Chemicals, Enzymes and Other Bioactive Molecules

Besides alcohol, industrial microbiology yields a range of organic acids, enzymes and pharmaceutical molecules. Organic acid producers include Aspergillus niger (citric acid), Acetobacter aceti (acetic acid), Rhizopus oryzae (fumaric acid), Clostridium butyricum (butyric acid) and various Lactobacillus species (lactic acid). Yeast (Saccharomyces cerevisiae) and bacteria are also used for commercial enzyme production: lipases are used in detergents to break down and remove oily stains from laundry; pectinase, protease and cellulase are used to clarify bottled fruit juices; and rennet is used both to curdle milk into cheese curds and more broadly in dairy processing. Several pharmaceutical bioactive molecules are also microbial products: streptokinase, produced by Streptococcus bacteria (and by genetically engineered strains), is used as a 'clot buster' to dissolve blood clots in patients recovering from a myocardial infarction (heart attack); cyclosporin A, an immunosuppressant from the fungus Trichoderma polysporum, prevents organ-transplant rejection and also has anti-inflammatory, antifungal and antiparasitic uses; statins from the yeast Monascus purpureus lower blood cholesterol by competitively inhibiting the enzyme responsible for cholesterol synthesis; and recombinant human insulin for diabetic patients is now manufactured predominantly using genetically engineered E. coli and S. cerevisiae. Biodiesel — a fuel made from vegetable oils, fats or greases that can run in ordinary diesel engines without modification, and which is non-toxic, bi …