Characterization of Biodegradation of Phenanthrene and Other Aromatic Substrates by Sphingomonas sp. GY2B

The characterization of Sphingomonas sp. GY2B degrading phenanthrene and other substrates was described in this study. Phenanthrene was nearly degraded completely by strain GY2B at initial concentration of 10 and 60 mg·L-1 after 24 and 60 hours inoculation, respectively. While only about 70% phenanthrene was degraded after 48 hours inoculation at initial concentration of 230 mg·L-1, and a lot of phenanthrene still remained in the medium after 120 hours inoculation. Further UV-Vis analysis showed a great deal 1-hydroxy-2-naphthoic acid was accumulated in the culture at highly initial concentration of phenanthrene. At the same time no significant correlation between initial phenanthrene concentration and microbial specific growth rate μ was observed. In addition, 2-hydroxymuconic semial-dehyde as an intermediate in the degradation process of salicylic acid, 1-hydroxy-2-naphthoic acid, and naphthalene by strain GY2B, was found in the process of phenanthrene degradation through the UV-Vis analysis, which clearly suggested the degradation pathway of phenanthrene: under oxygenase of strain Sphingomonas sp. GY2B, phenanthrene was degraded via salicylate pathway and catechol meta-cleavage pathway to form 2-hydroxymuconic semial-dehyde.