Spirochete bacteria, coloured transmission electron micrograph (TEM). Spirochetes are bacteria with helically coiled cells. They contain filamentous flagella (axial filaments) that run lengthwise between the cell membrane and outer membrane. The twisting motion of the flagella allows the bacterium to move about. Here however, the bacteria have been damaged, causing the flagella to break away from the sheaths. Disease causing members of this phylum include Borrelia burgdorferi, which causes Lyme disease and Treponema pallidum, which causes syphilis. Magnification: x13,000 when printed 10 centimetres wide.