Tuesday, July 28, 2020

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

10. MICROBES IN HUMAN WELFARE

Several microbes such as bacteria, viruses, fungi etc. are useful to man in many ways. Some of them are given below:

1. 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 & 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.


2. MICROBES IN INDUSTRIAL PRODUCTS


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

Fermented beverages


-    Saccharomyces cerevisiae (Brewer’s yeast) is used in the production of beverages by fermenting malted cereals and fruit juices to produce ethanol.

-    Wine & Beer are produced without distillation.

-    Whisky, Brandy, Rum, Gin, Arrack etc. are produced by distillation of fermented broth.

Antibiotics


-    Chemical substances produced by some microbes and 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 & Florey were awarded Nobel Prize (1945).


Chemicals, enzymes & other bioactive molecules


1.    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


2.    Alcohol: Yeast (S. cerevisiae) is used to produce ethanol.


3.    Enzymes:

·   Lipases: Used in detergent formulations. Help to remove oily stains from the laundry.

·   Pectinases & 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.


4.    Cyclosporine A: Produced by Trichoderma polysporum (fungus). Used as an immunosuppressive agent in organ transplant patients.


5.    Statins: Produced by Monascus purpureus (a yeast). Used as blood-cholesterol lowering agents. It inhibits the enzymes responsible for synthesis of cholesterol.

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