Characterization and phylogenetic analysis of a phenanthrene-degrading strain isolated from oil-contaminated soil

Bacterium strain EVA17 was isolated from an oil-contaminated soil, and identified as Sphingomonas sp. based on analysis of 16S rDNA sequence,cellular fatty acid composition and physiological-chemical tests. The salicylate hydroxylase and catechol 2,3-dioxygenase(C23O) were detected in cell-free lysates, suggesting a pathway for phenanthrene catabolism via salicylate and catechol. Alignment showed that both of the C23O and GST genes of the strain EVA17 had high similarity with homologues of strains from genus Sphingomonas. The phylogenetic analysis based on 16S rDNA and C23O gene sequence indicated that EVA17 should be classified into genus Sphingomonas, although the two phylogenetic trees were slightly different from each other. The results of co-amplification and sequence determination indicated that GST gene should be located upstream of the C23O gene.