Laboratory Announces Advancement In Microbial Approach For Addressing MTBE Contamination In Groundwater

Researchers with Rutgers, the State University of New Jersey, announced on March 22 they have taken an important step on the path to using microbes to rid the environment of the gasoline additive methyl tertiary-butyl ether (MTBE).

In a February 2006 paper in Applied and Environmental Microbiology, researchers with Max Häggblom's Rutgers laboratory bring to light a tool that will help them find the key bacteria capable of breaking down MTBE. The additive has contaminated virtually all groundwater in the United States through fuel spills and leaking underground gasoline storage tanks.

"While gasoline hydrocarbons are much more toxic than MTBE, they are just candy to microbes and don't become as persistent a problem," said Häggblom, a professor in the department of biochemistry and microbiology at Rutgers.

Since MTBE contamination is underground, anaerobic bacteria -- those that operate in the absence of oxygen -- are the most likely candidates for the cleanup job, the researchers say. The journal article discusses a way to facilitate the bacteria's use by employing carbon isotope fractionation: the changes in the isotopic ratios of carbon (its different molecular versions, carbon-12 and carbon-13) brought about from the selective degradation of the carbon-12 form in the case of MBTE.

"So when the ratio of carbon-12 to carbon-13 decreases, it indicates the presence of the kind of bacteria we are looking for," Häggblom said. "This approach also will help us eventually home in on precisely which bacterium is doing the eating -- possibly the best choice for large-scale underground applications."

Häggblom and his coworkers are characterizing the community of bacteria feeding on MTBE in their cultures and, based on initial analyses, there appear to be a dozen or so players. It is still unclear if just one bacterium or several are doing the job; perhaps one or more of them may just be feeding on the waste products of the main degrader or degraders. But Rutgers researchers are getting closer to answering these questions, and thereby making the anaerobes a practical solution to remediation of MTBE contaminated groundwater.

While the methodology is a step in the right direction, Häggblom remains concerned about the slow pace at which the anaerobes seem to operate as they break down MTBE, a feature of the microbes he observed in his laboratory. Only after the first three years of their 10-year study could Häggblom and his group discern that a microbe was feeding on the MTBE in his cultures. This snail-like pace is a serious obstacle, but once again, Häggblom and company may have a solution.

"We are trying some tricks to actually speed it up, one of which is adding a relatively innocuous natural substance that appears to stimulate the process," Hägglom said. The researchers are in the midst of applying for a patent on the technique.

Häggblom Laboratory:

This article originally appeared in the 03/01/2006 issue of Environmental Protection.

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