Sphingomonas rustica sp. nov. and Sphingomonas agrestis sp. nov., novel carotenoid-producing bacterial species isolated from farm soil.

Abstract

Two yellow-pigmented novel strains, designated HF-S3T and HF-S4T, were isolated from farm soil in Paju, Republic of Korea. Cells of the two strains are characteristically Gram-stain-negative, facultatively anaerobic, catalase- and oxidase-positive, non-motile and rod-shaped. Strain HF-S3T grew at 10-37 °C, while HF-S4T grew at 15-35 °C. Both strains grew at pH 5.0-12.0 and in NaCl concentrations (w/v) of 0-2.0%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that HF-S3T and HF-S4T belong to the genus Sphingomonas, with HF-S3T exhibiting 97.7, 97.6 and 97.4% similarity to Sphingomonas cannabina DM2-R-LB4T, Sphingomonas leidyi DSM 4733T and Sphingomonas canadensis FWC47T, respectively. Strain HF-S4T displayed 97.9, 97.7 and 97.6% similarity to Sphingomonas psychrotolerans Cra20T, Sphingomonas gei ZFGT-11T and Sphingomonas naasensis KIS18-15T, respectively. The DNA G+C contents of HF-S3T and HF-S4T were 67.0 and 66.5 mol%, respectively. The digital DNA-DNA hybridization and average nucleotide identity values among the novel and related type strains were 20.2-28.2% and 75.9-84.3%, respectively. They all contained C14:0 2-OH and C16:0, summed feature 8 (C18:1 ω6c and/or C18:1 ω7c) as the major fatty acids and ubiquinone-10 as the predominant respiratory quinone. Strains HF-S3T and HF-S4T were found to produce carotenoid-type pigments. Based on polyphasic taxonomic analysis, the new isolates ostensibly represent two novel species of the genus Sphingomonas, with the proposed names Sphingomonas rustica sp. nov. and Sphingomonas agrestis sp. nov. for strains HF-S3T and HF-S4T, respectively. The S. rustica and S. agrestis type strains are HF-S3T (=KACC 23554T =TBRC 18352T) and HF-S4T (=KACC 23386T =TBRC 17899T), respectively.