Flavobacterium lotistagni sp. nov. and Flavobacterium celericrescens sp. nov., isolated from freshwater habitats

This study presents taxonomic descriptions of strains CYK-4(T) and TWA-26(T) isolated from freshwater habitats in Taiwan. Both strains were Gram-stain-negative, strictly aerobic, motile by gliding and rod-shaped. Phylogenetic analyses based on 16S rRNA gene sequences and coding sequences of 92 protein clusters indicated that both strains belonged to the genus Flavobacterium. Analysis of 16S rRNA gene sequences showed that strains CYK-4(T) and TWA-26(T) shared 92.7 % sequence similarity and were most closely related to Flavobacterium ovatum W201E(T) (95.6%) and Flavobacterium aquaticum JC164(T) (96.7 %), respectively. Both strains shared common chemotaxonomic characteristics comprising MK-6 as the main isoprenoid quinone, iso-C-15:0 and iso-C-15:1 G as the predominant fatty acids, phosphatidylethanolamine as the principal polar lipid, and homospermidine as the major polyamine. The DNA G+C contents of strains CYK-4(T) and TWA- 26(T) were 41.5 and 31.8 mol%, respectively. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization values between these two novel isolates and their closest relatives were below the cut-off values of 95-96, 90 and 70 %, respectively, used for species demarcation. On the basis of phenotypic and genotypic properties and phylogenetic inference, both strains should be classified as novel species within the genus Flavobacterium, for which the names Flavobacterium lotistagni sp. nov. (type strain CYK-4(T)=BCRC 81192(T)=LMG 31330(T)) and Flavobacterium celericrescens sp. nov. (type strain TWA-26(T)=BCRC 81200(T)=LMG 31333(T)) are proposed.