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, BT552T, BT553T and KR1UV- 12T, 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 BT552T, BT553T and KR1UV- 12T clustered to a distinct clade within the family Sphingomonadaceae (order Sphingomonadales, class Alphaproteobacteria). The strains exhibited the highest genetic similarity with representatives of the genus Sphingomonas; moreover, strains BT552T and BT553T tightly clustered with Sphingomonas melonis DAPP- PG 224T (98.2 and 98.1 %) and Sphingomonas aquatilis JSS-7T (98.1 and 98.0 %), while strain KR1UV- 12T clustered with S. melonis DAPP- PG 224T (97.9%) and Sphingomonas rubra BH3T (97.8%), respectively. The major cellular fatty acids of all three strains were summed feature 8 (C18:1 omega 7c/C18:1 omega 6c), 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 degrees C, at pH 7. The draft genomes of strains BT552T, BT553T and KR1UV- 12T 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 BT552T, BT553T and KR1UV- 12T and closely related Sphingomonas 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 BT552T, BT553T and KR1UV- 12T represent three novel bacterial species within the genus Sphingomonas for which the names Sphingomonas longa sp. nov. (type strain BT552T= KCTC 82094T =NBRC 114993T), Sphingomonas mollis sp. nov. (type strain BT553T =KCTC 82095T =NBRC 114994T) and Sphingomonas aurea sp. nov. (type strain KR1UV- 12T = KCTC 92959T = TBRC 18506T) are proposed.