English: This photomicrograph of a Leifson flagella-stained specimen, revealed the presence of a single, flagellated, Bacillus subtilis bacterium. The use of a special flagellar staining process enabled visualization of the organisms’ peritrichous flagellae, which are invisible, when processed using Gram-stain technique, and observed under a light microscope. B. subtilis is a Gram-positive, endospore-forming bacterium that is present throughout the environment, including the gastrointestinal tract of ruminants and humans.