Myxobacteria

Fruiting bodies of Myxococcus xanthus.

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

Characteristics, lifestyle

Myxobacteria do not have flagella, but may move actively by gliding over solid surfaces. They form swarms of thousands of cells by intercellular signals ( neurotransmitters ) are held together. It is believed that the high number of individuals facilitates the feeding of other microorganisms and undissolved organic compounds, since the concentration of emitted digestive enzymes is increased. The sliding mechanism is not known yet.

When food is scarce, the cells flow together by chemotaxis to form fruiting bodies. These fruiting bodies can take different forms depending on the type and colors. In the fruiting bodies, the cells initially form elongated vegetative cell body, which then evolve with the formation of thicker cell walls to round myxospores. These spores are protected from dehydration and have only minor metabolism. When resting stages they can take to improve the food situation. The ability to fruiting body formation that most, but not all myxobacteria. Anaeromyxobacter dehalogenans example, is an obligate anaerobic living representative, in which not have a fruiting bodies could be detected. Under laboratory conditions, some myxobacteria can be induced to form spores and other substances by the addition of glycerol, dimethyl sulfoxide ( DMSO) without first fruiting bodies. The way how these substances activate the genetic program of sporulation is not yet known.

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

Due to their complex life cycle are the subject of various research projects myxobacteria. The genomes of some representatives were sequenced ( M. xanthus, Anaeromyxobacter dehalogenans, and Sorangium cellulosum Stigmatella aurantiaca ). The myxobacteria have - compared to other prokaryotes - very large genomes, which consist of approximately 9-12 million base pairs. The genome of Sorangium cellulosum with more than 13 million base pairs, the biggest of all so far ( 2007) sequenced bacterial genomes.

Importance

Myxobacteria produce a series of medically and industrially useful chemical substances, such as antibiotics and anti-proliferative agent for the fight against cancer ( epothilones ).

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

Taxonomic outline

The order Myxococcales is divided into six families:

• Cystobacteraceae
• Myxococcaceae
• Polyangiaceae
• Nannocystaceae
• Haliangiaceae
• Kofleriaceae