False-colour transmission electron micrograph (TEM) of Corynebacterium minutissimum, showing a single bacterium of the Gram positive, non- sporing, aerobic species of bacilli (rod-shaped bacteria). The Corynebacterium genus includes an important human pathogen, C. diphtheriae the causative agent of diphtheria; other species cause suppurative (pus forming) diseases of animals. An assortment of non- pathogenic species, known as diptheroid bacilli, occur as normal flora of human skin, upper respiratory tract, external ears and conjunctivae (mucous membranes of eye & inner eyelid). Magnification: X 26,500 at 35mm size.