Microorganisms that work for us
Not all microorganisms cause harm. Many bacteria, fungi and other microbes are put to work in food, medicine, agriculture and industry. Because they multiply quickly and carry out useful chemical changes, they have become one of the most valuable tools in modern science.
In food production
- Yeast (a fungus) ferments sugar to make carbon dioxide and ethanol. The gas makes bread dough rise, and the same process is used to make traditional Malaysian tapai.
- Lactobacillus bacteria turn milk into yoghurt and cheese by producing lactic acid.
- Fungi and bacteria are also used to make soy sauce, vinegar and tempeh, and cheese ripening depends on particular moulds and bacteria working over many weeks.
These food uses have been known for centuries, long before people could see the microorganisms responsible. Today the same natural processes are carried out under carefully controlled conditions of temperature and cleanliness, so that the products are safe, consistent and produced in large quantities for sale.
Key idea
In the absence of oxygen, yeast carries out fermentation: sugar → ethanol + carbon dioxide. This single reaction gives us bread, tapai and alcoholic drinks.
In medicine, farming and industry
- The fungus Penicillium produces the antibiotic penicillin, which kills harmful bacteria.
- Through genetic engineering, bacteria such as E. coli are made to produce human insulin for diabetic patients.
- Rhizobium bacteria in the root nodules of legumes fix nitrogen and enrich the soil naturally.
- Bacteria break down waste in sewage treatment and in biogas digesters, where they release methane that can be burned as fuel.
Example
On many Malaysian farms, animal dung is fed into a biogas digester. Bacteria digest the waste and produce methane gas, which is then used for cooking — turning a pollution problem into clean energy.