Novosphingobium olei sp. nov., with the ability to degrade diesel oil, isolated from oil-contaminated soil and proposal to reclassify Novosphingobium stygium as a later heterotypic synonym of Novosphingobium aromaticivorans

Abstract

Two yellow-pigmented, non-motile, Gram-stain-negative, and rod-shaped bacteria, designated TW-4^T and TNP-2 were obtained from oil-contaminated soil. Both strains degrade diesel oil, hydrolyse aesculin, DNA, Tween 40 and Tween 60. A phylogenetic analysis based on its 16S rRNA gene sequence revealed that strain TW-4^T formed a lineage within the family Erythrobacteraceae and clustered as members of the genus Novosphingobium. The closest members of strain TW-4^T were Novosphingobium subterraneum DSM 12447^T (97.9 %, sequence similarity), Novosphingobium lubricantis KSS165-70^T (97.8 %), Novosphingobium taihuense T3-B9^T (97.8 %), Novosphingobium aromaticivorans DSM 12444^T (97.7 %), Novosphingobium flavum UCT-28^T (97.7 %), and Novosphingobium bradum STM-24^T (97.6 %). The sequence similarity for other members was ≤97.6 %. The genome of strain TW-4^T was 4 683 467 bp long with 44 scaffolds and 4280 protein-coding genes. The sole respiratory quinone was Q-10. The major cellular fatty acids were summed feature 8 (C_{18 : 1} ω7c and/or C_{18 : 1} ω6c), summed feature 3 (C_{16 : 1} ω7c and/or C_{16 : 1} ω6c), C_{16 : 0} and C_{14 : 0} 2-OH. The major polar lipids were phosphatidylethanolamine (PE), phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), phosphatidylcholine (PC), phosphatidyl-n-methylethanolamine (PME) and sphingoglycolipid (SGL). The DNA G+C content of the type strain was 65.0 %. The average nucleotide identity (ANIu) and in silico DNA-DNA hybridization (dDDH) relatedness values between strain TW-4^T and closest members were below the threshold value for species delineation. Based on polyphasic taxonomic analyses, strain TW-4^T represents novel species in the genus Novosphingobium, for which the name Novosphingobium olei sp. nov. is proposed. The type strain is TW-4^T (=KACC 21628^T=NBRC 114364^T) and strain TNP-2 (=KACC 21629=NBRC 114365) represents an additional strain. Based on new data obtained in this study, it is also proposed to reclassify Novosphingobium stygium as a later heterotypic synonym of Novosphingobium aromaticivorans.

Keywords: Diesel degradation; Erythrobacteraceae; Novosphingobium olei; Oil-contaminated soil; Proteobacteria.