Flavobacteriales

Flavobacteriales is an order of bacteria within the class Flavobacteriia of the phylum Bacteroidota. Members are Gram-negative, non-spore-forming, and typically rod-shaped; many produce yellow-pigmented colonies due to flexirubin-type pigments. They are predominantly aerobic or facultatively anaerobic chemoorganotrophs with diverse lifestyles, ranging from free-living environmental inhabitants to symbionts and, in some cases, pathogens.

Taxonomically, Flavobacteriales comprises multiple families, with Flavobacteriaceae among the largest. The order has undergone revisions as molecular phylogenetics clarified relationships, leading to the inclusion of related lineages such as Weeksellaceae and other families. Genera within Flavobacteriales include the well-known Flavobacterium and related taxa that contribute to environmental or clinical contexts.

Ecology and metabolism play central roles for Flavobacteriales. They occur widely in fresh and marine waters, soils, and sediments and are often associated with plants and animals. They participate in the degradation of organic matter and possess a broad array of carbohydrate-active enzymes that enable breakdown of complex polymers. Gliding motility is common in many members, aiding surface colonization and biofilm formation.

Clinical relevance and significance extend beyond the environment. Some Flavobacteriales species are opportunistic pathogens in humans, particularly in hospital settings and among immunocompromised individuals. In aquatic systems, several species are notable fish pathogens, causing diseases such as columnaris. Genomic studies highlight large repertoires of enzymes for polysaccharide utilization and adaptation to diverse ecological niches.