Bacterial Gliding Movement

Bacterial Structure
Part 1
Structure of Fimbriae or Pili
Functions of Fimbriae or Pili
Parts of Flagella
Bacterial Movement
Spirochaetal Movement
Gliding Movement
Nucleoid (Nucleus)
Plasmids
Classes of Plasmids
Gene Pickup and Sex Factors
R Plasmids
Plasmids Conferring Pathogenecity to mammals
Col Plasmids
Degradative Plasmids
Mercury Resistance Plasmids
Tumor Inducing Plasmid in Agrobacterium Tumifaciens
Cryptic Plasmids
Staphylococcal Plasmids

Bacterial Gliding Movement

	Bacterial Gliding Movement - Gliding movement requires a solid, moist surface on which the bacterial cells can move. It is found in all species of myxobacteria (order Myxobactera/es) and order Cytophagales, many species of the Cyanobacteria and some species of Mycoplasma. Of these, the first three groups have cell walls of the gram negative type, while the my coplasmas lack a rigid cell wall. The movement is normally long continued, and is important to the life cycle of the organisms.
In the Myxobacterales the movement is important in aggregation and formation of the fruiting body. In the Myxobacterales and Cytophagales the movement enables the organisms to locate substrates like wood, bark, chitinous shells and bacteria in dung, which their strong enzymes reduce to nutrients. Doetsch and Hageage have grouped the hypotheses for gliding mechanisms into four categories:
(i) gradient of osmotic forces along the cell, (ii) generation of surface tension due to localized secretion of surface-active material, (iii) pushing of the cells by localized secretion of slime, and (iv) the contractile wave hypothesis, according to which there is generation of contractile waves in the bacterial cell. The last hypothesis is best supported on the basis of available evidence. Gliding bacteria do not appear to have external appendages and internal filaments, with the exception of polar tufts of fimbriae. The secretion of slime by most gliding bacteria is probably correlated with an adhesive or lubricant function
Neither the presence of fimbriae nor the secretion of slime is exclusive to gliders. It has, however, been found that non-motile mutants of the Cytophaga1es have lost their fimbriae. In Oscillatoria princeps, a parallel array of 5-8 nm thick fibrils are present near the cell surface, and are helically arranged around the cell. Rotation and forward movement in this organism is accounted for by waves of bending passing along the fibrils. The gliding mechanism is reversibly damaged by proteolytic enzymes, chelators and osmotic shock. In Myxococcus xanthus, gliding stops on treatment with the enzyme pronase, indicating the involvement of a gliding protein. Treated cells- recovered their motility within an hour. Treatment with chloramphenicol, which inhibits protein synthesis, prevents recovery of gliding.
	This supports the involvement of a protein. No gliding protein has, however, been identified as yet. Mycoplasmas have contractile material in the cytoplasm or membrane. They show wriggling rather than gliding movements.

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