Microbial World

Experts believe that the naked eye — a normal eye with regular vision and unaided by any other tools — can see objects as small as about 0.1 millimeters. In this perspective, the tiniest things a human can usually see with the naked eye are things like human hair (with the naked eye and under a microscope) and lice (with the naked eye and under a microscope).

Microbiology is the study of all living organisms that are too small to be visible with the naked or unaided eye. This includes bacteria, archaea, viruses, fungi, prions, protozoa and algae, collectively known as 'microbes'.

Microorganisms are everywhere. Almost every natural surface is colonized by microbes (including our skin). Some microorganisms can live quite happily in boiling hot springs, whereas others form complex microbial communities in frozen sea ice.

Most microorganisms are harmless to humans. You swallow millions of microbes every day with no ill effects. In fact, we are dependent on microbes to help us digest our food and to protect our bodies from pathogens. Microbes also keep the biosphere running by carrying out essential functions such as the decomposition of dead animals and plants.

Microbes are the dominant form of life on planet Earth. More than half the biomass on Earth consists of microorganisms, whereas animals constitute only 15% of the mass of living organisms on Earth.

Microorganisms are defined as those organisms and acellular biological entities too small to be seen clearly by the unaided eye. They are generally 1 millimetre or less in diameter.

Although small size is an important characteristic of microbes, it alone is not sufficient to define them. Some cellular microbes, such as bread molds and filamentous photosynthetic microbes are actually visible without microscopes. These macroscopic microbes are often colonial, consisting of small aggregations of cells.

Some macroscopic microorganisms are multicellular. They are distinguished from other multicellular life forms such as plants and animals by their lack of highly differentiated tissues. Most unicellular microbes are microscopic.

However, there are interesting exceptions, cellular microbes are usually smaller than 1 millimetre in diameter, oft end unicellular and, if multicellular, lack differentiated tissues.

Microbiology deals with

• How and where they live

• Their structure

• How they derive food and energy

• Functions of soil microflora

• Role in nutrient transformation

• Relation with plant

• Importance in Industries