Microbes in Industrial Products

Microbes are grown on a very large scale in fermenters (bioreactors) to produce useful chemicals, enzymes and medicines.

Antibiotics

Antibiotics are chemical substances produced by some microbes that kill or retard the growth of other (disease-causing) microbes. The word means 'against life' - but only against the life of the harmful microbes.

  • Penicillin was the first antibiotic to be discovered. Alexander Fleming noticed that a mould, Penicillium notatum, growing on his culture plates inhibited the growth of Staphylococci bacteria.
  • Its full potential as an effective antibiotic was established later by Ernest Chain and Howard Florey; penicillin was used to treat wounded soldiers in World War II. Fleming, Chain and Florey shared the Nobel Prize.

Antibiotics have greatly improved our ability to treat deadly infectious diseases such as plague, whooping cough, diphtheria and leprosy.

One-liners: antibiotics = microbial chemicals that kill/retard other microbes; penicillin = first antibiotic, Fleming (from Penicillium notatum, inhibiting Staphylococci), potential shown by Chain & Florey.

Chemicals, Enzymes and Bioactive Molecules

Organic acids and alcohol

Microbes are used to make several organic acids and alcohol:

  • Aspergillus niger (a fungus) -> citric acid
  • Acetobacter aceti (a bacterium) -> acetic acid
  • Clostridium butylicum (a bacterium) -> butyric acid
  • Lactobacillus (a bacterium) -> lactic acid
  • Saccharomyces cerevisiae (yeast) -> ethanol (alcohol)

Enzymes

  • Lipases are used in detergent formulations to remove oily stains.
  • Pectinases and proteases are used to clarify bottled fruit juices.
  • Streptokinase, produced by the bacterium Streptococcus and modified by genetic engineering, is used as a 'clot buster' - it removes clots from the blood vessels of patients who have had a heart attack (myocardial infarction).

Bioactive molecules

  • Cyclosporin A, produced by the fungus Trichoderma polysporum, is used as an immunosuppressive agent in organ-transplant patients.
  • Statins, produced by the yeast Monascus purpureus, are used to lower blood cholesterol. They act by competitively inhibiting the enzyme responsible for cholesterol synthesis.

One-liners: citric acid = Aspergillus niger, acetic = Acetobacter aceti, butyric = Clostridium butylicum, lactic = Lactobacillus; lipase -> detergents, pectinase/protease -> clarify juices; streptokinase (Streptococcus) = clot buster; cyclosporin A (Trichoderma polysporum) = immunosuppressant; statins (Monascus purpureus) = lower cholesterol.