Aerobic Degradation of Chloroaromatics

Microorganisms are key players in the global carbon cycle. In addition, it appears that most xenobiotic industrial chemicals can be degraded by microorganisms, either by a combination of cometabolic steps or by serving as growth substrate, leading to the mineralization of at least part of the molecule. Here, we present the principles of the microbial aerobic degradation of chloroaromatic compounds. The so-called peripheral sequences of the oxidative degradation of chloroaromatic compounds in aerobic bacteria yield central intermediates with a diphenolic structure such as catechols or hydroxybenzoquinols. These compounds are subsequently cleaved by enzymes that use molecular oxygen and further metabolized by central pathway sequences. The broad variety of mechanisms resulting in dechlorination that occur in these peripheral or central sequences is specifically discussed.