Anaerobic microbial degradation of organic pollutants with chlorate as electron acceptor.

Aliphatic and aromatic hydrocarbons are two groups of compounds that are widespread pollutants. The aerobic microbial degradation of aliphatic and aromatic hydrocarbons proceeds in general fast and has been widely studied, while the biodegradation in anoxic environments is often incomplete, proceeds at lower rates and is less characterized. Chlorate reduction is a unique process, which yields molecular oxygen upon microbial reduction in anoxic environments. This can be of practical importance, since the oxygen released can be incorporated into the anaerobically recalcitrant compounds by oxygenases to form hydroxylated derivatives, which can be further degraded easily either aerobically or anaerobically. We have found that Pseudomonas chloritidismutans AW-1T, which is a known chlorate-reducing bacterium, can combine the oxidation of n-alkanes and the reduction of chlorate. Similarly this bacterium can combine the degradation of benzoate and catechol with chlorate reduction. We studied the physiological and biochemical properties of this bacterium. With the help of proteogenomics we annotated the key proteins involved in alkane and benzoate oxidation with chlorate. Our findings suggest that oxygen released during chlorate reduction can be used to degrade the anaerobically recalcitrant compounds and chlorate reduction has a very high potential for bioremediation of anoxic soils.