English: This photomicrograph reveals Clostridium perfringens grown in Schaedler’s broth using Gram-stain. Clostridium perfringens is a spore-forming, heat-resistant bacterium that can cause foodborne disease. The spores persist in the environment, and often contaminate raw food materials. These bacteria are found in mammalian feces, and soil. Polski: Mikrofotografia laseczek Clostridium perfringens. (Photo credit: Wikipedia)