Research - Category III: Water Quality

Feasibility of Using Bioaugmentation with Bacterial Strain PM 1 for Bioremediation of MTBE-Contaminated Vadose and Ground Water Environments
(Funded 1999-2000)

Principal Investigator: Kate M. Scow
Department of Land, Air, and Water Resources
UC Davis
(530) 752-4632
kmscow@ucdavis.edu

William R. Horwath
Department of Land, Air, and Water Resources
UC, Davis
(530) 752-6029
wrhorwath@ucdavis.edu

Executive Summary:
The fuel additive, methyl tertiary-butyl ether (MTBE), has become a widespread environmental contaminant in the past decade. Since MTBE was introduced to gasoline as an additive in 1988, its production has increased to 14 billion pounds per year and currently comprises up to 15% of some reformulated gasoline (Kirschner 1995). This increased usage coupled with high incidences of leaking underground storage tanks has led to MTBE contamination of ground water, soils, and sediments. There is little evidence that extensive intrinsic remediation is occurring at MTBE contaminated sites. Thus it is important to explore the potential of using active bioremediation, a potentially promising technology for inexpensive treatment of MTBE contaminated ground water Many challenges must be overcome before bioremediation of MTBE can be successfully implemented at the field scale, including the identification and culturing of an MTBE-degrading inoculant, the engineering constraints associated with in situ, and insurance of inoculant survival and activity in contaminated environments. Our laboratory has recently isolated a bacterial culture, Strain PM 1, which is capable of using MTBE as its sole carbon and energy source at relatively rapid rates. In addition, a preliminary study indicates that the organism can also degrade MTBE when inoculated into a soil microcosm.

The objectives of this study are to measure the potential for and rates of biodegradation of MTBE in contaminated and MTBE-spiked uncontaminated vadose and groundwater materials inoculated with Strain PM 1. We will also measure the survival of Strain PM 1 when it is inoculated into environmental samples and bioreactors. In order to more fully optimize conditions for use of Strain PM 1 as an inoculant we will continue to characterize the physiology of the bacterial strain with regard to nutrient and growth factor requirements, MTBE kinetic parameters, MTBE concentration range, maintenance of MTBE degrading activity, and starvation survival. Finally we will characterize the metabolic pathway of MTBE degradation by Strain PM 1.

Predicted results and benefits of this study will be information about the feasibility of using Strain PM 1 in bioremediation of MTBE-contaminated subsurface environments and in bioreactors. This study will also increase our basic understanding of the physiology and metabolic activity of Strain PM 1 that can, in turn, be used to optimize bioremediation technologies involving Strain PM 1.