Myxobacteria

Myxobacteria

Myxobacteria
Myxococcus xanthus
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Deltaproteobacteria
Order: Myxococcales

The myxobacteria ("slime bacteria") are a group of 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 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

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

Life cycle

When nutrients are scarce, myxobacterial cells aggregate into fruiting bodies (not to be confused with 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 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

  1. ^ Schneiker S, et al. (2007). "Complete genome sequence of the myxobacterium Sorangium cellulosum". Nature Biotechnology 25 (11): 1281–1289.  
  2. ^ Reichenbach H (2001). "Myxobacteria, producers of novel bioactive substances". J Ind Microbiol Biotechnol 27 (3): 149–56.  
  3. ^ Kiskowski MA, Jiang Y, Alber MS (2004). "Role of streams in myxobacteria aggregate formation". Phys Biol 1 (3–4): 173–83.  
  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.  
  5. ^ Yu YT, Yuan X, Velicer GJ (May 2010). "Adaptive evolution of an sRNA that controls Myxococcus development". Science 328 (5981): 993.  
  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.  
  7. ^ "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