Microbes:-
Microbes are present everywhere - in soil, water, air, inside our bodies and that of other animals and plants. They are present even at sites where no other life-form could possibly exist - sites such as deep inside the thermal vents where the temperature may be as high as 100 degree Centigrade, deep in the soil, under the layers of snow several meters thick and in highly acidic environments. Microbes are diverse - protozoa, bacteria, fungi and microscopic plant viruses, viroids and also prions that are proteinacious infectious agents.
Microbes like bacteria and many fungi can be grown on nutritive media to form colonies that can be seen with the naked eyes. Such cultures are useful in studies in micro-organisms.
Microbes In Household Products:-
We use microbes or products derived from them everyday. example- the production of curd from milk. Micro-organisms such as Lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and convert it to curd. During growth the LAB produce acids that coagulate and partially digest the milk proteins. A small amount of curd added to the fresh milk as inoculum or starter contain millions of LAB, which at suitable temperatures multiply, thus converting milk to curd, which also improves its nutritional quality by increasing vitamin B12. In our stomach too, the LAB play very beneficial role in checking disease causing microbes.
The dough which is used for making foods as dosa and idli is also fermented by bacteria. The puffed - up appearance of dough is due to the production of CO2 gas.
Microbes In Industrial Products:-
Even in industry, microbes are used to synthesise a number of products valuable to human begins. Beverages and antibiotics are some examples. Production on an industrial scale, requires growing microbes in very large vessels called fermentors.
1. Fermented Beverages:-
Microbes especially yeasts have been used from time immemorial for the production of beverages like wine, beer, whisky, brandy or rum. For this purpose the same yeast Saccharomyces cerevisiae used for bread- making and commonly called brewer's yeast is used for fermenting malted cereals and fruit juices to produce ethanol. Depending on the type of the raw material used for fermentation and the type of processing different types of alcoholic drinks are obtained. Wine and beer are produced without distillation whereas whisky, brandy and rum are produced by distillation of the fermented broth.
2. Antibiotics:-
Antibiotics produced by microbes are regarded as one of the most significant discoveries of the 20th century and have greatly contributed towards the welfare of the human society. Antibiotics are chemical substances which are produced by some microbes and can kill or retard the growth of other microbes. Antibiotics have greatly improved our capacity to treat deadly diseases such as plague, whooping cough, diptheria and leprosy which used to kill millions all over the globe.
3. Chemicals, Enzymes and other Bioactive Molecules:-
Microbes are also used for commercial and industrial production of certain chemicals like organic acids, alcohols and enzymes. Yeast is used for commercial production of ethanol. Microbes are also used for production of enzymes. Lipases are used in detergent formulations and are helpful in removing oily stains from the laundry.
Another bioactive molecule, cyclosporin A, that is used as an immunosuppressive agent in organ transplant patiets is produced by the fungus Trichoderma polysporum. Statins produced by the yeast Monascus purpureus have been commercialised as blood cholesterol lowering agents. It acys by competitively inhibiting the enzyme responsible for synthesis of cholesterol.
Microbes In Sewage Treatment:-
We know that large quantities of waste water are generated everyday in cities and towns. A major component of this waste water is human excreta. This municipal waste water is also called sewage. It contains large amounts of organic matter and microbes. Many of which are pathogenic. Treatment of waste of water is done by the heterotrophic microbes naturally present in the sewage.
Microbes In Production of Biogas:-
Bio-gas is a mixture of gases produced by the microbial activity and which may be used as fuel. Microbes produce different type of the gaseous end - products during growth and metabolism. The type other gas produced depends upon the microbes and the organic substrates they utilise. The biogas plant consists of a concrete tank in which bio wastes are collected and a slurry of dung is fed. A floating cover is placed over the slurry, which keeps on rising as the gas is produced in the tank due to the microbial activity. The biogas plant has an outlet which is connected to a pipe to supply biogas to nearby houses. The spent slurry is removed through another outlet and may be used as fertiliser. Cattle dung is available in large quantities in rural areas where cattle are used for a variety of purposes. So biogas plant are more often built in rural areas. The biogas thus produced is used for cooking and lighting .
Microbes as Biocontrol Agents:-
Biocontrol refers to the use of the biological methods for controlling plant diseases and pests. In modern society these problems have been tackled increasingly by the use of chemicals - by use of insecticides and pesticides. these chemical are toxic and extremely harmful to human beings and animals alike and have been polluting our environment fruits, vegetables and crop palnts. Our soil is also polluted through our use of weedicides to remove weeds.
A biological control being developed for use in the treatment of plant disease is the fungus Trichoderma. Trichoderma species are free living fungi that are very common in the root ecosystems. They are effective biocontrol agents of several plant pathogens.
Microbes as Biofertilisers:-
Biofertilisers are organisms that enrich the nutrient quality of the soil. The main sources of biofertilisers are bacteria, fungi and cyanobacteria. Fungi are also known to form symbiotic associations with plants. Many members of the genus glomus form mycorrhiza. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also such as resistance to root borne pathogens tolerance to salinity and drought and an overall increase in plant growth and development.
