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Bacteria produce fuel

Christopher Brigham / MIT

Group of Ralstonia eutropha bacteria in culture medium: producing isobutanolChristopher Brigham / MIT

Genetic alterations in Ralstonia eutropha by researchers at the Massachusetts Institute of Technology (MIT) have turned this bacterium into a producer of isobutanol, a type of alcohol similar to gasoline and that can be used as fuel. To do this, R. eutropha consumes carbon dioxide (CO2) and other materials, such as sugars, organic acids, and fats. “The modified bacterium does double duty, cleaning the environment and producing fuel,” says Christopher Brigham, one of the researchers at MIT. R. eutropha is known to science for producing the bioplastic polyhydroxybutyrate (PHB) when under nutritional stress and when excess carbon is present. In order to get R. eutropha to produce isobutanol, the bioplastic-producing genes had to be removed from its genome. After that, one of the mutant strains produced 150 milligrams of isobutanol per liter of bacterial culture. After making some additional changes in the bacterium’s enzyme production, the MIT researchers successfully obtained a yield of 14 grams of isobutanol per liter after growing the bacterial culture for 50 days. “Our work was proof of concept. We were able to alter the bacterium so as to produce isobutanol,” says Brazilian agronomist Claudia Santos Gai, who has undergraduate and doctoral degrees from the University of São Paulo (USP) and is now a post-doctoral student at MIT.