Sphingobium barthaii sp. nov., a high molecular weight polycyclic aromatic hydrocarbon-degrading bacterium isolated from cattle pasture soil

<jats:p>A Gram-stain-negative, yellow, rod-shaped bacterium, designated strain KK22<jats:sup>T</jats:sup>, was isolated from a microbial consortium that grew on diesel fuel originally recovered from cattle pasture soil. Strain KK22<jats:sup>T</jats:sup>has been studied for its ability to biotransform high molecular weight polycyclic aromatic hydrocarbons. On the basis of 16S rRNA gene sequence phylogeny, strain KK22<jats:sup>T</jats:sup>was affiliated with the genus<jats:italic>Sphingobium</jats:italic>in the phylum<jats:italic>Proteobacteria</jats:italic>and was most closely related to<jats:italic>Sphingobium fuliginis</jats:italic>TKP<jats:sup>T</jats:sup>(99.8  %) and less closely related to<jats:italic>Sphingobium quisquiliarum</jats:italic>P25<jats:sup>T</jats:sup>(97.5  %). Results of DNA–DNA hybridization (DDH) revealed relatedness values between strain KK22<jats:sup>T</jats:sup>and strain TKP<jats:sup>T</jats:sup>and between strain KK22<jats:sup>T</jats:sup>and strain P25<jats:sup>T</jats:sup>of 21 ± 4  % (reciprocal hybridization, 27 ± 2  %) and 15 ± 2  % (reciprocal hybridization, 17 ± 1  %), respectively. Chemotaxonomic analyses of strain KK22<jats:sup>T</jats:sup>showed that the major respiratory quinone was ubiquinone Q-10, that the polar lipid profile consisted of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidyl-<jats:italic>N</jats:italic>-methylethylethanolamine and sphingoglycolipid, and that C<jats:sub>18 : 1</jats:sub>ω7<jats:italic>c</jats:italic>and C<jats:sub>14 : 0</jats:sub>2-OH were the main fatty acid and hydroxylated fatty acids, respectively. This strain was unable to reduce nitrate and the genomic DNA G+C content was 64.7 mol%. Based upon the results of the DDH analyses, the fact that strain KK22<jats:sup>T</jats:sup>was motile, and its biochemical and physiological characteristics, strain KK22<jats:sup>T</jats:sup>could be separated from recognized species of the genus<jats:italic>Sphingobium</jats:italic>. We conclude that strain KK22<jats:sup>T</jats:sup>represents a novel species of this genus for which the name<jats:italic>Sphingobium barthaii</jats:italic>sp. nov. is proposed; the type strain is KK22<jats:sup>T</jats:sup>( = DSM 29313<jats:sup>T</jats:sup> = JCM 30309<jats:sup>T</jats:sup>).</jats:p>