1. IDENTIFYING CHARACTERISTICS
The vegetative cells of all myxobacterial are aerobic; gram negative, elongated rods with either rounded or tapered ends. They glide in water films across solid surfaces, secreting slime (polysaccharide) tracks in which many cells migrate to produce swarms of cells that lead to the formation of fruiting bodies. This does not occur as long as sufficient nutrients are present to support vegetative growth. At the onset of nutrient depletion the cells migrate back along the slime tracks, aggregating by chemotaxis, to form large concentrations of cells. These aggregates then develop into fruiting bodies that are raised above the agar surface. As the vegetative cells migrate upward into the fruiting body they undergo a progressive differentiation into rounded myxospores. Some grow by utilizing cellulose, but many of them feed by secreting antibiotics to kill other bacteria and then produce enzymes to lyse the cells of their prey.
The above picture shows Myxococcus xanthus.
3. ISOLATION AND ECOLOGY
Myxococcus species are easily cultivated on media containing a mixture of amino acids that the myxobacteria use as carbon and energy sources; they do not readily utilize carbohydrates. Myxococcus species produce simple fruiting bodies in which the stalk is composed of vegetative cells and slime. These structures typically develop a bright yellow, red or brown pigmentation. Myxobacteria can be grown in the laboratory on media containing peptone or casein hydrolysate, which provides organic nutrients in the form of amino acids or small peptides.
Myxococcus bacteria are commonly found in animal feces and organic rich soils that are neutral or alkaline. Fruiting bodies often develop on dung pellets in a moist environment following incubation. Myxobacteria are chemoorganotrophic soil bacteria that live by consuming dead organic matter or other bacterial cells.
The image to the left shows colonies of Myxococcus growing from a central streak on an agar plate.
Dworkin, M., and D. Kaiser (eds.) 1993. Myxobacteria II. American Society for Microbiology.
Spormann, A. M., and D. Kaiser. 1999. Gliding mutants of Myxococcus xanthus with high reversal frequencies and small displacements. J. Bacteriol.181(8):2593-2601.
Rodriguez-Soto, J. P., and D. Kaiser. 1997. Identification and localization of the Tgl protein, which is required for Myxococcus xanthus social motility. J Bacteriol. 179:4372-81.
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