from Michel Sylvestre and Jean-Patrick Toussaint writing in Microbial Bioremediation of Non-metals: Current Research:
The fate of PCBs in soil and sediments is driven by a combination of interacting processes including several known biological processes. Under anaerobic conditions some bacteria use organohalides (including PCBs) as terminal acceptors. This process is responsible for the depletion of highly chlorinated congeners. Under aerobic conditions, PCBs are oxidized and mineralized by fungi through various pathways involving ligninolytic enzymes and monooxygenases and by bacteria through an initial dioxygenation reaction. Furthermore, several investigations have brought evidence that the rhizosphere provides a remarkable ecological niche to enhance the PCB degradation process by rhizobacteria. In this review, we will briefly summarize our current knowledge regarding the four above-mentioned biological processes involved in PCB degradation. Currently, the biochemistry of the anaerobic PCB-degrading process is still poorly understood. In the case of fungal enzymes, it is not yet clear which of the ligninolytic or monooxygenase systems prevails in PCB degradation. However, the bacterial oxidative enzymes have been investigated extensively. Furthermore, recent studies suggest that designing processes based on plant-microbe association are very promising avenues to remediate PCB-contaminated sites. In this review emphasis will be placed on the current state of knowledge regarding the strategies that are proposed to engineer PCB-degrading bacterial oxidative enzymes and PCB-degrading plant-microbe systems to degrade PCBs.
Further reading: Microbial Bioremediation of Non-metals: Current Research