Microbes in Human Welfare

Notes

Introduction to Microbes

Microbes are the major components of biological systems on this Earth.

• Microbes are present everywhere – in soil, water, air, and inside the bodies of plants and animals.
• Microbes can also survive in extreme environmental conditions such as deep inside the soil, under layers of snow, and several metres deep in the oceans.
• Microorganisms are diverse and include protozoa, bacteria, fungi, microscopic plants, viruses, viroids and prions.
• Prions are proteinaceous infectious agents.

Microbes such as bacteria and many fungi can be grown on nutritive media to form colonies that can be seen with the naked eye. This is useful in the scientific study of microorganisms.

• Microbes cause many diseases in human beings, animals and plants.
• However, not all microbes are harmful.
• Several microbes are useful to humans in household products, industrial products and sewage treatment.

Microbes in Household Products

Curd

Milk is converted into curd by microorganisms such as Lactobacillus and others, commonly called Lactic Acid Bacteria (LAB).

• LAB grow in milk and convert it into curd.
• During their growth, LAB produce acids that coagulate and partially digest milk proteins.
• A small amount of curd added to fresh milk acts as an inoculum or starter.
• The starter contains millions of LAB.
• At a suitable temperature, LAB multiply and convert milk into curd.
• LAB improve the nutritional quality of curd by increasing vitamin B12.
• In our stomach, LAB also play a beneficial role by checking disease-causing microbes.

Dough

• Dough used for making foods such as dosa and idli is fermented by bacteria.
• The puffed-up appearance of dough is due to the production of CO2 gas.
• Dough used for making bread is fermented using baker's yeast, Saccharomyces cerevisiae.

Toddy

• Toddy is a traditional drink of some parts of southern India.
• It is made by fermenting sap from palm trees.

Other Fermented Foods

• Microbes are also used to ferment fish, soybean and bamboo shoots to make foods.

Cheese

• Cheese is formed by partial degradation of milk by different microorganisms.
• Different varieties of cheese are known by their characteristic texture, flavour and taste.
• These characteristics depend on the specific microbes used.
• The large holes in Swiss cheese are due to the production of a large amount of CO2 by Propionibacterium shermanii.
• Roquefort cheese is ripened by growing a specific fungus, Penicillium roqueforti, on it, which gives it a particular flavour.