Neisseriales

Neisseriales is an order of bacteria in the class Betaproteobacteria, phylum Pseudomonadota. It contains two families: Neisseriaceae and Chromobacteriaceae. Organisms in this order are Gram-negative and show diverse morphologies and metabolisms.

Neisseriaceae includes Gram-negative cocci, typically arranged as diplococci, that colonize the mucous membranes of humans and other animals. The most well-known genus, Neisseria, includes pathogenic species such as Neisseria meningitidis and Neisseria gonorrhoeae, which are associated with meningitis, septicemia, and sexually transmitted infections, as well as nonpathogenic commensal species.

Chromobacteriaceae comprises predominantly environmental, Gram-negative rods that inhabit soil and water, often in tropical or subtropical regions. The best-known genus, Chromobacterium, includes Chromobacterium violaceum, which produces the pigment violacein and can cause rare opportunistic infections in humans.

Ecology and physiology: Members of Neisseriales are mainly aerobic or facultatively anaerobic and oxidase-positive. They are found in a range of habitats, from human-associated surfaces to environmental reservoirs. Clinically important species in Neisseria underscore the relevance of this order to medicine, while environmental members contribute to nutrient cycling and biodiversity.

Taxonomy: The order Neisseriales was defined to group these related lineages within Betaproteobacteria; molecular studies continue to refine interrelationships among its members.