Novosphingobium panipatense sp nov and Novosphingobium mathurense sp nov., from oil-contaminated soil

In an ongoing attempt to analyse the diversity of culturable micro-organisms from oil-contaminated soil, two yellow-pigmented, Gram-negative, halophilic bacterial strains (SM16(T) and SM117(T)) were isolated. These two strains were characterized using a polyphasic approach. Strains SM16(T) and SM117(T) showed a range of phenotypic and chemotaxonomic properties that were consistent with those of members of the genus Novosphingobium. Both strains contained sphingoglycolipids, thus confirming that they belong to the Alphaproteobacteria. Furthermore, the polar lipid profile consisted of phosphatidylglycerol, phosphatidyldimethylethanolamine and phosphatidylethanolamine, with minor amounts of phosphatidyldimethylethanolamine, phosphatidylcholine and phosphatidylmonomethylethanolamine. Spermidine was the major polyamine in the cell wall, a characteristic feature of members of the genus Novosphingobium. Fatty acid analysis revealed the presence of C-18:(1)omega 7c, C-16:0 and C-14:0 2-OH in both isolates, a characteristic feature of sphingomonads. 16S rRNA gene sequence similarities with the type strains of the most closely related species of the genus Novosphingobium (Novosphingobium pentaromativorans and Novosphingobium resinovorum) were less than 98.8% for both strains. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strains SM16(T) and SM117(T) fall in the clade represented by the genus Novosphingobium. Strains SM16(T) and SM117(T) shared 98.8 % similarity in their 16S rRNA gene sequences and their mean level of DNA-DNA relatedness was 8.5%. Strains SM16(T) and SM117(T) differed from each other with respect to their morphological, physiological and chemotaxonomic properties. Thus, these results indicate that strains SM16(T) and SM117(T) belong to separate species of the genus Novosphingobium, for which the names Novosphingobium panipatense sp. nov. and Novosphingobium mathurense sp. nov. are proposed; the type strains are SM16(T) (=CCM 7472(T) =MTCC9019(T)) and SM117(T) (=CCM 7473(T) =MTCC9020(T)), respectively.