Chlorophenols and other related derivatives of environmental concern: Properties, distribution and microbial degradation processes

Chlorophenols are chlorinated aromatic compound structures and are commonly found in pesticide preparations as well as industrial wastes. They are recalcitrant to biodegradation and consequently persistent in the environment. A variety of chlorophenols derivatives compounds are highly toxic, mutagenic and carcinogenic for living organisms. Biological transformation by microorganisms is one of the key remediation options that can be exploited to solve environmental pollution problems caused by these notorious compounds. The key enzymes in the microbial degradation of chlorophenols are the oxygenases and dioxygenases. These enzymes can be engineered for enhanced degradation of highly chlorinated aromatic compounds through directed evolution methods. This review underscores the mechanisms of chlorophenols biodegradation with the view to understanding how bioremediation processes can be optimized for cleaning up chloroaromatic contaminated environments.

► Properties, distribution and environmental fate of chlorophenols.
► Biodegradation and biotransformation of chlorophenols.
► Genetics of 2,4,6-trichlorophenol (2,4,6-TCP) degradation.
► The functional role of flavin reductase and quinone reductase in degradation.
► Evolution of genes involved in chlorophenol degradation in bacteria.