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bacteria that form colonies in self-produced slime; inhabit moist soils or decaying plant matter or animal waste (同)myxobacterium, myxobacter, gliding_bacteria, slime bacteria

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/01/03 18:51:33」(JST)

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Not to be confused with slime mold.

The myxobacteria ("slime bacteria") are a group of bacteria that predominantly live in the soil and feed on insoluble organic substances. The myxobacteria have very large genomes, relative to other bacteria, e.g. 9–10 million nucleotides. Sorangium cellulosum has the largest (as of 2008) bacterial genome, at 13.0 million nucleotides.^[1] Myxobacteria are included among the delta group of proteobacteria, a large taxon of Gram-negative forms.

Myxobacteria can move actively by gliding. They typically travel in swarms (also known as wolf packs), containing many cells kept together by intercellular molecular signals. Individuals benefit from aggregation as it allows accumulation of extracellular enzymes which are used to digest food, this in turn increases feeding efficiency. Myxobacteria produce a number of biomedically and industrially useful chemicals, such as antibiotics, and export those chemicals outside of the cell.^[2]

Life cycle[edit]

When nutrients are scarce, myxobacterial cells aggregate into fruiting bodies (not to be confused with those in fungi), a process long-thought to be mediated by chemotaxis but now considered to be a function of a form of contact-mediated signaling.^[3]^[4] These fruiting bodies can take different shapes and colors, depending on the species. Within the fruiting bodies, cells begin as rod-shaped vegetative cells, and develop into rounded myxospores with thick cell walls. These myxospores, analogous to spores in other organisms, are more likely to survive until nutrients are more plentiful. The fruiting process is thought to benefit myxobacteria by ensuring that cell growth is resumed with a group (swarm) of myxobacteria, rather than as isolated cells. Similar life cycles have developed among certain amoebae, called cellular slime moulds.

At a molecular level, initiation of fruiting body development is regulated by Pxr sRNA.^[5]^[6]

Myxobacteria such as Myxococcus xanthus and Stigmatella aurantiaca are used as model organisms for the study of development.

Clinical use[edit]

Metabolites secreted by Sorangium cellulosum known as epothilones have been noted to have antineoplastic activity. This has led to the development of analogs which mimic its activity. One such analog, known as Ixabepilone is a U.S. Food and Drug Administration approved chemotherapy agent for the treatment of metastatic breast cancer.^[7]

Various myxobacterial species as sketched by Roland Thaxter in 1892: Chondromyces crocatus (figs. 1–11), Stigmatella aurantiaca (figs. 12–19 and 25-28), Melittangium lichenicola (figs. 20–23), Archangium gephyra (fig. 24), Myxococcus coralloides (figs. 29-33), Polyangium vitellinum (figs. 34-36), and Myxococcus fulvus (figs. 37-41). Thaxter was the first taxonomist to recognize the bacterial nature of the myxobacteria. Previously, they had been misclassified as members of the fungi imperfecti.

References[edit]

^ Schneiker S et al. (2007). "Complete genome sequence of the myxobacterium Sorangium cellulosum". Nature Biotechnology 25 (11): 1281–1289. doi:10.1038/nbt1354. PMID 17965706.
^ Reichenbach H (2001). "Myxobacteria, producers of novel bioactive substances". J Ind Microbiol Biotechnol 27 (3): 149–56. doi:10.1038/sj.jim.7000025. PMID 11780785.
^ Kiskowski MA, Jiang Y, Alber MS (2004). "Role of streams in myxobacteria aggregate formation". Phys Biol 1 (3–4): 173–83. doi:10.1088/1478-3967/1/3/005. PMID 16204837.
^ Sozinova O, Jiang Y, Kaiser D, Alber M (2005). "A three-dimensional model of myxobacterial aggregation by contact-mediated interactions". Proc Natl Acad Sci USA 102 (32): 11308–12. doi:10.1073/pnas.0504259102. PMC 1183571. PMID 16061806.
^ Yu YT, Yuan X, Velicer GJ (May 2010). "Adaptive evolution of an sRNA that controls Myxococcus development". Science 328 (5981): 993. doi:10.1126/science.1187200. PMC 3027070. PMID 20489016. Retrieved 2010-07-22. Cite uses deprecated parameters (help)
^ Fiegna F, Yu YT, Kadam SV, Velicer GJ (May 2006). "Evolution of an obligate social cheater to a superior cooperator". Nature 441 (7091): 310–4. doi:10.1038/nature04677. PMID 16710413. Cite uses deprecated parameters (help)
^ "FDA Approval for Ixabepilone".

External links[edit]

The Myxobacteria Web Page
Video: Schwarmentwicklung und Morphogenese bei Myxobakterien
Video: Myxobacteria form Fruiting Bodies
Video: Myxococcus xanthus preying on an E. coli colony

English Journal

Comparison of myxobacterial diversity and evaluation of isolation success in two niches: Kiritimati Island and German compost.

Mohr KI1, Stechling M2,3, Wink J2, Wilharm E3, Stadler M1.
MicrobiologyOpen.Microbiologyopen.2015 Dec 15. doi: 10.1002/mbo3.325. [Epub ahead of print]
Myxobacteria harbor an enormous potential for new bioactive secondary metabolites and therefore the isolation of in particular new groups is of great interest. The diversity of myxobacteria present in two ecological habitats, namely sand from Kiritimati Island and German compost, was evaluated by bo
PMID 26669488

Aetherobacter fasciculatus gen. nov., sp. nov. and Aetherobacter rufus gen. nov., sp. nov., two novel myxobacteria with promising biotechnological applications.

Garcia R1, Stadler M2, Gemperlein K3, Müller R4.
International journal of systematic and evolutionary microbiology.Int J Syst Evol Microbiol.2015 Dec 4. doi: 10.1099/ijsem.0.000813. [Epub ahead of print]
Bacterial strains SBSr002T and SBSr003T were isolated in 2007 from dried soil samples containing decaying plant materials. The organisms were recognised as myxobacteria by growth stage characteristics forming swarming colony and fruiting bodies on agar and on filter paper. These strains were unusual
PMID 26637815

Myxococcus CsgA, Drosophila Sniffer, and human HSD10 are cardiolipin phospholipases.

Boynton TO1, Shimkets LJ1.
Genes & development.Genes Dev.2015 Sep 15;29(18):1903-14. doi: 10.1101/gad.268482.115. Epub 2015 Sep 3.
Myxococcus xanthus development requires CsgA, a member of the short-chain alcohol dehydrogenase (SCAD) family of proteins. We show that CsgA and SocA, a protein that can replace CsgA function in vivo, oxidize the 2'-OH glycerol moiety on cardiolipin and phosphatidylglycerol to produce diacylglycerol
PMID 26338420

Japanese Journal

Epothilons A and B: Antifungal and Cytotoxic Compounds from Sorangium cellulosum (Myxobacteria). Production, Physico-chemical and Biological Properties.:Production, Physico-chemical and Biological Properties

The Journal of Antibiotics 49(6), 560-563, 1996
NAID 130003503121

Ratjadon: A New Antifungal Compound from Sorangium cellulosum (Myxobacteria) Production, Physico-chemical and Biological Properties.:Production, Physico-chemical and Biological Properties

The Journal of Antibiotics 48(9), 973-976, 1995
NAID 130003410176

The soraphens: A family of novel antifungal compounds from Sorangium cellulosum (myxobacteria). I. Soraphen A1.ALPHA.: Fermentation, isolation, biological properties.:I. SORAPHEN A<sub>1α</sub>: FERMENTATION, ISOLATION, BIOLOGICAL PROPERTIES