Anoxic bioremediation of hydrocarbons

The contamination of soils and sediments by petroleum is a matter of international concern because of the toxicity and refractory character of the aromatic components in the absence of oxygen1. Gaseous oxygen can be injected into the anaerobic zone of a contaminated environment2 to stimulate biodegradation, but this is costly and inefficient. Other more soluble electron acceptors, such as nitrate or sulphate, can be used instead, but oxidation is slow and hydrocarbon degradation is incomplete3. Here we describe how chlorite dismutation by perchlorate-reducing bacteria can be used as an alternative source of oxygen for degrading contaminants. This dismutation of chlorite into molecular oxygen and chloride is an intermediate step in the microbial reduction of perchlorate or chlorate4.