What is a microbe or microorganism? How is it classified?« Back to Questions List


A microbe or microorganism is the oldest form of life identified. Fossils of microbes with age more than 3.5 billion years have been identified which even indicates that they existed even before dinosaurs. A microbe is a microscopic organism, millions of which can occupy the tip of a needle. It can be single cellular or multicellular. The food we eat and the air we breathe contains thousands of microorganisms. Yet we fail to see or identify them since they are so tiny and can be viewed only through highly powerful microscopes.   

Microbe, microorganism, microbiology, bacteria, virus, fungi, microscopic organism, Protists, Archaea, Virology, Epidemiology, Bacteriology


The diverse microorganisms exist in soil, water, air, atmosphere, underground, oceans, inside rocks and even inside and outside of human body. Human life is supported in many ways by these microbes. They act as decomposers and nutrient recyclers. They play important roles in biotechnology, food and beverages preparation and genetic engineering. At the same time, there are pathogenic microbes too causing diseases and even death.  

Microorganisms can be classified into mainly six groups. They are:
a.    Bacteria (back-tear-ee-uh) is a single celled microbe. While some of them cause diseases, majority are useful to human being.       They are helpful in making vitamins, decomposing and maintenance of atmosphere. 
b.    Archaea (are-key-uh) are bacteria-like creatures with some features not similar to bacteria. Some features of different varieties of   archaea are ability to withstand extremes in temperature and acidity, methane producing capability  and love for salt.
c.    Fungi(fun-jeye) include single cellular yeast to a 3.5-mile-wide mushroom, the largest known living organism on Earth. 
d.    Protists (pro-tists) include primitive algae (al-gee), amoebas (ah-me-buhs), slime molds and protozoa (pro-toe-zoh-uh).
e.    Viruses (vye-rus-is) are mainly diseases causing microbes. They are yet to be definitely confirmed as living or nonliving creatures.
f.    Microbial Mergers are microorganisms which are experts in entering into mutually beneficial collaborative arrangements. They extend some essential services to animals or humans or plants and in turn they get protected space for stay  and nutrients for growth. For example, Mycorrhizae, a fungi living in soil functions as extensions of roots of plants by supporting the nutrient absorbing capability of roots. In turn, plants provide the microbe with nutrients required for their survival. Our stomach is home for thousands of microbes that break down enzymes and acids and also make vitamins for our body. In turn, they receive nutrients from the food we eat.

Microbiology is the branch of science that study microorganism. It began after discovery of the discovery of microorganisms by Antonie Van Leeuwenhoek in 1670s. He is termed as the father of microbiology. Robert Hook, Louis Pasteur and Robert Koch are some of the prominent early names associated with microbiology.    

Different branches of microbiology are:
Bacteriology: Study of bacteria and how they help or hurt us.
Virology: Research of viruses and how they infect cells.
Mycology: Study of fungi.
Protozoology: Concentrates on protozoa.
Epidemiology: Study of infectious diseases and causes.
Immunology: Researches on the immunity mechanism of bodyagainst microbial invaders. 

Understanding microbes is crucial to learn the past and future of human life and existence planet. How does mould cause black spots on wet cloths and fruits?

How does groundwater get accumulated?
How does soap act against dirt and bacteria?