The spirochetes are heterogenous group of gram – ve bacteria that have a distinctive cell structure.

Spirochetes have a cylindrical body, unicellular helical or spiral and is intertwined with an axial filament, a bundle of fibrils that winds around the cell body.

Cytoplasm of spirochetes is surrounded by a cytoplasmic membrane and a peptidoglycan layer contributes to cell rigidity and shape. Spirochetes have a typical gram – ve cell wall, and a well developed periplasmic  space that encloses the flagella called endoflagella (axial filament).

The spirochetes are classified in the order spirochaetales which contain two families and five genera. The majority of spirochetes are free living saprobes or commensalism of animals and are not primary pathogens. But three genera that contain major human pathogens are Treponema, Leptospira and Borrelia.

Movement In Spirochetes

Spirochetes are all very actively motile. On surface spirochetes can glide, creeping is the better term for the motility of spirochetes rather then gliding. They also show an ‘inchworm’ like motility, in which one end of the cell attaches to the surface, and the other end attaches nearby: the first end then detaches and reattaches at a distance. Repitition of these steps result in relatively rapid movement.

Reproduction in Spirochetes

Most spirochetes are unicellular and show a division by binary fission.  This binary division can be spotted by the appearance of a new set of endoflagella originating at the middle of the cell. A septum then is laid down between the basal bodies, and the two daughter cells separate.

Symbiosis With Invertebrates Animals

The hindgut of termites and wood-eating roaches is a fermentation chamber in which ingested cellulose is fermented by the microbial inhabitants. The microbial flora of many of which are attached to the surface of the protozoa.

characteristic features of spirochetes in pure culture
characteristic features of spirochetes in pure culture
principal human diseases caused by spirochetes

Gaurav Singh

Editor in Chief Medical Microbiology & Recombinant DNA Technology (RDT) Labs - RDT Labs Magazine

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