[Effects of Rhizobium meliloti on PCBs degradation and transformation in solution culture].

The capability of Rhizobium meliloti on degrading 2,4,4'-trichlorobiphenyl and 18 kinds of polychlorinated biphenyl congener mixtures was studied by shaking flask experiment. The results showed that the degradation capability of Rhizobium meliloti to 2, 4, 4'-trichlorobiphenyl increased gradually with the increasing concentration of 2, 4, 4'-trichlorobiphenyl. After 7 days, the degradation rates of 2, 4, 4'-trichlorobiphenyl under 1.0, 5.0 10.0, 25.0, 50.0 mg x L(-1) concentration of 2, 4, 4'-trichlorobiphenyl were 34.0%, 48.3%, 69.7%, 96.0%, 98.5% respectively. Meanwhile some new intermediate products were found in the solution culture. The capability of Rhizobium meliloti on degrading 18 kinds of polychlorinated biphenyls congener mixtures appeared in a trend from low to high, then decreased to a certain balance with the increasing concentration of the mixture. The highest degradation rate was 54.7%, and moreover, a transformation process from higher chlorinated PCBs congeners to lower chlorinated PCBs congeners emerged.