Researchers Take Major Step To Effective ‘Bio-gasoline’

Most people probably don’t fit “bio” and “gasoline” into the same sentence, much less the same word. Nor would they likely include “sustainable.”

Yet we have ethanol, essentially a renewable analogue of gasoline made from corn. It has a drawback, though, in that it shunts too much corn from the table to the gas tank, driving up the cost of a food staple for billions of people and livestock.

But there’s another kind of “bio-gasoline,” formally known as isopentenol, but so far producing sufficient amounts has been elusive until now, according to Aindrila Mukhopadhyay, the director of host engineering at the Joint BioEnergy Institute (JBEI) in Emeryville, Calif.

Mukhopadhyay said several groups of researchers have used the common gut bacterium Escherichia coli, better known as E. coli, to produce alcohol solvents including isopentenol. But so far they’ve been stymied because the solvent being created by the bacteria was killing the bacteria, aborting the process and any hopes of producing “bio-gasoline” on an industrial level.

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So Mukhopadhyay and her team took what she calld “a systems biology approach: Could we engineer bacteria to also tolerate the solvent it is producing?” She could, and did. Her research is published in mBio, the online open-access journal of the American Society for Microbiology.

First Mukhopadhyay enlisted the help of scientists from Nanyang Technological University in Singapore, the National University of Singapore and the University of California at Berkeley. Together they isolated a strain of E. coli that wasn’t producing isopentenol, exposed it to isopentenol produced elsewhere, then examined which of the bacterium’s genes showed changes indicating resistance to the solvent.

The researchers selected 40 of these genes and added them to a strain of E. coli that was producing isopentenol in order to learn which genes might strengthen the bacterium. Two of them looked promising: MetR, which improved isopentenol production by 55 percent, and MdlB, which improved production by 12 percent.

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They also learned that by increasing a protein within the MdlB, the production of isopentenol improved up to 60 percent compared to the E. coli with the unenhanced strain of MdlB.

Mukhopadhyay said this method was encouraging because, basically, it forces the bacteria-destroying solvent out of the cell and could separate the way oil and water do, with the “bio-gasoline” floating in a distinct layer above the water-like fluid where the bacteria live.

If all her research pans out, Mukhopadhyay said, sustainable, clean “bio-gasoline” could provide quick access to renewable fuels that would lessen automotive emissions of greenhouse gases. “Biofuels are one tool in the array of alternative energy solutions that can be used in our infrastructure immediately,” she said.

By Andy Tully of Oilprice.com

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