Microbiology is the name given to the science that deals with the study of microorganisms, which are also referred to as microbes. By definition, microbes are cell-cluster or unicellular organisms which are infectious in nature, and not large enough to be seen with the naked eye. The two types of microorganisms are eukaryotes and prokaryotes. While the former has a nucleus, the latter does not have a nucleus in them. Fungi and protists are eukaryotes and bacteria are classified as prokaryotes.

Microorganisms are extremely important in everyday functioning of our lives. Some microorganisms cause a number of diseases, not only to humans but to plants and other animals as well. On the contrary, others have a very important role to play in the evolution of our environment. Microorganisms allow the fermentation of sugar to form wine and beer, as well as aid the formation of bread, cheese, and several antibiotic drugs. The contribution of microorganisms to the universe is immense, as they are responsible for disintegration of the remains of plants and animals, thereby enabling the process of recycling.

Historical Background of Microbiology

With the invention of the microscope came the science of microbiology. While microbes were seen previously too, it was Antonie van Leeuwenhoek, who was the first to document his findings related to the science. Some of his initial observations included protozoans procured from animal guts and bacteria from scrapings of teeth. The production of exceptional magnifying glasses by Antonie van Leeuwenhoek enable him to get great findings. The findings were, however, not pursued by anyone, although they generated significant interest among the scientists. He initially called the findings animalcules, and they continued to remain the quirks of nature, that baffled scientists for many generations to come. Thereafter, in the 18th century, the significance of microorganisms was acknowledged in the light of the question of whether life could also be developed from non-living material. The implications of microorganisms on nature and the welfare of humans also became evident after this period.


Basics of microbiology

There are a wide number of procedures that may be required for microbiology, in addition to a wide range of equipment. Based on the biological characteristics, microorganisms are categorized as morphology,  nutrition, physiology, reproduction and growth, pathogenesis, antigenicity, and genetic properties.


Morphology is the study of microorganisms with respect to their size, shape, and cell arrangement. The observation in morphology includes the use of microscopes, and also preparation of cells for the specific type of microbiology. While during the initial 20th century, compound microscope was used, light microscopes have been used later on.

Characteristics related to nutrition and physiology

In terms of nutritional and environmental requirements that microorganisms exhibit, microorganisms have a great diversity. While some species show growth only in solution made of inorganic salts and a carbon dioxide source, others can do with any source of carbon. The former are referred to as autotrophs, while the latter are referred to as heterotrophs. Some additional nutrients are required by some microorganisms, some of which include minerals, amino acids, and vitamins. Microorganisms are often observed to be parasites, most commonly being protozoans, fungi, and bacteria.

Reproduction and growth

The reproduction of bacteria takes place by binary fission, which is an asexual process which results in the division of a single cell into two. Given ideal conditions, bacteria have the ability divide into two every 10-15 minutes. Eukaryotic microorganisms reproduce by asexual as well as sexual methods. Some of these might also need carriers or hosts for their life cycle. Viruses, however, are produced by hosts cells, and they cannot reproduce.


The diversity of microorganisms to decompose and break down substances to simple chemicals is surprising. This is the very basis of the how the universe moves forward, and without microorganisms, life would not function the way we see it. Nitrogen fixation is a great example of their synthetic ability. It is the process of production of amino acids, proteins, and other compounds of nitrogen from nitrogen found in the atmosphere. Performing biochemical tests is an integral part of microbiology, and more so in the case of bacteria than in algae, fungi, and protozoa.


Some microorganisms are responsible for diseases in humans and animals as well as in plants. These are known as pathogens and they are identified by their hosts and common symptoms associated with them. More virulent pathogens need fewer numbers to establish an infection.


Antigen is something that stimulates the production of several substances when introduced into an animal body that unite with the antigen. The characterization of a microorganism by its antigenic properties is possible using tests that are known as serological tests.

Genetic Properties

A great deal of information has been procured on the genetic composition of cells in the last century or more, and microorganisms have had a great role to play in this. Several techniques have also been developed wherein genes from a cell have been transferred to another cell, or from animal to bacterium or bacterium to plant cell. Thus, microbiology plays a vital role in genetic engineering as well.