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Types Of Microorganisms


Microbes are tiny living creatures present everywhere around us – in water, air, food and even on the surface of our body,  on the skin, in the nose, mouth and primarily in the gastrointestinal tract.

Our environment is incomplete without these microbes, as some play an essential role in maintaining and the existence of life on the planet earth.

Microbes are small, minute organisms, which cannot be seen through our naked eye. They can be viewed or examined only under the microscope. Hence, they are also called microorganisms or microscopic organisms. These microscopic organisms are grouped in the third domain of classification as it includes both unicellular and multicellular organisms.

Microbiology is the branch of Biology involved with the scientific study of microorganisms, along with their types, features and properties.

Here, let us explore more about microbes and their types.

Five Main Types Of Microorganisms


Algae is a large, diverse group of eukaryotic, photosynthetic organisms that are either unicellular or multicellular in nature. They are free-living, eukaryotic, membrane-bound microbes, which contain photosynthetic pigments and are capable of preparing their food. Algae exist in diverse environments ranging from oceans, rivers and lakes to ponds, brackish waters and even in snow. Algae are usually green, but they can also be found in a variety of different colours including Blue-green Algae and Red Algae.


Bacteria are the very first organisms to evolve on earth; hence, these microbes are considered as one of the oldest forms of life on earth. They are prokaryotic and unicellular microorganisms, which lack a true nucleus and other membrane-bound cell organelles. The classification of bacteria is based on different criteria including, the shape, composition of the cell wall, mode of respiration and mode of nutrition. Not all bacteria are harmful and beneficial to humans. There are some bacteria, which are beneficial in different ways, including in the production of antibiotics, fermentation of food products, preparation of curd wine, etc. There are a few pathogenic bacteria, which are responsible for many of the infectious diseases, including skin infections, respiratory infections, pneumonia, tuberculosis, diphtheria, syphilis, tooth infections, etc.


Fungi are eukaryotic, unicellular organisms with true nuclei and nucleus and other membrane-bound cell organelles. Fungi are important decomposers in the ecosystem as they feed on dead and decaying organic matter. Fungi are one of the most important groups of organisms on the planet as it plays a vital role in the biosphere and has great economic importance, along with its harmful effects.


Protozoa are free-living, single-celled or multi-cellular and membrane-bound microorganisms, which are usually found in freshwater and marine environments.  These microorganisms have different modes of nutrition, most of them generally feed on dead and decaying matter.


Viruses are tiny, non-cellular microorganisms, which lack cellular structure. Viruses are considered as both living and nonliving organisms, as they are active within the host cells and inactive when they are present outside the cell. They are major causes of infectious disease in humans, plants and animals. Among the different types of microbes, both bacteria and viruses cause a majority of the diseases. These microbes have similar characteristics and the difference between virus and bacteria are based on their distinguishing features, including their shape, size, mode of nutrition, cellular organelles, mode of reproduction, mode of infections, etc.

This was a brief introduction to microbes and their types. Stay tuned with BYJU’S to learn more in detail about microbes, their facts, information and also enjoy watching various biology-related videos by subscribing to BYJU’S YouTube videos.