View source for Microbiology

[[Image:Agar plate with colonies.jpg|thumb|right|An [[agar plate]] streaked with [[microorganism]]s]]
{{Science}}
'''Microbiology''' (from [[Ancient Greek|Greek]] {{lang|grc|μῑκρος}}, ''mīkros'', "small"; {{lang|grc|βίος}}, ''bios'', "[[life]]"; and {{lang|grc|-λογία}}, ''[[-logy|-logia]]'') is the study of ''[[microorganisms]]'', which are [[unicellular]] or cell-cluster [[microscopic]] [[organism]]s.<ref name=Brock>{{cite book | author = Madigan M, Martinko J (editors) | title = Brock Biology of Microorganisms | edition = 11th | publisher = Prentice Hall | year = 2006 | isbn = 0-13-144329-1 }}</ref> This includes eukaryotes such as [[fungi]] and [[protists]], and [[prokaryote]]s. [[Virus]]es<ref>{{cite web | author = Rice G | title = Are Viruses Alive? | url = http://serc.carleton.edu/microbelife/yellowstone/viruslive.html | date = 2007-03-27 |accessdate = 2007-07-23}}</ref> and [[prion]]s, though not strictly classed as living organisms, are also studied.  In short; microbiology refers to the study of life and organisms that are too small to be seen with the naked eye. Microbiology typically includes the study of the immune system, or [[Immunology]]. Generally, immune systems interact with [[pathogen]]ic microbes; these two disciplines often intersect which is why many colleges offer a paired degree such as "Microbiology and Immunology".

Microbiology is a broad term which includes [[virology]], [[mycology]], [[parasitology]], [[bacteriology]] and other branches. A [[microbiologist]] is a specialist in microbiology and these other topics.

Microbiology is researched actively, and the field is advancing continually. It is estimated only about one percent of all of the microbe species on Earth have been studied.<ref name="Amann1995">{{cite journal | author = Amann RI, Ludwig W, Schleifer KH | year = 1995 | title = Phylogenetic identification and in situ detection of individual microbial cells without cultivation | journal = Microbiol. Rev. | volume = 59 | pages = 143–169 | pmid = 7535888 | issue = 1 | pmc = 239358}}</ref> Although microbes were directly observed over three hundred years ago, the field of microbiology can be said to be in its infancy relative to older biological disciplines such as [[zoology]] and [[botany]].

==History==
===Ancient===
The existence of [[microorganism]]s was hypothesized for many centuries before their actual discovery. The existence of unseen microbiological life was postulated by [[Jainism]] which is based on [[Mahavira]]’s teachings as early as 6th century BCE.<ref>Mahavira is dated 599 BCE - 527 BC. See. {{cite book | last =Dundas | first =Paul | coauthors =John Hinnels ed. | title =The Jains | publisher =Routledge | year =2002 | location =London | isbn =0-415-26606-8 }} p. 24</ref>.  Paul Dundas notes that Mahavira asserted existence of unseen microbiological creatures living in earth, water, air and fire.<ref>Dundas, Paul (2002) p. 88</ref> [[Jain scriptures]] also describe [[nigoda]]s which are sub-microscopic creatures living in large clusters and having a very short life and are said to pervade each and every part of the universe, even in tissues of plants and flesh of animals.<ref>*{{cite book | last =Jaini | first =Padmanabh | title =The Jaina Path of Purification | publisher =Motilal Banarsidass | year =1998 | location =New Delhi | isbn =81-208-1578-5 }}  p. 109</ref> The [[Ancient Rome|Roman]] [[Marcus Terentius Varro]] made references to microbes when he warned against locating a homestead in the vicinity of swamps "because there are bred certain minute creatures which cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and there cause serious diseases."<ref>''Varro on Agriculture'' 1, xii Loeb.</ref>{{Citation needed|date=May 2010}}

In 1546 [[Girolamo Fracastoro]] proposed that [[epidemic]] [[diseases]] were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or even without contact over long distances.{{Citation needed|date=May 2010}}

However, early claims about the existence of microorganisms were [[speculative]], and not based on any data or observation. Actual observation and discovery of microbes had to await the invention of the [[microscope]] in the 17th century.

===Modern===

[[Image:Anton van Leeuwenhoek.png|thumb|right|[[Antonie van Leeuwenhoek]], known as the "father of microbiology", was the first to observe microorganisms using a microscope.]]

in 1676, [[Antonie van Leeuwenhoek]] first observed [[bacteria]] and other [[microorganisms]], using a single-lens microscope of his own design.<ref name=Brock /> While Van Leeuwenhoek is often cited as the first [[microbiologist]], [[Robert Hooke]] made the first recorded microbiological observation, of the fruiting bodies of [[mold]]s, in 1665.<ref>{{cite journal |author=Gest H |title=The remarkable vision of Robert Hooke (1635-1703): first observer of the microbial world |journal=Perspect. Biol. Med. |volume=48 |issue=2 |pages=266–72 |year=2005 |pmid=15834198 |doi=10.1353/pbm.2005.0053}}</ref>

The field of [[bacteriology]] (later a subdiscipline of microbiology) was founded in the 19th century by [[Ferdinand Cohn]], a botanist whose studies on [[algae]] and [[Phototroph|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.<ref>{{cite journal |author=Drews G |title=Ferdinand Cohn, a Founder of Modern Microbiology |journal=ASM News |volume=65 |issue=8 |page=547 |year=1999}}</ref> [[Louis Pasteur]] and [[Robert Koch]] were contemporaries of Cohn’s and are often considered to be the founders of '''[[medical microbiology]]'''.<ref name=Sherris>{{cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th | publisher = McGraw Hill | year = 2004 | isbn = 0-8385-8529-9 }}</ref> 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.<ref>{{cite journal |author=Bordenave G |title=Louis Pasteur (1822-1895) |journal=Microbes Infect. |volume=5 |issue=6 |pages=553–60 |year=2003 |pmid=12758285 |doi=10.1016/S1286-4579(03)00075-3}}</ref>  Pasteur also designed methods for food preservation ([[pasteurization]]) and vaccines against several diseases such as [[anthrax]], fowl cholera and [[rabies]].<ref name=Brock /> 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]].<ref name=Brock />

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 late 19th century and the work of [[Martinus Beijerinck]] and [[Sergei Winogradsky]], the founders of '''general microbiology''' (an older term encompassing aspects of microbial physiology, diversity and ecology), that the true breadth of microbiology was revealed.<ref name=Brock />  Beijerinck made two major contributions to microbiology: the discovery of [[virus]]es and the development of [[enrichment culture]]<!-- should this be [[Growth medium]] or [[Microbiological culture]] ? --> techniques.<ref>{{cite web | author = Johnson J | title = Martinus Willem Beijerinck | work = APSnet| publisher = American Phytopathological Society | url = http://www.apsnet.org/Education/feature/TMV/intro.html | year = 2001 |origyear = 1998 | accessdate = May 2, 2010}}</ref>  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.<ref>{{cite book | author = Paustian T, Roberts G | chapter = Beijerinck and Winogradsky Initiate the Field of Environmental Microbiology | title = Through the Microscope: A Look at All Things Small | page = §&nbsp;1–14 | nopp = y | edition = 3rd | year = 2009 | publisher = Textbook Consortia  | chapterurl = http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=32| accessdate = May 2, 2010}}</ref> He was responsible for the first isolation and description of both [[nitrifying bacteria|nitrifying]] and [[nitrogen-fixing bacteria]].<ref name=Brock />

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

* '''[[Microbial physiology]]''': The study of how the microbial cell functions biochemically. Includes the study of microbial growth, microbial [[metabolism]] and [[bacterial cell structure|microbial cell structure]].
* '''[[Microbial genetics]]''': The study of how [[gene]]s are organized and regulated in microbes in relation to their cellular functions. Closely related to the field of [[molecular biology]].
* '''[[Cellular microbiology]]''': A discipline bridging microbiology and [[cell biology]].
* '''[[Medical microbiology]]''': The study of the [[pathogenic microbes]] and the role of microbes in human illness. Includes the study of microbial [[pathogenesis]] and [[epidemiology]] and is related to the study of disease [[pathology]] and [[immunology]].
* '''[[Veterinary microbiology]]''': The study of the role in microbes in [[veterinary medicine]] or animal [[taxonomy]].
* '''[[Environmental microbiology]]''': The study of the function and diversity of microbes in their natural environments. Includes the study of [[microbial ecology]], microbially-mediated [[nutrient cycle|nutrient cycling]], [[geomicrobiology]], microbial diversity and [[bioremediation]]. Characterization of key bacterial habitats such as the [[rhizosphere]] and [[phyllosphere]], [[soil]] and [[groundwater]] [[ecosystem]]s, open [[oceans]] or extreme environments ([[extremophile]]s).
* '''[[Evolutionary microbiology]]''': The study of the evolution of microbes. Includes the study of bacterial [[systematics]] and [[taxonomy]].
* '''[[Industrial microbiology]]''': The exploitation of microbes for use in industrial processes. Examples include [[industrial fermentation]] and [[wastewater treatment]]. Closely linked to the [[biotechnology]] industry. This field also includes [[brewing]], an important application of microbiology.
* '''[[Aeromicrobiology]]''': The study of airborne microorganisms.
* '''[[Food microbiology]]''': The study of microorganisms causing food spoilage and foodborne illness.  Using microorganisms to produce foods, for example by fermentation.
* '''[[Pharmaceutical microbiology]]''': the study of microorganisms causing pharmaceutical contamination and spoil
* '''[[Agricultural microbiology]]''': The study of agriculturaly important microorganisms.
(Jobs with the Center For Disease Control and Prevention requires a degree in microbiology for most positions)
* '''[[Soil Microbiology]]''': The study of those microorganisms that are found in soil.
* '''[[Water microbiology]]''': The study of those microorganisms that are found in water.
* '''[[Generation microbiology]]''': The study of those microorganisms that have the same characters as their parents.
* '''[[Nano microbiology]]''': The study of those microorganisms at nano level.

==Benefits==
[[Image:Samadams2.jpg|thumb|right|Fermenting tanks with [[yeast]] being used to [[Brewing|brew]] [[beer]] ]]

{{Refimprovesect|date=July 2007}}

Whilst there are undoubtedly some who fear all microbes due to the association of some microbes with various human illnesses, many microbes are also responsible for numerous beneficial processes such as [[industrial fermentation]] (e.g. the production of [[alcohol]], [[vinegar]] 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 [[enzyme]]s such as [[Taq polymerase]], [[reporter gene]]s for use in other genetic systems and novel molecular biology techniques such as the [[two-hybrid screening|yeast two-hybrid system]].

Bacteria can be used for the industrial production of [[amino acid]]s. ''Corynebacterium glutamicum'' is one of the most important bacterial species with an annual production of more than two million tons of amino acids, mainly L-glutamate and L-lysine.<ref name= BurkovskiA>{{cite book | author = Burkovski A (editor). | title = Corynebacteria: Genomics and Molecular Biology | publisher = Caister Academic Press | year = 2008 | url=http://www.horizonpress.com/cory | id = [http://www.horizonpress.com/cory ISBN 978-1-904455-30-1]}}</ref>

A variety of [[biopolymer]]s, such as [[polysaccharide]]s, [[polyester]]s, and [[polyamide]]s, are produced by microorganisms. Microorganisms are used for the biotechnological production of biopolymers with tailored properties suitable for high-value medical application such as tissue engineering and drug delivery. Microorganisms are used for the biosynthesis of [[xanthan]], [[alginate]], [[cellulose]], [[cyanophycin]], poly(gamma-glutamic acid), [[levan]], [[hyaluronic acid]], organic acids, [[oligosaccharide]]s and [[polysaccharide]], and polyhydroxyalkanoates.<ref name= RehmBHA>{{cite book | author = Rehm BHA (editor). | title = Microbial Production of Biopolymers and Polymer Precursors: Applications and Perspectives | publisher = Caister Academic Press | year = 2008 | url=http://www.horizonpress.com/biopolymers | id = [http://www.horizonpress.com/biopolymers ISBN 978-1-904455-36-3]}}</ref>

Microorganisms are beneficial for [[microbial biodegradation]] or [[bioremediation]] of domestic, agricultural and industrial wastes and subsurface [[pollution]] in soils, sediments and marine environments. The ability of each microorganism to degrade [[toxic waste]] depends on the nature of each [[contaminant]]. Since sites typically have multiple pollutant types, the most effective approach to [[microbial biodegradation]] is to use a mixture of bacterial species and strains, each specific to the [[biodegradation]] of one or more types of contaminants.<ref name=Diaz>{{cite book | author = Diaz E (editor). | title = Microbial Biodegradation: Genomics and Molecular Biology | edition = 1st | publisher = Caister Academic Press | year = 2008 | url=http://www.horizonpress.com/biod | id = [http://www.horizonpress.com/biod ISBN 978-1-904455-17-2]}}</ref>

There are also various claims concerning the contributions to human and animal health by consuming [[probiotics]] (bacteria potentially beneficial to the digestive system) and/or [[prebiotics]] (substances consumed to promote the growth of probiotic microorganisms).<ref name=Tannockpro3>{{cite book | author = Tannock GW (editor). | title = Probiotics and Prebiotics: Scientific Aspects | publisher = Caister Academic Press | year = 2005 | url=http://www.horizonpress.com/pro3 | id = [http://www.horizonpress.com/pro3 ISBN 978-1-904455-01-1]}}</ref>

Recent research has suggested that microorganisms could be useful in the treatment of [[cancer]].  Various strains of non-pathogenic [[Clostridium|clostridia]] can infiltrate and replicate within solid tumors. Clostridial vectors can be safely administered and their potential to deliver therapeutic proteins has been demonstrated in a variety of preclinical models.<ref name= Mengesha>{{cite book |author= Mengesha et al.|year=2009|chapter=Clostridia in Anti-tumor Therapy |title=Clostridia: Molecular Biology in the Post-genomic Era|publisher=Caister Academic Press|isbn =  978-1-904455-38-7 }}</ref>

<!-- These traits allowed Joshua and Esther Lederberg to devise an elegant experiment in [[1951]] demonstrating that [[adaptive mutation]]s arise from [[preadaptation]] rather than [[directed mutation]]. For this purpose, they invented [[replica plating]], which allowed them to transfer numerous [[colony (biology)|bacterial colonies]] from their specific locations on one [[agar]]-filled [[petri dish]] to analogous locations on several other petri dishes. After replicating a plate of ''E. coli'', they exposed each of the new plates to a [[bacteriophage]] (also called phage). They observed that phage-resistant colonies were present at analogous locations on each of the plates, allowing them to conclude that the phage resistance trait had existed in the original colony, which had never been exposed to phage, instead of arising after the bacteria had been exposed to the virus.  <!-- This was on the page before I modified it to read more like a general description of the field of microbiology, but it just didn't seem to make sense with the rest of the page the way I wrote it. I didn't want to just throw it out, but I don't know what to do with it now! Any suggestions? -->
<br clear=all />

==See also==
{{MultiCol}}

* [[Archaea]]
* [[Bacteria]]
* [[Biochemistry]]
* [[Biosafety]]
* [[Biotechnology]]
* [[Environmental microbiology]]
* [[Eukaryote]]

{{ColBreak}}

* [[Food microbiology]]
* [[Genetics]]
* [[Immunology]]
* [[List of publications in biology#Microbiology|Important publications in microbiology]]
* [[Industrial microbiology]]
* [[Iron in microbiology]]
* [[List of Microbiological topics]] 
* [[Microbial phylogenetics]]

{{ColBreak}}

* [[Medical technologist]]
* [[Medicine]]
* [[Mycology]]
* [[Oral microbiology]]
* [[Phage meetings|Bacteriophage meetings]]
* [[Prokaryote]]
* [[Virology]]

{{EndMultiCol}}

==References==
<!-- ---------------------------------------------------------------
See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for a
discussion of different citation methods and how to generate
footnotes using the <ref> & </ref> tags and the {{Reflist}} template
-------------------------------------------------------------------- -->

{{Reflist|2}}

<!--
===Further reading===
<div class="references-small">

* {{cite book | author = Lerner, Brenda Wilmoth & K. Lee Lerner (eds) | title = Medicine, health, and bioethics : essential primary sources | edition = 1st | publisher = Thomson Gale | year = 2006 | isbn = 1414406231 }}
* {{cite book | author = Witzany, Guenther | title = Biocommunication and Natural Genome Editing | publisher = Springer | year = 2010 }}
</div>
-->

==References==
{{Reflist}}

==External links==
{{WVD}}

===General===
* [http://media.med.sc.edu/microbiology2007/ Online lectures in microbiology] University of South Carolina
* [http://www.ocean.edu/academics/programs_of_study/science/MicrobiologyOnline.htm Microbiology Online]
* [http://www.microbiologytext.com/index.php?module=Book&func=toc&book_id=4 Online Microbiology textbook]
* [http://www.textbookofbacteriology.net/ Todar's Bacteriology textbook]
* [http://pathmicro.med.sc.edu/book/welcome.htm Online Medical Microbiology textbook]
* [http://www.micro.biol.ethz.ch/ Institute of Microbiology of the Swiss Federal Institute of Technology]

===Journals===
* [http://arjournals.annualreviews.org/loi/micro/ Annual Review of Microbiology]
* [[Critical Reviews in Microbiology]] ([http://www.informaworld.com/crmicrobiology journal home])
* [[International Journal of Systematic and Evolutionary Microbiology]]
* [[Journal of Bacteriology]]
* [[Nature Reviews Microbiology]] ([http://www.nature.com/nrmicro/index.html journal home])
* [[Springer Protocols]] in Microbiology
* [http://www.microbiology-journal.com/ Microbiology Journal] Descriptions and summarys of a wide range of journals in all areas of microbiology

===Professional organizations===
* [http://www.microbiologystudents.com/ '''Microbiology Students Portal''']
* [http://www.asm.org/ American Society for Microbiology]
* [http://www.socgenmicrobiol.org.uk/ Society for General Microbiology]
* [http://www.simhq.org/ Society for Industrial Microbiology]

{{Biology-footer}}

{{Bacteria}}

{{Virus topics}}

{{Fungus}}
{{Protozoa protist}}

[[Category:Microbiology]]
[[Category:Subjects taught in medical school]]

{{Link FA|hi}}

[[af:Mikrobiologie]]
[[ar:علم الأحياء الدقيقة]]
[[an:Microbiolochía]]
[[ast:Microbioloxía]]
[[bs:Mikrobiologija]]
[[bg:Микробиология]]
[[ca:Microbiologia]]
[[cs:Mikrobiologie]]
[[cy:Microfioleg]]
[[da:Mikrobiologi]]
[[de:Mikrobiologie]]
[[et:Mikrobioloogia]]
[[el:Μικροβιολογία]]
[[es:Microbiología]]
[[eo:Mikrobiologio]]
[[eu:Mikrobiologia]]
[[fa:میکروبیولوژی]]
[[fo:Smáverulívfrøði]]
[[fr:Microbiologie]]
[[ga:Micribhitheolaíocht]]
[[gv:Myn-vioagh-oaylleeaght]]
[[gl:Microbioloxía]]
[[ko:미생물학]]
[[hi:सूक्ष्मजैविकी]]
[[hr:Mikrobiologija]]
[[ilo:Microbiolohia]]
[[id:Mikrobiologi]]
[[is:Örverufræði]]
[[it:Microbiologia]]
[[he:מיקרוביולוגיה]]
[[jv:Mikrobiologi]]
[[kn:ಸೂಕ್ಷ್ಮ ಜೀವ ವಿಜ್ಞಾನ]]
[[kk:Микробиология]]
[[ku:Hûrjînewerzanist]]
[[la:Microbiologia]]
[[lv:Mikrobioloģija]]
[[lt:Mikrobiologija]]
[[hu:Mikrobiológia]]
[[mk:Микробиологија]]
[[nl:Microbiologie]]
[[new:माइक्रोबायोलोजी]]
[[ja:微生物学]]
[[no:Mikrobiologi]]
[[nn:Mikrobiologi]]
[[nov:Mikrobiologia]]
[[oc:Microbiologia]]
[[pl:Mikrobiologia]]
[[pt:Microbiologia]]
[[ro:Microbiologie]]
[[qu:Ch'iñi kawsay yachay]]
[[ru:Микробиология]]
[[sq:Mikrobiologjia]]
[[simple:Microbiology]]
[[sk:Mikrobiológia]]
[[sl:Mikrobiologija]]
[[sr:Микробиологија]]
[[sh:Mikrobiologija]]
[[su:Mikrobiologi]]
[[fi:Mikrobiologia]]
[[sv:Mikrobiologi]]
[[tl:Mikrobiyolohiya]]
[[te:సూక్ష్మ జీవశాస్త్రం]]
[[th:จุลชีววิทยา]]
[[tr:Mikrobiyoloji]]
[[uk:Мікробіологія]]
[[ur:خرد حیاتیات]]
[[vi:Vi sinh học]]
[[wa:Bacterolodjeye]]
[[zh:微生物学]]
[[Category:2Fix]]