Isolation and characterization of a toxic metal-tolerant Phenanthrene-degrader Sphingobium sp. in a two-liquid-phase partitioning bioreactor (TPPB)

A phenanthrene-degrading strain PHE3, identified as the genus of Sphingobium, was isolated using a two-liquid-phase partitioning bioreactor. More than 96 % of the initial amount (up to 100 mg l⁻¹ silicone oil) of phenanthrene was removed within 77 h by PHE3. Degradation of phenanthrene by PHE3 at pH 7 was also observed in the presence of Cu (II), Zn (II) and Cd (II) ions. Cu (II) showed the highest toxicity to PHE3, followed by Cd (II) and Zn (II). Tolerance to Cu (II) by PHE3 was up to 20 mg l⁻¹ in terms of total aqueous concentration, and up to 40 mg l⁻¹ for both Zn and Cd. Interestingly, 20 mg l⁻¹ of Zn (II) stimulated phenanthrene degradation after 20 h incubation. Its high tolerance to toxic metals and phenanthrene degradation ability of PHE3 highlights its significance in the study of microbial remediation in soils co-polluted by PAHs and metals.