Chapter 5: MICROBES IN HUMAN WELFARE
The biosphere has a variety of microorganisms that exhibit beneficial activities.
They include small algae, fungi, bacteria, protozoans, mycoplasmas and related organisms.
A large number of microbes help human civilization through their useful activities.
These activities are either of domestic, industrial or commercial importance.
The branch of Biology which deals with the study of microbes is called Microbiology.
It has several applied branches such as medical microbiology, food microbiology, industrial microbiology, etc.
5.1 MICROBES IN HOUSEHOLD PRODUCTION:
Idli, dhokala, jalebie etc. are common Indian delicacies.
The dough prepared is allowed to ferment for a couple of days.
A number of microbes are involved in their production through the process of fermentation.
The use of microbes in food production is almost as old as human civilization.
Traditionally a number of microbes from the surrounding environment are being used in production of several indigenous fermented foods.
A few examples are given below.
a) Microbes in food preparation:
The dough for dhokla is prepared by mixing gram flour (besan) with butter milk.
The lactobacilli bring about the fermentation process.
Many species of bacteria and yeast are useful in making idli and dosa.
The bubbles of CO, trapped in glutein make idlies puffy.
The microorganisms like
- species of Bacillus,
-Candida
- Saccharomyces
are involved in this process.
Many lactobacilli are involved in the preparation of jalebie, nan, etc.
b) Microbes as the source of food:
Some microbes or their fruiting bodies are directly used as a source of food, rich in protein.
The term 'SCP' or single cell protein denotes dead and dried cells of microbes like bacteria, algae, molds and yeasts.
They are obtained by growing microbes of various groups on different substrates.
These microbes include bacteria like, Bacillus subtilis, fungi like, species of Candida and Saccharomyces cerevisiae and algae such as species of Chlorella.
Mushrooms and truffles are directly used as food.
They belong to higher fungi and produce large fleshy fruiting bodies which are edible.
They are low calorie, sugar-free, fat-free but rich in proteins, vitamins, minerals and amino acids.
Some common examples of edible mushrooms are -
Common name Biological name
i) White button mushroom - Agaricus bisporus
ii) Paddy straw mushroom - Volvariella volvacea
iii) Oyster mushroom - Pleurotus florida
Some mushrooms are non-edible (poisonous) e.g.toadstools.
