Sphingomonas longa sp. nov., Sphingomonas mollis sp. nov. and Sphingomonas aurea sp. nov.: three novel Sphingomonas species isolated from soil

Three Gram-negative, aerobic and non-motile bacterial strains, BT552^T, BT553^T and KR1UV-12^T, were isolated from soil samples in Gwangju-si and Gangneung-si, the Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequence showed that strains BT552^T, BT553^T and KR1UV-12^T clustered to a distinct clade within the family <i>Sphingomonadaceae</i> (order <i>Sphingomonadales</i>, class <i>Alphaproteobacteria</i>). The strains exhibited the highest genetic similarity with representatives of the genus <i>Sphingomonas</i>; moreover, strains BT552^T and BT553^T tightly clustered with <i>Sphingomonas melonis</i> DAPP-PG 224^T (98.2 and 98.1 %) and <i>Sphingomonas aquatilis</i> JSS-7^T (98.1 and 98.0 %), while strain KR1UV-12^T clustered with <i>S. melonis</i> DAPP-PG 224^T (97.9%) and <i>Sphingomonas rubra</i> BH3^T (97.8%), respectively. The major cellular fatty acids of all three strains were summed feature 8 (C_18:1 ω7c/C_18:1 ω6c), comprising 44.7, 46.4 and 48.5%. Additionally, their respiratory quinone is Q-10, and polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phospholipids, sphingolipid and phosphatidylcholine. They all grow well at an optimum temperature of 25 °C, at pH 7. The draft genomes of strains BT552^T, BT553^T and KR1UV-12^T measures 4 035 561 bp, 3 941 714 bp and 3 418 792 bp, respectively, comprising 3 804 3648 and 3236 coding sequences and 50, 48 and 45 RNA genes. The average nucleotide identity analysis and digital DNA-DNA hybridization values between BT552^T, BT553^T and KR1UV-12^T and closely related <i>Sphingomonas</i> species range from 72.7 to 80.2% and 19.4 to 24.3%, respectively. Based on phenotypic, genotypic and chemotaxonomic data, these three strains BT552^T, BT553^T and KR1UV-12^T represent three novel bacterial species within the genus <i>Sphingomonas</i> for which the names <i>Sphingomonas longa</i> sp. nov. (type strain BT552^T= KCTC 82094^T =NBRC 114993^T), <i>Sphingomonas mollis</i> sp. nov. (type strain BT553^T =KCTC 82095^T =NBRC 114994^T) and <i>Sphingomonas aurea</i> sp. nov. (type strain KR1UV-12^T = KCTC 92959^T = TBRC 18506^T) are proposed.