Sphingobacterium detergens sp. nov., a surfactant-producing bacterium isolated from soil

Abstract

A novel Gram-negative-staining strain, designated 6.2ST, was isolated from a soil sample and identified as a biosurfactant producer. Its taxonomic position was investigated using a polyphasic approach. The cells were non-motile, non-spore-forming rods. The organism grew optimally at 30-37 °C, with 0–3 % (w/v) NaCl, and at pH 7.0. Based on 16S rRNA gene sequence analysis, strain 6.2ST was found to be a member of the genus Sphingobacterium and was most closely related to four type species of the genus, showing sequence similarities of 96.8–98.9 %. Partial chaperonin 60 (cpn60) gene sequence analysis was useful in resolving the phylogenetic relationships between strain 6.2ST and closely related taxa, with similarities ranging from 85.5 % (with Sphingobacterium thalpophilum DSM 11723T) to 90.3 % (with Sphingobacterium canadense CR11T and Sphingobacterium multivorum JCM 21156T). The results of DNA–DNA hybridization experiments between the novel strain and its closest relatives gave a DNA–DNA relatedness value of less than 70 %, and consequently confirmed that this new strain did not belong to a previously described species of the genus Sphingobacterium . The major fatty acids were summed feature 3 (iso-C15 : 0 2 OH and/or C16 : 1ω7c); iso-C15 : 0; iso-C17 : 0 3-OH and C16 : 0. The G+C content of the genomic DNA was 40.0 mol%. According to its phenotypic and genotypic characteristics and the phylogenetic data, strain 6.2ST represents a novel species of the genus Sphingobacterium , for which the name Sphingobacterium detergens sp. nov. is proposed. The type strain is 6.2ST ( = CECT 7938T = LMG 26465T).