Microbes or microorganisms are those organisms which are not visible to naked eye and can be observed only with the aid of a
microscope because they have a size of 0.1 mm or less. Microbes belong to diverse groups of organisms including bacteria, fungi,
protozoa, and microscopic plants. Viruses, viroids and prions are also included amongst microbes. Most of the microbes can be grown
on nutritive media where they form colonies, e.g., bacteria, fungi. The colonies can be seen with naked eyes.
Microbes are ubiquitous in our environment i.e., they are found in the soil, mud, water, air, body of other organisms, food products,
clothes, shoes, optical instruments, nails, skin, etc. They may occur even at places where no other organism can possibly exist, e.g.,
inside thermal vents or geysers with temperature 100°C, under several
metres thick snow where temperature is several degrees below 0°C,
highly saline or extremely acidic environment, etc.
The microorganisms influence man in several ways. Microbes are
known to cause various diseases in man and other organisms and for
deteriorating food, clothing, furniture, machinery etc. But some of their
activities are useful for us. Such activities include antibiotic production,
production of dairy products and fermented beverages, sewage treatment
etc. Useful activities of microbes can be discussed under several heading
as discussed ahead.
microbes in household products
In our household we use a variety of microbes or products obtained from them. Curd, cheese, bread etc., which are part of our daily
lives, are obtained by microbial activity.
dairy products
Dairy products include curd, yoghurt, butter milk, cheese etc.
microbes in human welfare
The content for PMT Biology is
very vast and does not allow
students to engage in inquiry
and develop meaningful
knowledge. An essential topic
for PMT is presented here to
enable students grasp the
topic, analyse the type of
questions appearing in PMTs,
and score HIGH.