The family flavobacteriaceae

Abstract

The family Flavobacteriaceae is the largest family in the phylum Bacteroidetes. It contains at least 90 genera and hundreds of species. Members of the family are found in a wide variety of marine, freshwater, and soil habitats, and some are also associated with animals or plants. In spite of this diversity, some generalities regarding members of the family can be identified. Most, but not all, are aerobic, with primarily respiratory metabolism. Menaquinones of type 6 (MK6) are the major respiratory quinones and help to distinguish members of the family Flavobacteriaceae from many other families within the phylum Bacteroidetes. Most species have rod-shaped cells, with some of them exhibiting long filamentous cells. Utilization of macromolecules such as polysaccharides and proteins is a common feature of many members of the family. Polysaccharide utilization appears to involve novel cell-surface machinery common to members of the phylum Bacteroidetes to bind polysaccharides and transport oligomers across the outer membrane. Many, but not all, genera and species move over surfaces by a form of gliding motility that appears to be confined to members of the phylum Bacteroidetes. Genome analyses suggest that most members of the family also use a novel protein secretion system referred to as the Por secretion system to secrete proteins beyond the outer membrane. There are no known photosynthetic flavobacteria, but some marine members of the Flavobacteriaceae use proteorhodopsin to harvest light energy and supplement their energy needs. The family Flavobacteriaceae includes important fish pathogens such as Flavobacterium psychrophilum, Flavobacterium columnare, and Tenacibaculum maritimum; bird pathogens such as Riemerella anatipestifer, Ornithobacterium rhinotracheale, and Coenonia anatina; human pathogens such as Capnocytophaga canimorsus and Elizabethkingia meningoseptica; and numerous bacteria of environmental and biotechnological significance.