Bacillus

Bacillus is a genus of Gram-positive, rod-shaped bacteria in the phylum Firmicutes. Members are typically aerobic or facultatively anaerobic and are notable for their ability to form endospores, a dormant, highly resistant cell type that allows survival under adverse conditions. The spores can persist in soil and water for long periods and can be spread by air and other vectors.

Ecology and diversity: Bacillus species are widespread in soil and aquatic environments, and they play roles in nutrient cycling, plant interactions, and biotechnology. Several species have substantial practical importance: Bacillus subtilis is a model organism and producer of industrial enzymes; Bacillus thuringiensis produces crystal proteins used as biological insecticides; Bacillus cereus can cause foodborne illness; Bacillus anthracis causes anthrax in humans and animals. The genus also includes various other species with applications in fermentation and enzyme production.

Identification and characteristics: Most Bacillus are Gram-positive, rod-shaped, and catalase-positive. They are typically motile with peritrichous flagella, though some species such as B. anthracis are non-motile. They form endospores under nutrient limitation or environmental stress, enabling long-term survival.

Clinical and safety notes: Because some Bacillus species are pathogenic or opportunistic, proper handling and sterilization are important in clinical and food settings. Spore formation complicates decontamination since spores resist heat and chemical disinfectants.