Microbial Degradation of Polychlorophenols

Abstract

Polychlorophenols are major environmental pollutants, and their degradation by microorganisms has been extensively studied for the purpose of bioremediation. Three different metabolic pathways for aerobic degradation of polychlorophenols have been completely worked out, revealing the metabolic diversity for these structurally similar compounds. Substituted quinols, rather than catechols, are key metabolic intermediates of polychlorophenol biodegradation. Substituted quinols and quinones are also called as p–hydroquinones and p-benzoquinones, reflecting the reduced and oxidized forms. For example, tetrachloroquinol is the same as tetrachloro-p-hydroquinone, and tetrachloroquinone is often referred as tetrachloro-p-benzoquinone. Characterization of individual enzymes has led to the discoveries of novel dechlorination mechanisms. The genes coding for the enzymes have been cloned and sequenced, and the gene organization and regulation suggest that recent gene recruitments have occurred for the degradation of some polychlorophenols.