Myxobacteria


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, eg 9–10 million nucleotides Sorangium cellulosum has the largest bacterial genome,[needs update] at 130 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 the extracellular enzymes that 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 the cell[2]

Contents

  • 1 Life cycle
  • 2 Clinical use
  • 3 References
  • 4 External links

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 molds

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 US Food and Drug Administration approved chemotherapy agent for the treatment of metastatic breast cancer[7]

Myxobacteria are also known to produce Gephyronic acid, an inhibitor of eukaryotic protein synthesis and a potential agent for cancer chemotherapy[8]

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

  1. ^ Schneiker S, et al 2007 "Complete genome sequence of the myxobacterium Sorangium cellulosum" Nature Biotechnology 25 11: 1281–1289 doi:101038/nbt1354 PMID 17965706 
  2. ^ Reichenbach H 2001 "Myxobacteria, producers of novel bioactive substances" J Ind Microbiol Biotechnol 27 3: 149–56 doi:101038/sjjim7000025 PMID 11780785 
  3. ^ Kiskowski MA, Jiang Y, Alber MS 2004 "Role of streams in myxobacteria aggregate formation" Phys Biol 1 3–4: 173–83 doi:101088/1478-3967/1/3/005 PMID 16204837 
  4. ^ 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:101073/pnas0504259102 PMC 1183571 PMID 16061806 
  5. ^ Yu YT, Yuan X, Velicer GJ May 2010 "Adaptive evolution of an sRNA that controls Myxococcus development" Science 328 5981: 993 doi:101126/science1187200 PMC 3027070 PMID 20489016 Retrieved 2010-07-22 
  6. ^ 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:101038/nature04677 PMID 16710413 
  7. ^ "FDA Approval for Ixabepilone" 
  8. ^ SASSE, FLORENZ; STEINMETZ, HEINRICH; HÖFLE, GERHARD; REICHENBACH, HANS 2006-04-19 "Antibiotics from gliding bacteria No61 Gephyronic Acid, a Novel Inhibitor of Eukaryotic Protein Synthesis from Archangium gephyra Myxobacteria Production, Isolation, Physico-chemical and Biological Properties, and Mechanism of Action" The Journal of Antibiotics 48 1: 21–25 doi:107164/antibiotics4821 

External links

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


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