Microbes for Groundwater MTBE

• The Häggblom laboratory
• More information on MTBE from U.S. Dept. of Energy
  

Max Häggblom’s Rutgers laboratory has taken an important step on the path to using microbes to rid the environment of methyl tertiary-butyl ether (MTBE), a toxic gasoline additive classified as a potential human carcinogen. It 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 Rutgers’ department of biochemistry and microbiology and the Biotechnology Center for Agriculture and the Environment on Rutgers’ Cook College campus. “MTBE is slowly being banned, but it’s going to stay in our groundwater for centuries,” he said.

Since MTBE contamination is underground, anaerobic bacteria – those that operate in the absence of oxygen – are the most likely candidates for the cleanup job. Häggblom and his team have a way to facilitate their 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.”

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.