Microbes are present everywhere – in soil, water, air, inside our bodies and that of other animals and plants.
Microbes in human welfare introduction
Besides macroscopic plants and animals, microbes are
the major components of biological systems on this earth.
Do you remember which Kingdoms among the living organisms contain micro-organisms?
Which are the ones that are only microscopic?
Microbes are present everywhere – in soil, water, air, inside our bodies and that of other animals and plants. Microbes are present even at sites where no other life-form could possibly exist–sites such as deep inside the geysers (thermal vents) where the temperature may be as high as 1000C, deep in the soil, under the layers of snow several metres 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 on micro-organisms.
microbes cause a large number of diseases in human beings. They also cause diseases in animals and plants.
But this should not make you think that all microbes are harmful; several microbes are useful to man in diverse ways. Some of the most important contributions of microbes to human welfare are discussed here.
MICROBES IN HOUSEHOLD PRODUCTS :
You would be surprised to know that we use microbes or products derived from them everyday. A common example is 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 diseasecausing microbes.
The dough, which is used for making foods such as dosa and idli is also fermented by bacteria. The puffed-up appearance of dough is due to the production of CO2 gas. Can you tell which metabolic pathway is taking place resulting in the formation of CO2? Where do you think the bacteria for these fermentations came from? Similarly the dough, which is used for making bread, is fermented using baker’s yeast (Saccharomyces cerevisiae). A number of traditional drinks and foods are also made by fermentation by the microbes. ‘Toddy’, a traditional drink of some parts of southern India is made by fermenting sap from palms.
Microbes are also used to ferment fish, soyabean and bamboo shoots to make foods. Cheese, is one of the oldest food items in which microbes were used. Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity coming from the microbes used.
For example, the large holes in ‘Swiss cheese’ are due to
production of a large amount of CO2 by a bacterium named Propionibacterium sharmanii.
The ‘Roquefort cheese’ are ripened by growing a specific fungi on them, which gives them a particular flavour.
MICROBES IN INDUSTRIAL PRODUCTS :
Even in industry, microbes are used to synthesise a number of products valuable to human beings.
Beverages and antibiotics are some examples.
Production on an industrial scale, requires growing microbes in very large vessels called fermentors.