Micrococcus

From Wikipedia, the free encyclopedia

[[Category:]]

iMicrococcus

Micrococcus mucilaginosis

Scientific classification

Kingdom:	Bacteria
Phylum:	Actinobacteria
Class:	Actinobacteria
Subclass:	Actinobacteridae
Order:	Actinomycetales
Suborder:	Micrococcineae
Family:	Micrococcaceae
Genus:	Micrococcus Cohn 1872

Species

Micrococcus antarcticus
Micrococcus luteus
Micrococcus lylae
Micrococcus mucilaginosis
Micrococcus roseus

Micrococcus(mi’ krō kŏk’ Əs) is the type genus of bacteria in the Micrococcaceae family. Micrococcus occurs in a wide range of environments, including human skin, water, dust, and soil. Micrococci have Gram-positive spherical cells ranging from about 0.5 to perhaps 3 micrometers in diameter and are typically arranged in clusters. Micrococcus has a substantial cell wall, which may attribute as much as 50% of the cell mass. Though not a spore former, Micrococcus cells may occasionally be quite long lived. Unprotected cultures of soil micrococci have been revived after storage in a refrigerator for 10 years. Some species of Micrococcus, such as luteus (yellow) and roseus (red) produce yellow or pink colonies when grown on solid media. Isolates of M. luteus have been found to overproduce riboflavin when grown on toxic organic pollutants like pyridine. Hybridization studies indicate that species within the genus Micrococcus are not closely related, showing as little as %50 similarity. The genome of Micrococcus is rich in guanine and cytosine (GC), typically exhibiting 65 to 75% GC content. Micrococci often carry plasmids (ranging from 1 to 100MDa in size) that provide the organism with useful traits.

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 <mesophiles>, some, like Micrococcus antarcticus (found in Antarctica) are <psychrophiles>.

Micrococcus is generally thought to be a saprophytic or commensal organism, though it can be an opportunistic pathogen, particularly in hosts with compromised immune systems, such as HIV+ patients. 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).

Micrococci, like many other representatives of the Actinobacteria, can be catabolically versatile, with the ability to utilize a wide range of unusual substrates, such as pyridine, herbicides, chlorinated biphenyls, and oil. They are likely involved in detoxification or biodegradation of many other environmental pollutants. Other Micrococcus isolates produce various useful products, such as long-chain (C21-C34) aliphatic hydrocarbons for lubricating oils

Smith KJ, R Neafie, J Yeager, and HG Skelton. 1999. Micrococcus folliculitis in HIV-1 disease. British Journal of Dermatology. 141(3):558-561.

Zhuang, WQ, J-H Tay, AM Maszenan, LR Krumholz and ST-L Tay. 2003. Importance of Gram-positive naphthalene-degrading bacteria in oil-contaminated tropical marine sediments. Letters in Applied Microbiology. 36(4):251.

Doddamani, HP and HZ Ninnekar. 2001. Biodegradation of carbaryl by a Micrococcus species. Curr Microbiol.. 43(1):69-73.

Sims GK, LE Sommers, and A Konopka. 1986. Degradation of pyridine by Micrococcus luteus isolated from soil. Applied and Environmental Microbiology. 51:963-968.

Sims GK and EJ O'Loughlin. 1992. Riboflavin production during growth of Micrococcus luteus on pyridine. Applied and Environmental Microbiology 58(10):3423-3425.