関: myxobacterium、Myxococcales、Myxococcus、Sorangium cellulosum

WordNet

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）』「2014/05/12 09:25:12」(JST)

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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

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

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

^ 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.
^ 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.
^ "FDA Approval for Ixabepilone".

External links

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

Effects of Elevated Atmospheric CO2 on Microbial Community Structure at the Plant-Soil Interface of Young Beech Trees (Fagus sylvatica L.) Grown at Two Sites with Contrasting Climatic Conditions.

Gschwendtner S1, Leberecht M, Engel M, Kublik S, Dannenmann M, Polle A, Schloter M.
Microbial ecology.Microb Ecol.2015 May;69(4):867-78. doi: 10.1007/s00248-014-0527-x. Epub 2014 Nov 5.
Soil microbial community responses to elevated atmospheric CO2 concentrations (eCO2) occur mainly indirectly via CO2-induced plant growth stimulation leading to quantitative as well as qualitative changes in rhizodeposition and plant litter. In order to gain insight into short-term, site-specific ef
PMID 25370887

devI is an evolutionarily young negative regulator of Myxococcus xanthus development.

Rajagopalan R1, Wielgoss S2, Lippert G2, Velicer GJ2, Kroos L3.
Journal of bacteriology.J Bacteriol.2015 Apr;197(7):1249-62. doi: 10.1128/JB.02542-14. Epub 2015 Feb 2.
During starvation-induced development of Myxococcus xanthus, thousands of rod-shaped cells form mounds in which they differentiate into spores. The dev locus includes eight genes followed by clustered regularly interspaced short palindromic repeats (CRISPRs), comprising a CRISPR-Cas system (Cas stan
PMID 25645563

The enhancer binding protein Nla6 regulates developmental genes that are important for Myxococcus xanthus sporulation.

Giglio KM1, Zhu C1, Klunder C1, Kummer S1, Garza AG2.
Journal of bacteriology.J Bacteriol.2015 Apr;197(7):1276-87. doi: 10.1128/JB.02408-14. Epub 2015 Feb 2.
In the bacterium Myxococcus xanthus, starvation triggers the formation of multicellular fruiting bodies containing thousands of stress-resistant spores. Recent work showed that fruiting body development is regulated by a cascade of transcriptional activators called enhancer binding proteins (EBPs).
PMID 25645554

Identification of a putative flavin adenine dinucleotide-binding monooxygenase as a regulator for Myxococcus xanthus development.

Cao S1, Wu M1, Xu S1, Yan X2, Mao X3.
Journal of bacteriology.J Bacteriol.2015 Apr;197(7):1185-96. doi: 10.1128/JB.02555-14. Epub 2015 Jan 20.
Gene clusters coding for the chaperone/usher (CU) pathway are widely distributed in many important environmental and pathogenic microbes; however, information about the regulatory machineries controlling CU gene expression during multicellular morphogenesis is missing. The Myxococcus xanthus Mcu sys
PMID 25605309

Japanese Journal

Two New Ring-Contracted Congeners of Rhizopodin Illustrate Significance of the Ring Moiety of Macrolide Toxins on the Actin Disassembly-Mediated Cytotoxicity

Oku Naoya,Matsumoto Ayaka,Matsunaga Takayuki [他]
Chemical and pharmaceutical bulletin 62(3), 294-300, 2014-03
NAID 40019992574

Two New Ring-Contracted Congeners of Rhizopodin Illustrate Significance of the Ring Moiety of Macrolide Toxins on the Actin Disassembly-Mediated Cytotoxicity

Oku Naoya,Matsumoto Ayaka,Matsunaga Takayuki,Asano Yuhki,Kasai Hiroaki,Matoba Shouhei,Igarashi Yasuhiro
Chemical and Pharmaceutical Bulletin 62(3), 294-300, 2014
Two new cytotoxic dilactones, bisisorhizopodin (1) and isorhizopodin (2), together with known divalent actin depolymerizer rhizopodin (3), were isolated from the culture broth of a myxobacterium Myxoc …
NAID 130003390773

Isolation and synthesis of falcitidin, a novel myxobacterial-derived acyltetrapeptide with activity against the malaria target falcipain-2

SOMANADHAN Brinda,KOTTURI Santosh R,LEONG Chung Yan,GLOVER Robert P,HUANG Yicun,FLOTOW Horst,BUSS Antony D,LEAR Martin J,BUTLER Mark S
Journal of antibiotics 66(5), 259-264, 2013-05-25
NAID 10031176573

A life cycle of branched aerial mycelium- and multiple budding spore-forming bacterium Thermosporothrix hazakensis belonging to the phylum Chloroflexi

Yabe Shuhei,Aiba Yoshifumi,Sakai Yasuteru,Hazaka Masaru,Yokota Akira
The Journal of General and Applied Microbiology 56(2), 137-141, 2010
… As far as known, sporulation modes in prokaryotes include formation of endospores exemplified by <I>Firmicutes </I>bacteria, myxospores by myxobacteria and arthrospores by actinomycetes. …
NAID 130004449280