View source for Biology:Microbiology

{{Short description|Study of microscopic organisms}}
[[File:Agar plate with colonies.jpg|thumb|right|An [[Organization:Agar plate|agar plate]] streaked with microorganisms]]

'''Microbiology''' ({{etymology|grc|''{{wikt-lang|grc|μῑκρος}}'' ({{grc-transl|μῑκρος}})|small||''{{wikt-lang|grc|βίος}}'' ({{grc-transl|βίος}})|life||''{{wikt-lang|grc|-λογία}}'' ({{grc-transl|-λογία}})|study of}}) is the [[Branches of science|scientific study]] of microorganisms, those being of [[Biology:Unicellular organism|unicellular]] (single-celled), [[Biology:Multicellular organism|multicellular]] (consisting of complex cells), or [[Biology:Non-cellular life|acellular]] (lacking cells).<ref>{{cite web |url=https://www.nature.com/subjects/microbiology |title=Microbiology |website=Nature |publisher=[[Company:Nature Portfolio|Nature Portfolio]] (of [[Company:Springer Nature|Springer Nature]]) |access-date=2020-02-01}}</ref><ref name=Brock>{{cite book | veditors = Madigan M, Martinko J |title=Brock Biology of Microorganisms |edition=13th |publisher=Pearson Education |year=2006 |isbn=978-0-321-73551-5 |page=1096}}</ref> Microbiology encompasses numerous sub-disciplines including [[Biology:Virology|virology]], [[Biology:Bacteriology|bacteriology]], [[Biology:Protistology|protistology]], [[Biology:Mycology|mycology]], [[Biology:Immunology|immunology]], and [[Biology:Parasitology|parasitology]].

[[Biology:Eukaryote|Eukaryotic]] microorganisms possess membrane-bound [[Biology:Organelle|organelle]]s and include [[Biology:Fungi|fungi]] and protists, whereas [[Biology:Prokaryote|prokaryotic]] organisms—all of which are microorganisms—are conventionally classified as lacking membrane-bound organelles and include [[Biology:Bacteria|Bacteria]] and [[Biology:Archaea|Archaea]].<ref>{{Cite book|title=Bergey's Manual of Systematics of Archaea and Bacteria| vauthors = Whitman WB |publisher=John Wiley and Sons|year=2015|isbn=9781118960608|doi=10.1002/9781118960608|citeseerx = 10.1.1.737.4970| veditors = Whitman WB, Rainey F, Kämpfer P, Trujillo M, Chun J, Devos P, Hedlund B, Dedysh S }}</ref><ref>{{cite journal | vauthors = Pace NR | title = Time for a change | language = En | journal = Nature | volume = 441 | issue = 7091 | pages = 289 | date = May 2006 | pmid = 16710401 | doi = 10.1038/441289a | s2cid = 4431143 | bibcode = 2006Natur.441..289P | doi-access = free }}</ref> [[Microbiologist]]s traditionally relied on culture, staining, and [[Biology:Microscopy|microscopy]] for the isolation and identification of microorganisms. However, less than 1% of the microorganisms present in common environments can be cultured in isolation using current means.<ref name="Amann1995">{{cite journal |vauthors=Amann RI, Ludwig W, Schleifer KH | title = Phylogenetic identification and in situ detection of individual microbial cells without cultivation | journal = Microbiological Reviews | volume = 59 | issue = 1 | pages = 143–169 | date = March 1995 | pmid = 7535888 | pmc = 239358 | doi = 10.1128/mr.59.1.143-169.1995 }}</ref> With the emergence of [[Engineering:Biotechnology|biotechnology]], Microbiologists currently rely on [[Biology:Molecular biology|molecular biology]] tools such as DNA sequence-based identification, for example, the [[Biology:16S ribosomal RNA|16S rRNA]] gene sequence used for bacterial identification.

[[Biology:Virus|Virus]]es have been variably classified as organisms,<ref>{{cite web | vauthors = Rice G | title = Are Viruses Alive? | url = http://serc.carleton.edu/microbelife/yellowstone/viruslive.html | date = 2007-03-27 |access-date = 2007-07-23}}</ref> as they have been considered either as very simple microorganisms or very complex molecules. Prions, never considered as microorganisms, have been investigated by virologists, however, as the clinical effects traced to them were originally presumed due to chronic viral infections, virologists took a search—discovering "infectious proteins".

The existence of microorganisms was predicted many centuries before they were first observed, for example by the [[Philosophy:Jainism|Jains]] in India and by Marcus Terentius Varro in ancient Rome. The first recorded microscope observation was of the fruiting bodies of moulds, by Robert Hooke in 1666, but the Jesuit priest [[Biography:Athanasius Kircher|Athanasius Kircher]] was likely the first to see microbes, which he mentioned observing in milk and putrid material in 1658. [[Biography:Antonie van Leeuwenhoek|Antonie van Leeuwenhoek]] is considered a father of microbiology as he observed and experimented with microscopic organisms in the 1670s, using simple [[Engineering:Microscope|microscope]]s of his design. Scientific microbiology developed in the 19th century through the work of Louis Pasteur and in medical microbiology [[Biography:Robert Koch|Robert Koch]].

==History==
{{More information|List of microbiologists#Proto-microbiologists|l1=Proto-microbiologists|History of microscopy|Microscopic discovery of bacteria}}

[[File:Avicenna TajikistanP17-20Somoni-1999 (cropped).png|left|thumb|upright|Avicenna postulated the existence of microorganisms.]]
The existence of microorganisms was hypothesized for many centuries before their actual discovery. The existence of unseen microbiological life was postulated by [[Philosophy:Jainism|Jainism]] which is based on Mahavira's teachings as early as 6th century BCE (599 BC - 527 BC).<ref name = "Dundas_2002">{{cite book | vauthors = Dundas P | veditors =  Hinnels J | title = The Jain | publisher =Routledge | year = 2002 | location = London | isbn =978-0-415-26606-2 }}</ref>{{rp|24}} Paul Dundas notes that Mahavira asserted the existence of unseen microbiological creatures living in earth, water, air and fire.<ref name = "Dundas_2002" />{{rp|88}} Jain scriptures describe nigodas which are sub-microscopic creatures living in large clusters and having a very short life, said to pervade every part of the universe, even in tissues of plants and flesh of animals.<ref>{{cite book | vauthors = Jaini P | title =The Jaina Path of Purification | publisher =Motilal Banarsidass | year =1998 | location =New Delhi | isbn =978-81-208-1578-0 |page= 109}}</ref> The [[History: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 thereby cause serious diseases."<ref>{{cite book | vauthors = Varro MT |  title = The three books of M. Terentius Varro concerning agriculture. | publisher = At the University Press | location = Charing Cross, London | date = 1800 | volume = 1 | page = xii }} <!-- ''Varro on Agriculture'' 1, xii Loeb. --></ref>

Persian scientists hypothesized the existence of microorganisms, such as [[Biography:Avicenna|Avicenna]] in his book ''The Canon of Medicine'', [[Biography:Ibn Zuhr|Ibn Zuhr]] (also known as Avenzoar) who discovered [[Medicine:Scabies|scabies]] mites, and [[Biography:Muhammad ibn Zakariya al-Razi|Al-Razi]] who gave the earliest known description of [[Medicine:Smallpox|smallpox]] in his book ''The Virtuous Life'' (al-Hawi).<ref>{{cite web|title=فى الحضارة الإسلامية - ديوان العرب|trans-title=Microbiology in Islam|url=http://www.diwanalarab.com/spip.php?article34512|work=Diwanalarab.com|language=ar|access-date=14 April 2017}}</ref> The tenth-century Taoist {{em|Baoshengjing}} describes "countless  micro  organic  worms" which resemble vegetable seeds, which prompted Dutch sinologist Kristofer Schipper to claim that "the  existence  of  harmful  bacteria was  known  to  the Chinese  of  the  time."<ref name="Huang 2011 pp. 32–62">{{cite journal | last=Huang | first=Shih-Shan Susan | title=Daoist Imagery of Body and Cosmos, Part 2: Body Worms and Internal Alchemy | journal=Journal of Daoist Studies | volume=4 | issue=1 | date=2011 | issn=1941-5524 | doi=10.1353/dao.2011.0001 | pages=32–62}}</ref>

In 1546, Girolamo Fracastoro proposed that [[Medicine:Epidemic|epidemic]] diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or vehicle transmission.<ref>{{cite book | vauthors = Fracastoro G | orig-date = 1546 | title = De Contagione et Contagiosis Morbis | trans-title = On Contagion and Contagious Diseases | language  = Latin | translator = Wright WC | translator-link = Wilmer Cave Wright | date = 1930 | location = New York | publisher = G.P. Putnam }}</ref>

[[File:Anthonie van Leeuwenhoek (1632-1723). Natuurkundige te Delft Rijksmuseum SK-A-957.jpeg|thumb|upright|Antonie van Leeuwenhoek (1632–1723)]]
[[File:Van Leeuwenhoek's microscopes by Henry Baker.jpg|thumb|alt=Schematic drawings|Van Leeuwenhoek's microscopes by Henry Baker<ref name="ChungLiu">{{cite book | vauthors = Chung KT, Liu JK | title = Pioneers in Microbiology: The Human Side of Science | publisher = World Scientific Publishing | date = 2017 | isbn = 978-9813202948 | quote = We may fairly call Leeuwenhoek "The first microbiologist" because he was the first individual to actually culture, see, and describe a large array of microbial life. He actually measured the multiplication of the bugs. What is more amazing is that he published his discoveries. }}</ref>]]
[[File:Martinus Willem Beijerinck in his laboratory.jpg|thumb|upright|Martinus Beijerinck is often considered as a founder of virology.]]

In 1676, [[Biography:Antonie van Leeuwenhoek|Antonie van Leeuwenhoek]], who lived most of his life in Delft, Netherlands, observed [[Biology:Bacteria|bacteria]] and other microorganisms using a [[Biography:Antonie van Leeuwenhoek#Techniques and discoveries|single-lens microscope of his own design]].<ref name="NickLane_RS">{{cite journal | vauthors = Lane N | title = The unseen world: reflections on Leeuwenhoek (1677) 'Concerning little animals' | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 370 | issue = 1666 | page = 20140344 | date = April 2015 | pmid = 25750239 | pmc = 4360124 | doi = 10.1098/rstb.2014.0344 | author-link = Nick Lane }}</ref><ref name=Brock /> He is considered a father of microbiology as he used simple single-lensed [[Engineering:Microscope|microscope]]s of his own design.<ref name="NickLane_RS"/> While Van Leeuwenhoek is often cited as the first to observe microbes, Robert Hooke made his first recorded microscopic observation, of the fruiting bodies of moulds, in 1665.<ref>{{cite journal | vauthors = Gest H | title = The remarkable vision of Robert Hooke (1635-1703): first observer of the microbial world | journal = Perspectives in Biology and Medicine | volume = 48 | issue = 2 | pages = 266–272 | year = 2005 | pmid = 15834198 | doi = 10.1353/pbm.2005.0053 | s2cid = 23998841 }}</ref> It has, however, been suggested that a Jesuit priest called [[Biography:Athanasius Kircher|Athanasius Kircher]] was the first to observe microorganisms.<ref name=pmid12964250>{{cite book | vauthors = Wainwright M |title=An Alternative View of the Early History of Microbiology |volume=52 |pages=333–55 |year=2003 |pmid=12964250 |doi=10.1016/S0065-2164(03)01013-X |series=Advances in Applied Microbiology |isbn=978-0-12-002654-8 }}</ref>

Kircher was among the first to design magic lanterns for projection purposes, and so he was well acquainted with the properties of lenses.<ref name=pmid12964250/> He wrote "Concerning the wonderful structure of things in nature, investigated by Microscope" in 1646, stating "who would believe that vinegar and milk abound with an innumerable multitude of worms." He also noted that putrid material is full of innumerable creeping animalcules. He published his ''Scrutinium Pestis'' (Examination of the Plague) in 1658, stating correctly that the disease was caused by microbes, though what he saw was most likely red or white blood cells rather than the plague agent itself.<ref name=pmid12964250/>

==The birth of bacteriology==

[[File:Albert Edelfelt - Louis Pasteur - 1885.jpg|thumb|left|upright|Innovative laboratory glassware and experimental methods developed by Louis Pasteur and other biologists contributed to the young field of bacteriology in the late 19th century.]]

The field of [[Biology:Bacteriology|bacteriology]] (later a subdiscipline of microbiology) was founded in the 19th century by Ferdinand Cohn, a botanist whose studies on [[Biology:Algae|algae]] and [[Biology:Phototroph|photosynthetic bacteria]] led him to describe several bacteria including ''[[Biology:Bacillus|Bacillus]]'' and ''[[Biology:Beggiatoa|Beggiatoa]]''. Cohn was also the first to formulate a scheme for the taxonomic classification of bacteria, and to discover [[Biology:Endospore|endospore]]s.<ref>{{cite journal | vauthors = Drews G |title=Ferdinand Cohn, among the Founder of Microbiology |journal=ASM News |volume=65 |issue=8 |page=547 |year=1999}}</ref> Louis Pasteur and [[Biography:Robert Koch|Robert Koch]] were contemporaries of Cohn, and are often considered to be the fathers of modern microbiology<ref name=pmid12964250/> and [[Medicine:Medical microbiology|medical microbiology]], respectively.<ref name=Sherris>{{cite book | veditors = Ryan KJ, Ray CG | title=Sherris Medical Microbiology | edition=4th | publisher=McGraw Hill | year=2004 | isbn=978-0-8385-8529-0 }}</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 | vauthors = Bordenave G | title = Louis Pasteur (1822-1895) | journal = Microbes and Infection | volume = 5 | issue = 6 | pages = 553–560 | date = May 2003 | pmid = 12758285 | doi = 10.1016/S1286-4579(03)00075-3 }}</ref> One of his students, Adrien Certes, is considered the founder of marine microbiology.<ref>{{cite journal | vauthors = Adler A, Dücker E | title = When Pasteurian Science Went to Sea: The Birth of Marine Microbiology | journal = Journal of the History of Biology | volume = 51 | issue = 1 | pages = 107–133 | date = March 2018 | pmid = 28382585 | doi = 10.1007/s10739-017-9477-8 | s2cid = 22211340 }}</ref> Pasteur also designed methods for food preservation ([[Chemistry:Pasteurization|pasteurization]]) and vaccines against several diseases such as [[Medicine:Anthrax|anthrax]], fowl cholera and [[Medicine:Rabies|rabies]].<ref name=Brock /> Koch is best known for his contributions to the [[Biology:Germ theory of disease|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 [[Medicine:Koch's postulates|Koch's postulates]]. Koch was one of the first scientists to focus on the isolation of [[Biology:Bacteria|bacteria]] in pure culture resulting in his description of several novel bacteria including ''[[Biology:Mycobacterium tuberculosis|Mycobacterium tuberculosis]]'', the causative agent of [[Medicine:Tuberculosis|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 [[Biography:Martinus Beijerinck|Martinus Beijerinck]] and Sergei Winogradsky that the true breadth of microbiology was revealed.<ref name=Brock /> Beijerinck made two major contributions to microbiology: the discovery of [[Biology:Virus|virus]]es and the development of [[Biology:Enrichment culture|enrichment culture]]<!-- should this be Growth medium or [[Biology:Microbiological culture|Microbiological culture]] ? --> techniques.<ref>{{cite web |  vauthors = Johnson J | title=Martinus Willem Beijerinck | work=APSnet| publisher=American Phytopathological Society | url=http://apsnet.org/education/feature/TMV/intro.html | archive-url=https://web.archive.org/web/20100620173433/http://apsnet.org/education/feature/TMV/intro.html | archive-date=2010-06-20 | year=2001 |orig-year=1998 | access-date=May 2, 2010}} Retrieved from Internet Archive January 12, 2014.</ref> While his work on the [[Biology:Tobacco mosaic virus|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 |vauthors=Paustian T, Roberts G | chapter=Beijerinck and Winogradsky Initiate the Field of Environmental Microbiology | title=Through the Microscope: A Look at All Things Small | at=§&nbsp;1–14 | edition=3rd | year=2009 | publisher=Textbook Consortia | chapter-url=http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=32}}</ref> He was responsible for the first isolation and description of both [[Biology:Nitrifying bacteria|nitrifying]] and nitrogen-fixing bacteria.<ref name=Brock /> French-Canadian microbiologist Felix d'Herelle co-discovered [[Biology:Bacteriophage|bacteriophage]]s in 1917 and was one of the earliest applied microbiologists.<ref name =Keen>{{cite journal | vauthors = Keen EC | title = Felix d'Herelle and our microbial future | journal = Future Microbiology | volume = 7 | issue = 12 | pages = 1337–1339 | date = December 2012 | pmid = 23231482 | doi = 10.2217/fmb.12.115 }}</ref>

Joseph Lister was the first to use [[Chemistry:Phenol|phenol]] disinfectant on the open wounds of patients.<ref>{{cite journal | vauthors = Lister BJ | title = The classic: On the antiseptic principle in the practice of surgery. 1867 | journal = Clinical Orthopaedics and Related Research | volume = 468 | issue = 8 | pages = 2012–2016 | date = August 2010 | pmid = 20361283 | pmc = 2895849 | doi = 10.1007/s11999-010-1320-x }}</ref>

==Branches==
[[File:LUA, Faculty of Food Technology Food microbiology laboratory.jpg|thumb|A university food microbiology laboratory]]
{{main|Biology:Branches of microbiology}}

The [[Biology:Branches of microbiology|branches of microbiology]] can be classified into applied sciences, or divided according to taxonomy, as is the case with [[Biology:Bacteriology|bacteriology]], [[Biology:Mycology|mycology]], [[Biology:Protozoology|protozoology]], [[Biology:Virology|virology]], [[Biology:Phycology|phycology]], and [[Earth:Microbial ecology|microbial ecology]]. There is considerable overlap between the specific branches of microbiology with each other and with other disciplines, and certain aspects of these branches can extend beyond the traditional scope of microbiology<ref>{{Cite news |url=http://www.generalmicroscience.com/microbiology/branches-of-microbiology/ |title=Branches of Microbiology |date=2017-01-13 |work=General MicroScience |access-date=2017-12-10}}</ref><ref>{{cite book |title=Brock Biology of Microorganisms |isbn=978-0321897398 |edition=14th| vauthors = Madigan MT, Martinko JM, Bender KS, Buckley DH, Stahl DA |year=2015 |publisher=Pearson }}</ref> A pure research branch of microbiology is termed [[Biology:Cellular microbiology|cellular microbiology]].

==Applications==

While some people have fear of microbes due to the association of some microbes with various human diseases, many microbes are also responsible for numerous beneficial processes such as [[Biology:Industrial fermentation|industrial fermentation]] (e.g. the production of [[Chemistry:Ethanol|alcohol]], [[Chemistry:Vinegar|vinegar]] and dairy products), [[Chemistry:Antibiotic|antibiotic]] production and act as molecular vehicles to transfer DNA to complex organisms such as plants and animals. Scientists have also exploited their knowledge of microbes to produce biotechnologically important [[Biology:Enzyme|enzyme]]s such as [[Biology:Taq polymerase|Taq polymerase]],<ref>{{Cite book| vauthors = Gelfand DH |chapter=Taq DNA Polymerase|date=1989|work=PCR Technology: Principles and Applications for DNA Amplification|pages=17–22| veditors = Erlich HA |publisher=Palgrave Macmillan UK|language=en|doi=10.1007/978-1-349-20235-5_2|isbn=978-1-349-20235-5|title=PCR Technology|s2cid=100860897 }}</ref> [[Biology:Reporter gene|reporter gene]]s for use in other genetic systems and novel molecular biology techniques such as the [[Biology:Two-hybrid screening|yeast two-hybrid system]].<ref>{{Cite journal |last=Uetz |first=Peter |date=December 2012 |title=Editorial for "The Yeast two-hybrid system" |url=https://pubmed.ncbi.nlm.nih.gov/23317557/ |journal=Methods |volume=58 |issue=4 |pages=315–316 |doi=10.1016/j.ymeth.2013.01.001 |issn=1095-9130 |pmid=23317557}}</ref>

Bacteria can be used for the industrial production of [[Chemistry:Amino acid|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 | veditors = Burkovski A | title = Corynebacteria: Genomics and Molecular Biology | publisher = Caister Academic Press | year = 2008 | url=http://www.horizonpress.com/cory | isbn =978-1-904455-30-1 | access-date = 2016-03-25}}</ref> Since some bacteria have the ability to synthesize antibiotics, they are used for medicinal purposes, such as [[Biology:Streptomyces|Streptomyces]] to make aminoglycoside antibiotics.<ref name= "Puglisi, Joseph D.">{{cite journal | vauthors = Fourmy D, Recht MI, Blanchard SC, Puglisi JD | title = Structure of the A site of Escherichia coli 16S ribosomal RNA complexed with an aminoglycoside antibiotic | journal = Science | volume = 274 | issue = 5291 | pages = 1367–1371 | date = November 1996 | pmid = 8910275 | doi = 10.1126/science.274.5291.1367 | s2cid = 21602792 | bibcode = 1996Sci...274.1367F }}</ref>

[[File:Cuves de fermentations.jpg|thumb|upright|left|Fermenting tanks with [[Biology:Yeast|yeast]] being used to brew beer ]]

A variety of [[Biology:Biopolymer|biopolymer]]s, such as [[Chemistry:Polysaccharide|polysaccharide]]s, [[Chemistry:Polyester|polyester]]s, and [[Chemistry:Polyamide|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 [[Engineering:Tissue engineering|tissue engineering]] and drug delivery. Microorganisms are for example used for the biosynthesis of xanthan, alginate, [[Chemistry:Cellulose|cellulose]], [[Chemistry:Cyanophycin|cyanophycin]], poly(gamma-glutamic acid), [[Chemistry:Levan polysaccharide|levan]], [[Chemistry:Hyaluronic acid|hyaluronic acid]], organic acids, [[Chemistry:Oligosaccharide|oligosaccharide]]s [[Chemistry:Polysaccharide|polysaccharide]] and polyhydroxyalkanoates.<ref name= RehmBHA>{{cite book | veditors = Rehm BH | title = Microbial Production of Biopolymers and Polymer Precursors: Applications and Perspectives | publisher = Caister Academic Press | year = 2008 | url=http://www.horizonpress.com/biopolymers | isbn =978-1-904455-36-3 | access-date = 2016-03-25}}</ref>

Microorganisms are beneficial for [[Earth:Microbial biodegradation|microbial biodegradation]] or [[Earth:Bioremediation|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 [[Earth:Microbial biodegradation|microbial biodegradation]] is to use a mixture of bacterial and fungal species and strains, each specific to the biodegradation of one or more types of contaminants.<ref name=Diaz>{{cite book | veditors = Diaz E | title = Microbial Biodegradation: Genomics and Molecular Biology | edition = 1st | publisher = Caister Academic Press | year = 2008 | url = https://archive.org/details/microbialbiodegr0000unse | isbn = 978-1-904455-17-2 | access-date = 2016-03-25 | url-access = registration }}</ref>

[[Biology:Mutualism|Symbiotic]] microbial communities confer benefits to their human and animal hosts health including aiding digestion, producing beneficial vitamins and amino acids, and suppressing pathogenic microbes. Some benefit may be conferred by eating fermented foods, probiotics (bacteria potentially beneficial to the digestive system) or prebiotics (substances consumed to promote the growth of probiotic microorganisms).<ref>{{cite journal | vauthors = Macfarlane GT, Cummings JH | title = Probiotics and prebiotics: can regulating the activities of intestinal bacteria benefit health? | journal = BMJ | volume = 318 | issue = 7189 | pages = 999–1003 | date = April 1999 | pmid = 10195977 | pmc = 1115424 | doi = 10.1136/bmj.318.7189.999 }}</ref><ref name=Tannockpro3>{{cite book | veditors = Tannock GW | title = Probiotics and Prebiotics: Scientific Aspects | publisher = Caister Academic Press | year = 2005 | url=http://www.horizonpress.com/pro3 | isbn =978-1-904455-01-1 | access-date = 2016-03-25}}</ref> The ways the microbiome influences human and animal health, as well as methods to influence the microbiome are active areas of research.<ref>{{cite magazine|url=http://www.scientificamerican.com/article.cfm?id=strange-but-true-humans-carry-more-bacterial-cells-than-human-ones|title=Humans Carry More Bacterial Cells than Human Ones| vauthors = Wenner M |magazine= Scientific American|date=30 November 2007|access-date=14 April 2017}}</ref>

Research has suggested that microorganisms could be useful in the treatment of [[Medicine:Cancer|cancer]]. Various strains of non-pathogenic [[Biology:Clostridium|clostridia]] can infiltrate and replicate within solid [[Medicine:Tumors|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 | vauthors = Mengesha A, Dubois L, Paesmans K, Wouters B, Lambin P, Theys J |year=2009|chapter=Clostridia in Anti-tumor Therapy | veditors = Brüggemann H, Gottschalk G |title=Clostridia: Molecular Biology in the Post-genomic Era|publisher=Caister Academic Press|isbn = 978-1-904455-38-7 }}</ref>

Some bacteria are used to study fundamental mechanisms. An example of model bacteria used to study [[Biology:Motility|motility]]<ref>{{cite journal | vauthors = Zusman DR, Scott AE, Yang Z, Kirby JR | title = Chemosensory pathways, motility and development in Myxococcus xanthus | journal = Nature Reviews. Microbiology | volume = 5 | issue = 11 | pages = 862–872 | date = November 2007 | pmid = 17922045 | doi = 10.1038/nrmicro1770 | s2cid = 2340386 }}</ref> or the production of polysaccharides and development is ''[[Biology:Myxococcus xanthus|Myxococcus xanthus]]''.<ref>{{cite journal | vauthors = Islam ST, Vergara Alvarez I, Saïdi F, Guiseppi A, Vinogradov E, Sharma G, Espinosa L, Morrone C, Brasseur G, Guillemot JF, Benarouche A, Bridot JL, Ravicoularamin G, Cagna A, Gauthier C, Singer M, Fierobe HP, Mignot T, Mauriello EM | display-authors = 6 | title = Modulation of bacterial multicellularity via spatio-specific polysaccharide secretion | journal = PLOS Biology | volume = 18 | issue = 6 | pages = e3000728 | date = June 2020 | pmid = 32516311 | pmc = 7310880 | doi = 10.1371/journal.pbio.3000728 | doi-access = free }}</ref>
<!-- These traits allowed Joshua and Esther Lederberg to devise an elegant experiment in 1951 demonstrating that [[Biology:Adaptive mutation|adaptive mutation]]s arise from preadaptation rather than directed mutation. For this purpose, they invented [[Biology:Replica plating|replica plating]], which allowed them to transfer numerous [[Biology:Colony|bacterial colonies]] from their specific locations on one [[Biology:Agar|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 [[Biology:Bacteriophage|bacteriophage]]. 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.-->

== See also ==
{{colbegin}}
* [[Biology:Biosafety|Biosafety]]
* ''[[Biology:Microbes and Man|Microbes and Man]]''
;Professional organizations
* [[Organization:American Society for Microbiology|American Society for Microbiology]]
* [[Organization:Federation of European Microbiological Societies|Federation of European Microbiological Societies]]
* [[Organization:Society for Applied Microbiology|Society for Applied Microbiology]]
* Society for General Microbiology
;Journals
* [[Biology:Critical Reviews in Microbiology|Critical Reviews in Microbiology]]
* [[Biology:International Journal of Systematic and Evolutionary Microbiology|International Journal of Systematic and Evolutionary Microbiology]]
* [[Biology:Journal of Bacteriology|Journal of Bacteriology]]
* [[Biology:Nature Reviews Microbiology|Nature Reviews Microbiology]]
{{colend}}

== References ==
{{Reflist|30em}}

== Further reading ==
{{refbegin}}
* {{cite journal | vauthors = Kreft JU, Plugge CM, Grimm V, Prats C, Leveau JH, Banitz T, Baines S, Clark J, Ros A, Klapper I, Topping CJ, Field AJ, Schuler A, Litchman E, Hellweger FL | display-authors = 6 | title = Mighty small: Observing and modeling individual microbes becomes big science | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 110 | issue = 45 | pages = 18027–18028 | date = November 2013 | pmid = 24194530 | pmc = 3831448 | doi = 10.1073/pnas.1317472110 | bibcode = 2013PNAS..11018027K | doi-access = free }}
* {{Cite book| vauthors = Madigan MT, Martinko JM, Bender KS, Buckley DH, Stahl DA |url= https://books.google.com/books?id=eBnLCQAAQBAJ |title=Brock Biology of Microorganisms, Global Edition |date=2015-06-05|publisher=Pearson Education Limited|isbn=978-1-292-06831-2}}
{{refend}}

== External links ==
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* nature.com [http://www.nature.com/subjects/microbiology Latest Research, reviews and news on microbiology]
* [http://www.microbes.info/ Microbes.info] is a microbiology information portal containing a vast collection of resources including articles, news, frequently asked questions, and links pertaining to the field of microbiology.
* [http://www.microbiologybook.org/book/welcome.htm Immunology, Bacteriology, Virology, Parasitology, Mycology and Infectious Disease]
* [http://arjournals.annualreviews.org/loi/micro/ Annual Review of Microbiology] {{Webarchive|url=https://web.archive.org/web/20090120021246/http://arjournals.annualreviews.org/loi/micro |date=2009-01-20 }}

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[[Category:Microbiology| ]]
[[Category:Branches of biology]]
[[Category:Microscopy]]

{{Sourceattribution|Microbiology}}