Sphingomonas segetis sp. nov., isolated from spinach farming field soil

A Gram-stain-negative bacterium, designated strain YJ09^T, was isolated from spinach farming field soil at Shinan in the Republic of Korea. Cells of strain YJ09^T were found to be strictly aerobic, non-motile, non-spore-forming creamy-yellow rods which can grow at 20-37 °C (optimum, 30 °C), at pH 6.0-9.0 (optimum, pH 7.0-8.0) and at salinities of 0-0.5 % (w/v) NaCl (optimum, 0 % NaCl). The 16S rRNA gene sequence analysis showed that strain YJ09^T belongs to the genus Sphingomonas with high sequence similarities to Sphingomonas parvus GP20-2 ^T (98.0 %), Sphingomonas agri HKS-06^T (97.7 %) and Sphingomonas lutea JS5^T (97.4 %). The results of phylogenetic analysis indicated that strain YJ09^T formed a distinct phyletic line in the genus Sphingomonas and the results of DNA-DNA relatedness studies demonstrated that strain YJ09^T could be separated from its closest relatives in the genus Sphingomonas. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified glycolipids, an unidentified phospholipid and sphingoglycolipid. The predominant ubiquinone and polyamine components were Q-10 and spermidine, respectively. The major fatty acids were C_18:1  ω7c, C_{16  : 0} and C_16:1  ω7c and/or iso-C_15 : 0 2-OH. The DNA G+C content of this novel isolate was 65.9 mol%. On the basis of phenotypic, chemotaxonomic properties and phylogenetic analyses in this study, strain YJ09^T is considered to represent a novel species in the genus Sphingomonas, for which the name Sphingomonas segetis sp. nov. is proposed. The type strain is YJ09^T (=KACC 19551^T=NBRC 113247^T).