Sphingomonas abietis sp. nov., an Endophytic Bacterium Isolated from Korean Fir

PAMB 00755(T), a bacterial strain, was isolated from Korean fir leaves. The strain exhibits yellow colonies and consists of Gram-negative, non-motile, short rods or ovoid-shaped cells. It displays optimal growth conditions at 20°C, 0% NaCl, and pH 6.0. Results of 16S rRNA gene-based phylogenetic analyses showed that strain PAMB 00755(T) was most closely related to Sphingomonas chungangi MAH-6(T) (97.7%) and Sphingomonas polyaromaticivorans B2-7(T) (97.4%), and ≤96.5% sequence similarity to other members of the genus Sphingomonas. The values of average nucleotide identity (79.9–81.3%), average amino acid identity (73.3–75.9%), and digital DNA–DNA hybridization (73.3–75.9%) were significantly lower than the threshold values for species boundaries; these overall genome-related indexes (OGRI) analyses indicated that the strain represents a novel species. Genomic analysis revealed that the strain has a 4.4-Mbp genome encoding 4,083 functional genes, while the DNA G+C content of the whole genome is 66.1%. The genome of strain PAMB 00755(T) showed a putative carotenoid biosynthetic cluster responsible for its antioxidant activity. The respiratory quinone was identified as ubiquinone 10 (Q-10), while the major fatty acids in the profile were identified as C(18:1)ω7c and/or C(18:1)ω6c (summed feature 8). The major polar lipids of strain PAMB 00755(T) were diphosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid, and phosphatidylcholine. Based on a comprehensive analysis of genomic, phenotypic, and chemotaxonomic characteristics, we proposed the name Sphingomonas abietis sp. nov. for this novel species, with PAMB 00755(T) as the type strain (= KCTC 92781(T) = GDMCC 1.3779(T)).