Caption:
Scanning electron micrograph (SEM) of Bacillus and Clostridium. The gram-positive spore-forming bacilli are the Bacillus and Clostridium species. These bacilli are ubiquitous, and because they form spores, they can survive in the environment for many years. Whereas the Bacillus species are aerobes, the Clostridium species are anaerobes. Clostridium is a genus of Gram-positive bacteria, which includes several significant human pathogens, including the causative agent of botulism and diarrhoea. Clostridium species inhabit soils and the intestinal tract of animals, including humans. It is also a normal inhabitant of the healthy lower reproductive tract of women. Magnification is 35,000x at 15 cm image size.