Sphingobacterium caeni sp nov., isolated from activated sludge

The taxonomic status of a bacterium, strain DC-8(T), isolated from activated sludge, was determined using a polyphasic taxonomic approach. The cells of strain DC-8(T) were Gram-negative, non-motile, non-spore-forming and rod-shaped. The isolate grew at temperature range of 10-40 degrees C (optimum 30-35 degrees C), pH range of 5.0-10.0 (optimum 6.5-8.0) and NaCl concentrations of 0-5 % (optimum 0-1%). The predominant menaquinone of strain DC-8(T) was MK-7 and major fatty acids were summed feature 3 (C-16:1 omega 6c and/or C-16:1 omega 7c; 39.7%), iso-C-15:0 (33.7%) and C-16:0 (5.2%). The DNA G+C content was 39.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that strain DC-8(T) was a member of the genus Sphingobacterium. Strain DC-8(T) shared the highest similarity with Sphingobacterium siyangense SY1(T) (98.4 %), Sphingobacterium multivorum IAM 14316(T) (98.3 %), Sphingobacterium canadense CR11(T) (98.0%) and Sphingobacterium detergens 6.2S(T) (97.9 %) and shared less than 97% similarity with other members of the genus Sphingobacterium. DNA DNA hybridization experiments showed that the DNA DNA relatedness values between strain DC-8(T) and its closest phylogenetic neighbours were below 70%. Based on the phylogenetic analysis, DNA DNA hybridization, whole-cell fatty acid composition as well as biochemical characteristics, strain DC-8(T) was clearly distinguished from all recognized species of the genus Sphingobacterium and should be classified as a representative of a novel species of the genus Sphingobacterium, for which the name Sphingobacterium caeni sp. nov. is proposed. The type strain is DC-8(T) (=CCTCC AB 2012020(T)=KACC 16850(T)).