Flavobacterium rivuli sp. nov., Flavobacterium subsaxonicum sp. nov., Flavobacterium swingsii sp. nov. and Flavobacterium reichenbachii sp. nov., isolated from a hard water rivulet

Abstract

Strains WB 3.3-2(T), WB 3.2-61(T), WB 4.1-42(T) and WB 2.3-68(T) were isolated from the Westerhöfer Bach hard water rivulet, North Germany. The strains were Gram-staining-negative and catalase-, aminopeptidase- and oxidase-positive. The novel strains lacked flagella and only strain WB3.2-61(T) showed gliding motility. Isolates WB 3.2-61(T), WB 4.1-42(T) and WB 2.3-68(T) produced flexirubin pigments. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel strains showed <98.2 % similarity to the type strains of all recognized species of the genus Flavobacterium. Strains WB 3.3-2(T) and WB 4.1-42(T) shared 96.3 % sequence similarity and were only distantly related to the type strains of all of the members of the genus Flavobacterium. Strain WB 3.2-61(T) branched adjacent to Flavobacterium limicola DSM 15094(T) (98.0 %), while strain WB 2.3-68(T) was a neighbour of Flavobacterium psychrophilum DSM 3660(T) (97.1 %). On R2A medium, iso-C(15 : 0) was the common major fatty acid; fatty acids C(15 : 0), C(16 : 0), iso-C(15 : 0) 3-OH, iso-C(17 : 1)omega9c, iso-C(17 : 0) 3-OH and summed feature 3 (comprising C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH) occurred in all strains though sometimes in low amounts. Metabolic properties revealed clear differences between the four isolates as well as between the isolates and their nearest phylogenetic neighbours. The lack of close relatedness was confirmed by Riboprinter and MALDI-TOF analyses of cell extracts. On the basis of a high number of phenotypic differentiating properties and phylogenetic uniqueness, four novel Flavobacterium species are proposed with the following names: Flavobacterium rivuli (type strain WB 3.3-2(T)=DSM 21788(T)=CIP 109865(T)), Flavobacterium subsaxonicum (type strain WB 4.1-42(T)=DSM 21790(T)=CIP 109867(T)), Flavobacterium swingsii (type strain WB 2.3-68(T)=DSM 21789(T)=CIP 109868(T)) and Flavobacterium reichenbachii (type strain WB 3.2-61(T)=DSM 21791(T)=CIP 109866(T)).