Sphingobacterium caeni sp. nov., isolated from activated sludge

Abstract

The taxonomic status of a bacterium, strain DC-8T, isolated from activated sludge, was determined using a polyphasic taxonomic approach. The cells of strain DC-8T were Gram-negative, non-motile, non-spore-forming and rod-shaped. The isolate grew at temperature range of 10–40 °C (optimum 30–35 °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-8T was MK-7 and major fatty acids were summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c; 39.7 %), iso-C15 : 0 (33.7 %) and C16 : 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-8T was a member of the genus Sphingobacterium . Strain DC-8T shared the highest similarity with Sphingobacterium siyangense SY1T (98.4 %), Sphingobacterium multivorum IAM 14316T (98.3 %), Sphingobacterium canadense CR11T (98.0 %) and Sphingobacterium detergens 6.2ST (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-8T 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-8T 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-8T ( = CCTCC AB 2012020T = KACC 16850T).