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A cluster of Escherichia coli bacteria magnified 10,000 times.

A microorganism or microbe is an organism (living thing) which is too small to be seen by the unaided human eye. They are microscopic. The study of microorganisms is called microbiology.

Microorganisms include bacteria, fungi, archaea or protists and viruses. The first four types of microorganisms may be either free-living or parasitic. Viruses, however, always reproduce inside other living things.[1][2][3]




Free-living microorganisms[change | change source]



Parasitic microbes[change | change source]

Some microbes, often called germs, cause illness or disease. They are parasites which live by invading living things. Chickenpox, mumps, and measles are all caused by viruses.[4] They are infectious diseases. Certain bacteria cause tooth decay.[4] It is possible to protect humans against some harmful microbes by storing and preparing food properly, cleaning the teeth, washing hands, and by avoiding close contact with ill people.

Commensalism[change | change source]


References[change | change source]

  1. Rybicki E.P. 1990. The classification of organisms at the edge of life, or problems with virus systematics. S African J Sci 86: 182–6.
  2. Lwoff A. 1957. The concept of virus. J. Gen. Microbiol. 17 (2): 239–53. PMID 13481308.
  3. Forterre P. 2010. Defining life: the virus viewpoint. Orig Life Evol Biosph. 40(2):151-60. [1]
  4. 4.0 4.1 4.2 Blue Planet. McGrawHill. 2003.
  5. Sears C.L. 2005. A dynamic partnership: celebrating our gut flora. Anaerobe 11 (5): 247–51. doi:10.1016/j.anaerobe.2005.05.001. PMID 16701579.

Other websites[change | change source]