Sphingomonas aerophila sp. nov. and Sphingomonas naasensis sp. nov., isolated from air and soil, respectively.

Two strains, designated 5413J-26(T) and KIS18-15(T), were isolated from the air and forest soil, respectively, in South Korea. Cells of the two strains were Gram-stain-negative, aerobic, polar-flagellated and rod-shaped. According to the phylogenetic tree, strains 5413J-26(T) and KIS18-15(T) fell into the cluster of Sphingomonas sensu stricto. Strain 5413J-26(T) showed the highest sequence similarities with Sphingomonas trueperi LMG 2142(T) (96.6%), Sphingomonas molluscorum KMM 3882(T) (96.5%), Sphingomonas azotifigens NBRC 15497(T) (96.3 %) and Sphingomonas pituitosa EDIV(T) (96.1 %), while strain KIS18-15(T) had the highest sequence similarity with Sphingomonas soli T5-04(T) (96.8%), Sphingomonas pituitosa EDIV(T) (96.6%), Sphingomonas leidyi ATCC 15260(T) (96.6 %), Sphingomonas asaccharolytica NBRC 15499(T) (96.6 %) and Sphingomonas koreensis JSS26(T) (96.6 %). The 16S rRNA gene sequence similarity between strains 5413J-26(T) and KIS18-15(T) was 95.4 %. Ubiquinone 10 was the predominant respiratory quinone and homospermidine was the major polyamine. The major polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and several unidentified phospholipids and lipids. The main cellular fatty acids (>10% of the total fatty acids) of strain 5413J-26(T) were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c), summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH) and C14 : 0 2-OH, and those of strain KIS18-15(T) were summed feature 8 and C16 : 0. Based on the results of 16S rRNA gene sequence analysis, and physiological and biochemical characterization, two novel species with the suggested names Sphingomonas aerophila sp. nov. (type strain 5413J-26(T) = KACC 16533(T) = NBRC 108942(T)) and Sphingomonas naasensis sp. nov. (type strain KIS18-15(T) = KACC 16534(T) = NBRC 108943(T)) are proposed.