Ultramicrobacteria

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Ultramicrobacteria are bacteria that are considerably smaller than typical bacterial cells and are 0.3 to 0.2 micrometres in diameter. This term was first used in 1981, to refer to cocci in seawater that were less than 0.3 μm in diameter.[1] These cells have also been recovered from soil and appeared to be a mixture of Gram-positive and negative species.[2] Many, if not all, of these small bacteria are dormant forms of larger cells that allow survival under starvation conditions.[3] In this process, cells downregulate their metabolism, stop growing and stabilize their DNA, creating dormant non-growing cells that can remain viable for many years.[4] These starvation forms may be the most common type of ultramicrobacteria in seawater.[5]

These small living bacterial cells are distinct from the purported "nanobacteria" or "calcifying nanoparticles", which were proposed to be living organisms that were 0.1 μm in diameter.[6] These structures are now thought to be non-living,[7] and are probably precipitated particles of inorganic material.[8][9]

See also[edit]

References[edit]

  1. ^ Torrella F, Morita RY (1 February 1981). "Microcultural Study of Bacterial Size Changes and Microcolony and Ultramicrocolony Formation by Heterotrophic Bacteria in Seawater". Appl. Environ. Microbiol. 41 (2): 518–527. PMC 243725. PMID 16345721. 
  2. ^ Iizuka T, Yamanaka S, Nishiyama T, Hiraishi A (February 1998). "Isolation and phylogenetic analysis of aerobic copiotrophic ultramicrobacteria from urban soil". J. Gen. Appl. Microbiol. (– Scholar search) 44 (1): 75–84. doi:10.2323/jgam.44.75. PMID 12501296. 
  3. ^ Velimirov, B. (2001). "Nanobacteria, Ultramicrobacteria and Starvation Forms: A Search for the Smallest Metabolizing Bacterium". Microbes and Environments 16 (2): 67–77. doi:10.1264/jsme2.2001.67. Retrieved 2008-06-23. 
  4. ^ Costerton JW, Lewandowski Z, Caldwell DE, Korber DR, Lappin-Scott HM (1995). "Microbial biofilms". Annu. Rev. Microbiol. 49: 711–45. doi:10.1146/annurev.mi.49.100195.003431. PMID 8561477. 
  5. ^ Haller CM, Rölleke S, Vybiral D, Witte A, Velimirov B (February 2000). "Investigation of 0.2 µm filterable bacteria from the Western Mediterranean Sea using a molecular approach: dominance of potential starvation forms". FEMS Microbiol. Ecol. 31 (2): 153–161. PMID 10640668. 
  6. ^ Urbano P, Urbano F (May 2007). "Nanobacteria: Facts or Fancies?". PLoS Pathog. 3 (5): e55. doi:10.1371/journal.ppat.0030055. PMC 1876495. PMID 17530922. 
  7. ^ Kajander EO (June 2006). "Nanobacteria--propagating calcifying nanoparticles". Lett. Appl. Microbiol. 42 (6): 549–52. doi:10.1111/j.1472-765X.2006.01945.x. PMID 16706890. 
  8. ^ Raoult D, Drancourt M, Azza S, et al. (February 2008). "Nanobacteria Are Mineralo Fetuin Complexes". PLoS Pathog. 4 (2): e41. doi:10.1371/journal.ppat.0040041. PMC 2242841. PMID 18282102. 
  9. ^ Martel J, Young JD (April 2008). "Purported nanobacteria in human blood as calcium carbonate nanoparticles". Proc. Natl. Acad. Sci. U.S.A. 105 (14): 5549–54. doi:10.1073/pnas.0711744105. PMC 2291092. PMID 18385376.