Anaerobic benzene oxidation coupled to nitrate reduction in pure culture by two strains of Dechloromonas

Benzene contamination is a significant problem. It is used in a wide range of manufacturing processes and is a primary component of petroleum-based fu els. Benzene is a hydrocarbon that is soluble, mobile, toxic and stable, es pecially in ground and surface waters. It is poorly biodegraded in the abse nce of oxygen. However, anaerobic benzene biodegradation has been documente d under various conditions. Although benzene biomineralization has been dem onstrated with nitrate(1), Fe(III)(2-5), sulphate(6,7) or CO28,9 as alterna tive electron acceptors, these studies were based on sediments or microbial enrichments. Until now there were no organisms in pure culture that degrad ed benzene anaerobically. Here we report two Dechloromonas strains, RCB and JJ, that can completely mineralize various mono-aromatic compounds includi ng benzene to CO2 in the absence of O-2 with nitrate as the electron accept or. This is the first example, to our knowledge, of an organism of any type that can oxidize benzene anaerobically, and we demonstrate the potential a pplicability of these organisms to the treatment of contaminated environmen ts.