CUTTING A GORDIAN-KNOT - EMENDED CLASSIFICATION AND DESCRIPTION OF THE GENUS FLAVOBACTERIUM, EMENDED DESCRIPTION OF THE FAMILY FLAVOBACTERIACEAE, AND PROPOSAL OF FLAVOBACTERIUM-HYDATIS NOM-NOV (BASONYM, CYTOPHAGA AQUATILIS-STROHL AND TAIT 1978)

The phylogenetic positions and G+C contents of most species belonging to the genera Flavobacterium, Cytophaga, and Flexibacter and several r elated taxa were determined. Most of the strains included in this stud y belong to rRNA superfamily V, as shown by DNA-rRNA hybridization dat a, but the three main genera are highly polyphyletic, Several so-calle d Cytophaga and Flexibacter species isolated from soil and freshwater cluster,vith the type species of the genus Flavobacteirum, Flavobacter ium aquatile, and with Flavobacterium branchiophilum. The fatty acid a nd protein profiles of members of this group of organisms were determi ned. We provide an emended description of the genus Flavobacterium and propose new combinations for the following 7 of the 10 validly descri bed species included in this genus: Flavobacterium columnare, Flavobac terium flevense, Flavobacterium johnsoniae (we also correct the specif ic epithet of this taxon), Flavobacterium pectinovorum, Flavobacterium psychorophilum, Flavobacterium saccharophilum, and Flavobacterium suc cinicans. A new name, Flavobacterium hydatis, is proposed for [Cytopha ga] aquatilis Strohl and Tait 1978. The emended genus Flavobacterium c ontains bacteria that have the following main characteristics: gram ne gative rods that are motile by gliding, produce yellow colonies on aga r, are chemoorganotrophs and aerobes, decompose several polysaccharide s but not cellulose, and are widely distributed in soil and freshwater habitats. Three Flavobacterium species are pathogenic for fish, The G +C contents of Flavobacterium DNAs range from 32 to 37 mol%. An emende d description of the family Flavobacteriaceae is also provided.