The UC Davis Superfund Research Program team has isolated a robust, naturally occurring microorganism, Methylibium petroleiphilum PM1, determined its genome sequence and developed a rapid, real-time PCR-based bioassay that can be used to supplement classical monitoring technologies at sites contaminated with methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (TBA). Quantitative spatial and temporal enumeration of strain PM1 correlates with MTBE and TBA contamination and provides evidence for bioremediation potential.
They tested the capacity of uninoculated, field-scale bioreactors for MTBE degradation at two locations: in a North Hollywood, CA aquifer and in a contaminated drinking water aquifer at Glennville, CA. The GAC bioreactor in North Hollywood was rapidly colonized by native bacteria, while inoculation with mixed MTBE degrading culture was necessary in the Glennville bioreactor. Both systems efficiently biodegraded MTBE and TBA. Quantitative PCR was used to enumerate total bacterial counts and sequences of the PM1 MTBE-degrading bacteria.
To determine which technologies were necessary for safe drinking water production, they assessed the presence and behavior of ten potential waterborne pathogens, total coliforms and heterotrophic plate count (HPC) numbers across the Glennville bioreactor. In most cases potentially pathogenic microorganisms were either not detected or their numbers decreased across the bioreactor. Total bacteria enumerated by HPC also decreased across the bioreactor. This work demonstrated that bioreactors are capable of sustaining high densities of MTBE-degrading bacteria and rapid degradation of MTBE and TBA. The GAC and fluidized bed bioreactors are being tested at additional field sites, and transferred to a new partnership of end users, including community members, regulatory agencies and the drinking water industry.
This research was conducted under the NIEHS Superfund Research Program (SRP) and will be presented by Dr. Krassimira R. Hristova.