomyces, Aspergillus niger and the rest) to its specific industrial product, as tabulated here, is exactly the recall skill competitive exams test most often.