LM of several spiral-shaped spirochaetes bacteria seen amongst a pool of unidentified rod-shaped bacteria. SA spirochete is a member of the phylum Spirochaetes, which contains distinctive diderm (double-membrane) bacteria, most of which have long, helically coiled (corkscrew-shaped or spiraled) cells. Spirochaetes stain gram-negative and are chemoheterotrophic in nature. Spirochetes are distinguished from other bacterial phyla by the location of their flagella, sometimes called axial filaments, which run lengthwise between the bacterial inner membrane and outer membrane in periplasmic space. These cause a twisting motion which allows the spirochaete to move about. When reproducing, a spirochaete will undergo asexual transverse binary fission. Most spirochaetes are free-living and anaerobic, but there are numerous exceptions. Spirochaetes bacteria are diverse in their pathogenic capacity, the ecological niches that they inhabit, as well as molecular characteristics including GC content and genome size. Magnification: x107 at 35mm size.