Monday, August 27, 2007

Microbiology

Microbiology

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An agar plate streaked with microorganisms
An agar plate streaked with microorganisms

Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms.[1] This includes eukaryotes such as fungi and protists, and prokaryotes such as bacteria and certain algae. Viruses, though not strictly classed as living organisms, are also studied.[2] Microbiology is a broad term which includes many branches like bacteriology, virology, mycology, parasitology and others. A person who specializes in the area of microbiology is called a microbiologist.

Although much is now known in the field of microbiology, advances are being made regularly. The most common estimates suggest that humans have studied only about 1% of all of the microbes in any given environment. Thus, despite the fact that over three hundred years have passed since the discovery of microbes, the field of microbiology could be said to be in its infancy relative to other biological disciplines such as zoology, botany and entomology.

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[edit] History

Bacteria were first observed by Anton van Leeuwenhoek in 1676 using a single-lens microscope of his own design.[1] The name "bacterium" was introduced much later, by Ehrenberg in 1828, derived from the Greek βακτηριον meaning "small stick". While van Leeuwenhoek is often cited as the first microbiologist, the first recorded microbiological observation, that of the fruiting bodies of molds, was made earlier in 1665 by Robert Hooke.[3]

The field of bacteriology (later a subdiscipline of microbiology) is generally considered to have been founded by Ferdinand Cohn (1828–1898), a botanist whose studies on algae and photosynthetic bacteria led him to describe several bacteria including Bacillus and Beggiatoa. Cohn was also the first to formulate a scheme for the taxonomic classification of bacteria.[4] Pasteur]] (1822–1895) and Robert Koch (1843–1910) were contemporaries of Cohn’s and are often considered to be the founders of medical microbiology.[5] Pasteur is most famous for his series of experiments designed to disprove the then widely held theory of spontaneous generation, thereby solidifying microbiology’s identity as a biological science.[6] Pasteur also designed methods for food preservation (pasteurization) and vaccines against several diseases such as anthrax, fowl cholera and rabies.[1] Koch is best known for his contributions to the germ theory of disease, proving that specific diseases were caused by specific pathogenic microorganisms. He developed a series of criteria that have become known as the Koch's postulates. Koch was one of the first scientists to focus on the isolation of bacteria in pure culture resulting in his description of several novel bacteria including Mycobacterium tuberculosis, the causative agent of tuberculosis.[1]

While Pasteur and Koch are often considered the founders of microbiology, their work did not accurately reflect the true diversity of the microbial world because of their exclusive focus on microorganisms having direct medical relevance. It was not until the work of Martinus Beijerinck (1851–1931) and Sergei Winogradsky (1856–1953), the founders of general microbiology (an older term encompassing aspects of microbial physiology, diversity and ecology), that the true breadth of microbiology was revealed.[1] Beijerinck made two major contributions to microbiology: the discovery of viruses and the development of enrichment culture techniques.[7] While his work on the Tobacco Mosaic Virus established the basic principles of virology, it was his development of enrichment culturing that had the most immediate impact on microbiology by allowing for the cultivation of a wide range of microbes with wildly different physiologies. Winogradsky was the first to develop the concept of chemolithotrophy and to thereby reveal the essential role played by microorganisms in geochemical processes.[8] He was responsible for the first isolation and description of both nitrifying and nitrogen-fixing bacteria.[1]

[edit] Types

The field of microbiology can be generally divided into several subdisciplines:

[edit] Benefits

Fermenting tanks with yeast being used to brew beer
Fermenting tanks with yeast being used to brew beer
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While microbes are often viewed negatively due to their association with many human illnesses, microbes are also responsible for many beneficial processes such as industrial fermentation (e.g. the production of alcohol and dairy products), antibiotic production and as vehicles for cloning in higher organisms such as plants. Scientists have also exploited their knowledge of microbes to produce biotechnologically important enzymes such as Taq polymerase, reporter genes for use in other genetic systems and novel molecular biology techniques such as the yeast two-hybrid system.

[edit] References

  1. ^ a b c d e f Madigan M, Martinko J (editors) (2006). Brock Biology of Microorganisms, 11th ed., Prentice Hall. ISBN 0-13-144329-1.
  2. ^ Rice G (2007-03-27). Are Viruses Alive?. Retrieved on 2007-07-23.
  3. ^ Gest H (2005). "The remarkable vision of Robert Hooke (1635-1703): first observer of the microbial world". Perspect. Biol. Med. 48 (2): 266-72. DOI:10.1353/pbm.2005.0053. PMID 15834198.
  4. ^ Drews G (1999). "Ferdinand Cohn, a Founder of Modern Microbiology". ASM News 65 (8).
  5. ^ Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0-8385-8529-9.
  6. ^ Bordenave G (2003). "Louis Pasteur (1822-1895)". Microbes Infect. 5 (6): 553-60. PMID 12758285.
  7. ^ Johnson J (1998-07-01). Martinus Willem Beijerinck. American Phytopathological Society. Retrieved on 2007-07-23.
  8. ^ Paustian T, Roberts G. Beijerinck and Winogradsky initiate the field of environmental microbiology. The Microbial World. Retrieved on 2007-07-23.

[edit] Further reading

  • Lerner, Brenda Wilmoth & K. Lee Lerner (eds) (2006). Medicine, health, and bioethics : essential primary sources, 1st ed., Thomson Gale. ISBN 1414406231.

[edit] See also

[edit] External links

Wikiversity
At Wikiversity you can learn more and teach others about Microbiology at:

[edit] General

[edit] Journals

[edit] Professional organizations

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