spirillum

Spirillum is a genus of Gram-negative, motile bacteria characterized by a slender, helical or spiral cell body. The cells are non-spore-forming and typically possess one or more flagella, often distributed at the ends of the cell, enabling distinctive screw-like movement.

Habitat and ecology: They are primarily aquatic organisms, found in freshwater and marine environments, as well as moist soils and decaying organic matter. Many species live as free-living saprophytes, while others may associate with biofilms or aquatic organisms. They are generally aerobic or facultatively aerobic and rely on organic compounds for energy and carbon, though metabolic capabilities vary by species.

Reproduction and growth: Spirillum reproduce by binary fission. They do not form endospores. Growth range and requirements vary; some species tolerate moderate salinity.

Taxonomy and diversity: The genus comprises multiple described species and is part of the larger group of Gram-negative, non-spore-forming bacteria. Many environmental isolates have been described from diverse habitats.

Clinical relevance: While most Spirillum species are environmental, a minority have been associated with human infections. Historically, Spirillum minus has been linked to rat-bite fever in parts of Asia; such infections are uncommon. Prompt identification in clinical labs can be difficult due to slow growth and resemblance to other Gram-negative bacteria.