Spirochaete

Overview
Spirochetes is a phylum of distinctive Gram-negative bacteria, which have long, helically coiled cells. Spirochetes are chemoheterotrophic in nature, with lengths between 5 and 250 µm and diameters around 0.1-0.6 µm.

Spriochetes are distinguished from other bacterial phyla by the presence of flagella, sometimes called axial filaments, running lengthwise between the cell membrane and outer membrane. These cause a twisting motion which allows the spirochaete to move about.

The spirochaetes are divided into three families (Brachyspiraceae, Leptospiraceae, and Spirochaetaceae), all placed within a single order (Spirochaetales).


 * Leptospira species, which causes leptospirosis
 * Borrelia burgdorferi, which causes Lyme disease
 * Borrelia recurrentis, which causes relapsing fever
 * Treponema pallidum, which causes syphilis

Most spirochaetes are free-living and anaerobic, but there are numerous exceptions, including the above.

Cavalier-Smith has postulated that the Spirochaetes belong in a larger clade called Gracilicutes.

Historical
Salvarsan, the first antibiotic in medical history, was effective against spirochaetes only and was primarily used to cure syphilis.

It has been suggested by biologist Lynn Margulis that eukaryotic flagella were derived from symbiotic spirochaetes, but few biologists accept this, as there is no close structural similarity between the two.