Myxobacteria

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Myxobacteria
Fruiting bodies of Myxococcus xanthus.

Fruiting bodies of Myxococcus xanthus .

Systematics
Classification : Creature
Domain : Bacteria (bacteria)
Department : Proteobacteria
Class : Deltaproteobacteria
Order : Myxobacteria
Scientific name
Myxococcales
Tchan et al. 1948

The Myxobacteria or Myxobacteria (scientifically: Myxococcales) are an order of bacteria . They mainly live in the ground . You are in the transition from a single-cell to a multicellular way of life. They are assigned to the δ section of Proteobacteria , a large group of gram-negative bacteria.

Characteristics, way of life

Myxobacteria have no flagella , but can actively move over solid surfaces by sliding. They form swarms of thousands of cells that are held together by intercellular signals (messenger substances). It is believed that the high number of individuals facilitates the nutrition of other microorganisms and undissolved organic compounds, as this increases the concentration of the digestive enzymes released. The mechanism of sliding is not yet known.

When food becomes scarce, the cells chemotaxis together to form fruiting bodies . These fruit bodies can take on different shapes and colors depending on the species. In the fruiting bodies, the cells initially form elongated vegetative cell bodies, which then develop into round myxospores with the formation of thick cell walls. These spores are protected from dehydration and have only a low metabolism. As resting stages, they can survive until the nutritional conditions improve. Most, but not all, myxobacteria have the ability to produce fruiting bodies. Anaeromyxobacter dehalogenans , for example, is an obligate anaerobic living representative, in which no fruiting bodies could be detected so far. Under laboratory conditions, some myxobacteria can be induced to form spores by adding glycerine , dimethyl sulfoxide (DMSO) and other substances without first producing fruit bodies. The way in which these substances activate the genetic program for sporulation is not yet known.

The way of life, especially the formation of the fruiting body, is similar to that of the eukaryotic slime molds , an example of convergent development .

Due to their complex life cycle, myxobacteria are the subject of various research projects. The genomes of some representatives were sequenced ( Myxococcus xanthus , Anaeromyxobacter dehalogenans , Stigmatella aurantiaca and Sorangium cellulosum ). Compared to other prokaryotes, the myxobacteria have very large genomes consisting of around 9–12 million base pairs . With more than 13 million base pairs, the genome of Sorangium cellulosum is the largest of all bacterial genomes sequenced to date (2007). This is why the myxobacteria are also interesting in terms of evolutionary history.

meaning

Myxobacteria produce a number of medicinally and industrially useful chemicals, such as antibiotics and anti-proliferation drugs used to fight cancer ( epothilones ).

The world's largest collection of myxobacteria is located at the German Collection of Microorganisms and Cell Cultures ( DSMZ ) in Braunschweig.

Taxonomic breakdown

The order Myxococcales is divided into 6 families:

literature

Whitworth, D. (ed) .: Myxobacteria: Multicellularity and Differentiation. ASM Press, Washington DC, 2007, ISBN 978-1-55581-420-5

Web links