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'{{italictitle}} {{Taxobox | color = lightgrey | name = ''Micrococcus'' | image = Micrococcus_mucilaginosis_01.png | image_width = 240px | image_caption = ''Micrococcus mucilaginosis'' | regnum = [[Bacterium|Bacteria]] | phylum = [[Actinobacteria]] | classis = [[Actinobacteria (class)|Actinobacteria]] | subclassis = [[Actinobacteridae]] | ordo = [[Actinomycetales]] | subordo = [[Micrococcineae]] | familia = [[Micrococcaceae]] | genus = '''''Micrococcus''''' | genus_authority = Cohn 1872 | subdivision_ranks = Species | subdivision = ''[[Micrococcus antarcticus]]''<br/> ''[[Micrococcus flavus]]''<br/> ''[[Micrococcus luteus]]''<br/> ''[[Micrococcus lylae]]''<br/> ''[[Micrococcus mucilaginosis]]''<br/> ''[[Micrococcus roseus]]'' }} '''''Micrococcus''''' (mi’ krō kŏk’ Əs) is a [[genus]] of [[bacteria]] in the [[Micrococcaceae]] [[family (biology)|family]]. ''Micrococcus'' occurs in a wide range of environments, including water, dust, and soil. Micrococci have [[Gram-positive]] spherical cells ranging from about 0.5 to 3 micrometers in diameter and are typically appear in tetrads. ''Micrococcus'' has a substantial [[cell wall]], which may comprise as much as 50% of the cell mass. The genome of ''Micrococcus'' is rich in [[guanine]] and [[cytosine]] (GC), typically exhibiting 65 to 75% [[GC-content]]. Micrococci often carry [[plasmid]]s (ranging from 1 to 100MDa in size) that provide the organism with useful traits. ==Species== Some species of ''Micrococcus'', such as ''M. luteus'' (yellow) and ''M. roseus'' (red) produce yellow or pink colonies when grown on mannitol salt agar. Isolates of ''M. luteus'' have been found to overproduce [[riboflavin]] when grown on toxic organic pollutants like pyridine.<ref>{{cite journal |author=Sims GK, Sommers LE, Konopka A | title=Degradation of Pyridine by Micrococcus luteus Isolated from Soil |journal=Appl Environ Microbiol |volume=51 |issue=5 |pages=963–968 |year=1986 |pmid=16347070 |pmc=238995}}</ref> [[Hybrid (biology)|Hybridization]] studies indicate that species within the genus ''Micrococcus'' are not closely related, showing as little as 50% [[Homology (biology)#Homology of sequences in genetics|sequence homology]]. This suggests that some ''Micrococcus'' species may, on the basis of [[ribosomal RNA]] analysis, eventually be re-classified into other microbial genera. ==Environmental== Micrococci have been isolated from human skin, animal and dairy products, and beer. They are found in many other places in the environment, including water, dust, and soil. ''M. luteus'' on human skin transforms compounds in sweat into compounds with an [[unpleasant odor]]. Micrococci can grow well in environments with little water or high salt concentrations. Most are [[mesophile]]s; some, like ''Micrococcus antarcticus'' (found in Antarctica) are [[psychrophile]]s. Though not a [[spore]] former, ''Micrococcus'' cells can survive for an extended period of time: unprotected cultures of soil micrococci have been revived after storage in a refrigerator for 10 years.{{Fact|date=February 2007}} Recent work by Greenblat et al. demonstrate that ''Micrococcus luteus'' has survived for at least 34,000 to 170,000 years on the basis of 16S rRNA analysis, and possibly much longer.<ref>{{cite journal | author= Greenblat, C.L., Baum, J., Klein, B.Y., Nachshon, S., Koltunov, V., Cano, R.J., | title = Micrococcus luteus – Survival in Amber | journal = Microbial Ecology | volume = 48 | pages = 120–127 | year = 2004 | pmid=15164240 | doi = 10.1007/s00248-003-2016-5 | issue= 1}}</ref> ==Pathogenesis== ''Micrococcus'' is generally thought to be a saprotrophic or [[commensal organism]], though it can be an [[opportunistic pathogen]], particularly in hosts with [[Immunodeficiency|compromised immune systems]], such as [[HIV]] patients.<ref name=Smith_1999>{{cite journal |author=Smith K, Neafie R, Yeager J, Skelton H |title=Micrococcus folliculitis in HIV-1 disease |journal=Br J Dermatol |volume=141 |issue=3 |pages=558–61 |year=1999 |pmid=10583069 |doi=10.1046/j.1365-2133.1999.03060.x}}</ref> It can be difficult to identify ''Micrococcus'' as the cause of an infection, since the organism is a normally present in skin microflora, and the genus is seldom linked to disease. In rare cases, death of immunocompromised patients has occurred from pulmonary infections caused by ''Micrococcus''. Micrococci may be involved in other infections, including recurrent bacteremia, septic shock, septic arthritis, endocarditis, meningitis, and cavitating pneumonia (immunosuppressed patients). ==Industrial uses== Micrococci, like many other representatives of the Actinobacteria, can be [[Catabolism|catabolically]] versatile, with the ability to utilize a wide range of unusual substrates, such as [[pyridine]], [[herbicide]]s, [[Polychlorinated biphenyls|chlorinated biphenyls]], and [[Petroleum|oil]].<ref name=Doddamani_2001>{{cite journal |author=Doddamani H, Ninnekar H |title=Biodegradation of carbaryl by a Micrococcus species |journal=Curr Microbiol |volume=43 |issue=1 |pages=69–73 |year=2001 |pmid=11375667 |doi=10.1007/s002840010262}}</ref><ref>{{cite journal |author=Sims GK, O'loughlin EJ |title=Riboflavin Production during Growth of Micrococcus luteus on Pyridine |journal=Appl Environ Microbiol |volume=58 |issue=10 |pages=3423–3425 |year=1992 |pmid=16348793 |pmc=183117}}</ref> They are likely involved in detoxification or biodegradation of many other environmental pollutants.<ref name=Zhuang_2003>{{cite journal |author=Zhuang W, Tay J, Maszenan A, Krumholz L, Tay S |title=Importance of Gram-positive naphthalene-degrading bacteria in oil-contaminated tropical marine sediments |journal=Lett Appl Microbiol |volume=36 |issue=4 |pages=251–7 |year=2003 |pmid=12641721}}</ref> Other ''Micrococcus'' isolates produce various useful products, such as long-chain (C21-C34) aliphatic hydrocarbons for lubricating oils. ==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> and <reference /> tags ----------------------------------------------------------- --> {{reflist}} [http://microbewiki.kenyon.edu/index.php/Micrococcus Microbewiki] at [[Kenyon College]] [[Category:Micrococcineae]] [[ar:مكيرة]] [[cs:Micrococcus]] [[es:Micrococcus]] [[eu:Micrococcus]] [[fr:Micrococcus]] [[ja:マイクロコッカス属]] [[pt:Micrococcus]]'