Microbes in Human Welfare

Myocardial infarction is caused by a clot blocking a coronary blood vessel.
Streptokinase, produced by the bacterium Streptococcus and modified by genetic engineering, is used as a clot buster to remove the clot.
Statins lower blood cholesterol, penicillin is an antibiotic and cyclosporin-A is an immunosuppressant.

Statins produced by the yeast Monascus purpureus are used as blood-cholesterol lowering agents.
They act by competitively inhibiting the enzyme responsible for the synthesis of cholesterol.
Ethanol comes from Saccharomyces, streptokinase from Streptococcus and citric acid from Aspergillus niger.

Saccharomyces cerevisiae (baker's or brewer's yeast) ferments dough for bread and ferments malted cereals and fruit juices to produce ethanol for beverages such as beer.
Cheese and butter involve bacteria, citric acid comes from Aspergillus niger and lactic acid from Lactobacillus.

Trichoderma species are free-living fungi common in root ecosystems; they are effective biocontrol agents of several plant pathogens.
The lady bird beetle is an insect, not a microbe. Nucleopolyhedroviruses attack insects, not white rust (a fungal disease). Bt-cotton is a transgenic plant.

BOD is the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria.
It measures the organic matter present in sewage water: the greater the BOD, the greater the polluting potential.

The water fern Azolla harbours the cyanobacterium Anabaena azollae in its leaf cavities.
Anabaena fixes atmospheric nitrogen, so Azolla is used as a biofertiliser in paddy fields.
Frankia forms nodules on the roots of non-leguminous plants such as Alnus.

Many members of the genus Glomus form mycorrhiza, a symbiotic association of a fungus with the roots of plants.
The fungus absorbs phosphorus from the soil and passes it to the plant.
Azotobacter is a free-living nitrogen fixer and Trichoderma is a biocontrol agent.