Flexivirga Caeni Sp. Nov., Isolated From Activated Sludge

A Gram-stain-positive, strictly aerobic, non-motile, non-spore-forming and oval-shaped bacterium, designated strain BO-16(T) was isolated from activated sludge. In this study, we describe the taxonomic characterization and classification of this bacterium by using the polyphasic approach. Growth of BO-16(T) was observed at 10-40 degrees C (optimum, 25-37 degrees C) and at pH 5.0-10.0 (optimum, pH 7.0) on R2A agar. The major fatty acids it contained were iso-C-16:0. anteiso-C-17:0 and iso-C-17:0 and the major polar lipids were diphosphatidylglycerol, phosphatidylinositol and phosphatidylethanolamine. This isoprenoid quinones included MK-8 (H-4) and MK-8 (H-6). The peptidoglycan contained lysine, serine, alanine, glycine and glutamic acid and represented the peptidoglycan type A4 alpha. On the basis of 16S rRNA gene sequence similarity. BO-16(T) was shown to represent a member of the genus Flexivirga and to be related to Flexivirga oryzae KACC 18597(t) (98.4% sequence similarity), Flexivirga endophytica KCTC 39536(T) (97.5%), Flexivirga alba DSM 24460(T) (97.4%) and Flexivirga lutea KCTC 39625(T) (97.3%). The G+C content of the genomic DNA was 68.0 mol%. The DNA-DNA relatedness values between BO-16(T) and its closest phylogenetic neighbours were much lower than 70%. BO-16(T) could be differentiated phylogenetically and phenotypically from the species of the genus Flexivirga with validly published names. Therefore the isolate represents a novel species, for which the name Flexivirga caeni sp. nov. is proposed, with the type strain BO-16(T) (=KACC 19647(T)=LMG 30859(T)).