Jianjun Shuai

Regional analysis of potential polychlorinated biphenyl degrading bacterial strains from China

Polychlorinated biphenyls (PCBs), the chlorinated derivatives of biphenyl, are one of the most prevalent, highly toxic and persistent groups of contaminants in the environment. The objective of this study was to investigate the biodegradation of PCBs in northeastern (Heilongjiang Province), northern (Shanxi Province) and eastern China (Shanghai municipality). From these areas, nine soil samples were screened for PCB-degrading bacteria using a functional complementarity method. The genomic 16S rDNA locus was amplified and the products were sequenced to identify the bacterial genera. Seven Pseudomonas strains were selected to compare the capacity of bacteria from different regions to degrade biphenyl by HPLC. Compared to the biphenyl content in controls of 100%, the biphenyl content went down to 3.7% for strain P9-324, 36.3% for P2-11, and 20.0% for the other five strains. These results indicate that a longer processing time led to more degradation of biphenyl. PCB-degrading bacterial strains are distributed differently in different regions of China.

Expression and characterization of a recombinant 2,3-dihydroxybiphenyl-1,2-dioxygenase from Pseudomonas

The 2, 3-dihydroxybiphenyl-1,2-dioxygenase, which can degrade the 2,3-dihydroxybiphenyl, was encoded by a synthesized PsbphCI gene. The PsbphCI gene was transformed into Escherichia coli and the encoding protein purified, had a molecular mass of ∼32 kDa as determined by SDS-PAGE. The optimum pH for the purified enzyme at 20°C was 9.0, and the optimal temperature at pH 8.0 was 30°C. Subsequently, the PsbphCI gene was transformed into Pseudomonas putida sp. to verify the degradation of 2,3-dihydroxybiphenyl by HPLC. The transgenic EG11 strain degraded 65.20% of the 2,3-DHBP after 2 minutes at 30°C, while the wild-type EG11 strain degraded only 37.75%. This study provides guidance for the cultivation of bioengineered biphenyl/PCBs-degrading bacteria which can be applied to the biodegradation of environmental biphenyl/PCBs contamination.