Biodegradation of methyl tertiary-butyl ether (MTBE) and other fuel oxygenates

Methyl tertiary-butyl ether (MTBE) has been added to gasoline in the U.S. f or the last decade in order to meet the mandates of the 1990 Clean Air Act. This law decreed that gasoline sold in many locations must contain oxygena tes to improve combustion and minimize air pollution. Unfortunately, this w idespread use has led to the contamination of some soils and aquifers, and remediation is now required. Bioremediation has proven to be an environment ally responsible and cost-effective approach to remediating petroleum spill s; this article reviews the potential that bioremediation may also be appro priate for remediating MTBE contamination. There is now good evidence that MTBE can be degraded by bacteria and fungi under aerobic conditions, and pr omising indications that the process also occurs under methanogenic and fer ric iron-reducing conditions. Yet, apparently it is not a widespread phenom enon. The challenge is to find effective bioremediation strategies that max imize this biodegradation so that it can be used reliably in cleaning conta minated sites. Both simple biostimulation and more complex bioaugmentation protocols are being developed to meet this pressing need.