Microbes in Human Welfare - Notes | Class 12 | Part 1: Microbes in Household and Industrial Products

Microbes in Human Welfare

Microbes in Household Products

Lactobacillus or Lactic acid bacteria (LAB):
- It converts milk to curd by producing acids that coagulate and partially digest the milk proteins.
- Fresh milk can be converted to curd by adding some curd containing LAB. It also increases vitamin B₁₂ in curd.
- In stomach, LAB helps to check pathogens.
Bacterial fermentation (anaerobic respiration) in dough is used to make foods such as dosa, idli, etc. The puffed-up appearance of dough is due to the production of CO₂.
Baker’s Yeast (Saccharomyces cerevisiae): It is used to make bread by fermenting dough.
Toddy is made by fermenting sap from palms.
Microbes are used to ferment fish, soya bean, and bamboo-shoots and to produce cheeses.
Swiss cheese has large holes due to production of CO₂ by Propionibacterium sharmanii (a bacterium).
Roquefort cheese is ripened by growing a fungus (Penicillium roqueforti) on them.

Production of beverages, antibiotics, etc., on an industrial scale requires growing microbes in very large vessels (fermentors).

Saccharomyces cerevisiae (Brewer’s yeast) is used in the production of beverages by fermenting malted cereals and fruit juices to produce ethanol.
Wine and beer are produced without distillation.
Whisky, brandy, rum, gin, arrack, etc., are produced by distillation of fermented broth.

Chemical substances produced by some microbes that can kill or retard the growth of pathogens.
They are used to treat plague, whooping cough, diphtheria, leprosy, etc.
Penicillin: First antibiotic discovered by Alexander Fleming. He observed that Staphylococci could not grow around a mould (Penicillium notatum) growing in unwashed culture plates. He extracted penicillin from it.
Earnest Chain and Howard Florey established its full potential as an effective antibiotic.
Fleming, Chain, and Florey were awarded the Nobel Prize (1945).

Organic acids: Acid producer microbes include:
- Aspergillus niger (a fungus): Citric acid.
- Acetobacter aceti (a bacterium): Acetic acid.
- Clostridium butylicum (a bacterium): Butyric acid.
- Lactobacillus (a bacterium): Lactic acid.
Alcohol: Yeast (S. cerevisiae) is used to produce ethanol.
Enzymes:
- Lipases: Used in detergent formulations. Help to remove oily stains from the laundry.
- Pectinases and Proteases: To clarify bottled juices.
- Streptokinase: Produced by Streptococcus. Used as a ‘clot buster’ to remove clots from the blood vessels of patients who have myocardial infarction.
Cyclosporine A: Produced by Trichoderma polysporum (fungus). Used as an immunosuppressive agent in organ transplant patients.
Statins: Produced by Monascus purpureus (a yeast). Used as blood-cholesterol lowering agents. It inhibits the enzymes responsible for synthesis of cholesterol.