[Isolation and degradation characteristics of PCB-degrading strain]

A new PCB-degrading bacterial strain named PS-11 was isolated from soil contaminated with PCBs by enrichment culture. The strain was identified as Stenotrophomonas maltophilia according to the results of the analyses of 16S rDNA sequence. It was observed that the degradation rate of PCB52 by strain PS-11 was 31.1% after 4 days and 52.9% after 7 days in cultures containing 2 mg x L(-1) PCB52. The degradation rate was 10.9% for 2 mg x L(-1) refractory PCB153 after 7 days. In addition, the strain showed very good environmental tolerance. It could grow and degrade PCB52 in the culture medium at 30 degrees C and pH 7-9 with PCB52 concentrations of 2-10 mg x L(-1), especially, pH 7 and 2 mg x L(-1) PCB52 was found to be the best condition for cell growth and degradation. The growth of strain PS-11 was affected by different carbon sources. The strain showed best growth when sucrose was used as carbon source and the shortest lag time was observed when glucose was used as carbon source. In addition, sucrose, glucose and Tween-80 could increase the degradation rate of PCB52 by PS-11. Further study showed that the strain PS-11 could resist some heavy metal ions at high concentrations, the tolerance in a descending order was: Pb2+ > Cd2+ > Zn2+ > Cu2+.