MICROBIAL-DEGRADATION OF BIPHENYL AND ITS DERIVATIVES

The role of microorganisms in maintaining steady-state concentrations of environmental chemicals is well established and these activities constitute the basis for the cycle of carbon in nature. However, the widespread, recalcitrant, and bioaccumulating nature of polychlorinated biphenyls (PCBs) presents a major environmental problem. Research to optimize the breakdown of PCBs has been directed firstly at the isolation of species especially competent in the removal of a spectrum of Aroclor components, and secondly, at the bringing together of pathway segments with a view to constructing an organism that can use PCBs as sole carbon source. Electron acceptors are usually limiting in anaerobic environments, so that a selection pressure is exerted by PCB contamination in river sediments. The microbial population adapts to the Aroclor present and to achieve optimal dehalogenation, one should look at sites contaminated by this mixture for suitable experimental inocula. Competition with existing microorganisms for space and nutrients is a limiting factor for all new inoculants, even for soil biphenyl degraders provided with biphenyl. © 1992, Academic Press Inc.