University of California, Berkeley, chemists have engineered bacteria to churn out a gasoline-like biofuel at about 10 times the rate of competing microbes, a breakthrough that could soon provide an affordable and "green" transportation fuel.
The development is reported online this week in advance of publication in the journal Nature Chemical Biology by Michelle C. Y. Chang, assistant professor of chemistry at UC Berkeley, graduate student Brooks B. Bond-Watts and recent UC Berkeley graduate Robert J. Bellerose.
Various species of the Clostridium bacteria naturally produce a chemical called n-butanol (normal butanol) that has been proposed as a substitute for diesel oil and gasoline. While most researchers, including a few biofuel companies, have genetically altered Clostridium to boost its ability to produce n-butanol, others have plucked enzymes from the bacteria and inserted them into other microbes, such as yeast, to turn them into n-butanol factories. Yeast and E. coli, one of the main bacteria in the human gut, are considered to be easier to grow on an industrial scale.
While these techniques have produced promising genetically altered E. coli bacteria and yeast, n-butanol production has been limited to little more than half a gram per liter, far below the amounts needed for affordable production.
Chang and her colleagues stuck the same enzyme pathway into E. coli, but replaced two of the five enzymes with look-alikes from other organisms that avoided one of the problems other researchers have had: n-butanol being converted back into its chemical precursors by the same enzymes that produce it.
The new genetically altered E. coli produced nearly five grams of n-buranol per liter, about the same as the native Clostridium and one-third the production of the best genetically altered Clostridium, but about 10 times better than current industrial micr
|Contact: Robert Sanders|
University of California - Berkeley