This Small Business Innovation Research (SBIR) Phase II Project is designed to develop and demonstrate a new in situ treatment technology for the destruction of methyl tert-butyl ether (MTBE) in groundwater. The gasoline additive MTBE is the second most prevalent groundwater contaminant in the United States, and there are currently no economical technologies for its removal from the water supply. This technology utilizes a novel bacterium of the species Hydrogenophaga flava (ENV735) for the remediation of MTBE. This bacterium, which was recently isolated by Envirogen scientists, is one of only two bacterial strains discovered that are capable of growth on MTBE. Phase II experiments will be conducted to: (1) assess the movement and distribution of the bacterium in the subsurface; (2) develop an adhesion-deficient strain for improved aquifer distribution; and (3) optimize commercial-scale growth, shipment, and injection of the bacterium for field application. A field demonstration will be conducted to fully test the technology under in situ conditions. <br/><br/>The bioaugmentation with ENV735 has broad potential as an in situ remediation technology for MTBE-contaminated aquifers. If the results of the field trial are positive, commercialization of the bioaugmentation technology is anticipated in the short term.