False-colour transmission electron micrograph (TEM) of a Clostridium perfringens bacterium with endospore. This species of Gram-positive, spore- forming soil bacteria is seen towards the end of spore formation (sporulation). At lower centre, it has developed an endospore (green) with membrane (red). This is a resting phase induced by adverse conditions, & the spore will germinate when condi- tions become favourable. C.perfringens causes blood poisoning, food poisoning & gas gangrene in humans. It produces an exotoxin (alpha-toxin) that can digest human tissue, and contaminate meat food sources. Magnification: x20,000 at 6x7cm size.