Spirochaete

Spirochaetes (or Spirochetes) are the phylum Spirochaetae. These are double-membrane bacteria with long, helically coiled (spiral-shaped) cells. 
Spirochaetes are bacteria. They have flagella, which run lengthwise between the cell wall and outer membrane. The flagella cause a twisting motion which moves the spirochaete about. 
Most spirochaetes are free-living and anaerobic, but there are many parasitic species.
Classification.
The spirochaetes are divided into three families (Brachyspiraceae, Leptospiraceae, and Spirochaetaceae). They are all put in a single order, the Spirochaetales. Disease-causing members of this phylum include: