Yeast Breakthrough Boosts Ethanol?

Ethanol, it seems, is the fuel that only a politician from a farm state in the U.S. could love.

Ethanol, it seems, is the fuel that only a politician from a farm state in the U.S. could love. On the one hand there are those decrying the fact that food is being used for fuel—although that canard is going by the wayside as the sorts of things that are now being used to produce ethanol wouldn’t be palatable to a goat—and those who are maintaining that it is simply not economic, although these people probably don’t do the full accounting that a large dependence on foreign oil has on many countries, particularly the U.S.

Word out of the University of Illinois is that a new engineered yeast strain can boost ethanol output from plants. While it is as complex as you might imagine, given that the collaboration included the university as well as Lawrence Berkeley National Laboratory, the University of California, and BP, what it comes down to is that the yeast can simultaneously consume two types of sugar from plants to produce ethanol. Typically the yeast only consumes one sugar at a time and it doesn’t do a bang-up job on the second one.

There’s glucose, a easy-to-ferment six-carbon sugar and there’s xylose, a trickier five-carbon sugar. Xylose is found in things like plant stems and leaves.

S U of I researchers: Suk-Jin Ha (left), Yong-Su Jin (center) and Soo Rin Kim (right).  Photo by L. Brian Stauffer

Yong-Su Jin, a professor of food science and human nutrition at the U of I, an affiliate of the U of I Institute for Genomic Biology, and a principal investigator on the study told Diana Yates of the U of I News Bureau, “Xylose is a wood sugar, a five-carbon sugar that is very abundant in lignocellulosic biomass but on it our food.” He added, “Most yeast cannot ferment xylose.”

But the newly engineered yeast can.

As postdoc researcher and lead author of the study, Suk-Jin Ha told Yates, “If you do the fermentation using only cellobiose [a precursor of glucose] or xylose, it takes 48 hours. But if you do the co-fermentation with the cellobiose and xylose, double the amount of sugar is consumed in the same amount of time and produces more than double the amount of ethanol. It’s a huge synergistic effect of co-fermentation.”

Jin is quoted by Yates as saying, “We don’t have to do two separate fermentations. We can do it all in one pot. And the yield is even higher than the industry standard. We are pretty sure that this research can be commercialized very soon.”

Let’s face it: there are a lot of sticks and inedible leaves around, so. . . .