Microbes in Human Welfare

Biotechnology, in the broad sense used here, is the application of scientific and engineering principles to the processing of materials by biological agents, in order to provide goods and services for human welfare. A very wide range of microorganisms — algae, fungi, bacteria, viruses, protozoans and even nematodes — produce substances or carry out activities that are put to beneficial use for people, spanning food, health, industry, agriculture, medicine and biological pest control; this particular section focuses on how microbes are used in everyday food preparation.

Microbes in food preparation : The development of biotechnology as a whole is conventionally split into two phases: a traditional phase, running up to about 1970, based on simple fermentation carried out by naturally occurring fermenting bacteria; and a modern phase, from 1970 onward, which brought in genetic engineering and other advanced techniques. The everyday fermented foods described in this section are almost all products of the earlier, traditional phase.

1. Dosa, Dhokla and Idli : Dosa, idli and dhokla are all fermented preparations made from a batter of rice and black gram (urad dal), fermented by airborne bacteria of the genera Leuconostoc and Streptococcus. The carbon dioxide gas these bacteria release during fermentation is specifically what causes the batter to puff up, giving idlis and dhoklas their characteristic light, aerated texture.

2. Microbes as the source of food : Beyond fermenting other foods, some microbes — or, more precisely, the fruiting bodies of some fungi — are eaten directly. Mushrooms and truffles, both belonging to the higher fungi, produce large, fleshy, edible fruiting bodies that are notably sugar-free and fat-free, yet rich in proteins, vitamins, minerals and amino acids, making the food they provide comparatively low in calories for its nutritional value. In a related but distinct approach, dead and dried cells of microbes such as bacteria, algae, moulds and yeasts are processed directly as single-cell protein (SCP, covered in section 11.4), a second, non-fermentative way in which microorganisms themselves become part of the human or animal food supply.