Wood, straw and other plants are an excellent source of sugar that can be fermented to make ethanol, but extracting it is difficult because the biomass is so tough. Researchers in the UK think they have a solution to that problem that could boost the biofuel's viability.

The team, based at the University of Cambridge and part of the BBSRC Sustainable Bioenergy Centre, has discovered two enzymes that toughen wood, straw and plant stalks. By identifying and studying the genes of those enzymes, they've raised the possibility of breeding non-edible plants that require less processing, less energy and fewer chemicals to refine into biofuel.

"There is a lot of energy stored in wood and straw in the form of a substance called lignocellulose," lead researcher Prof. Paul Dupree said in a statement. "We wanted to find ways of making it easier to get at this energy and extract it in the form of sugars that can be fermented to produce bioethanol and other products."

Lignocellulose gives plants their strength and rigidity. Xylan is a key component of lignocellulose and represents about one-third of the sugars that could be used to make bioethanol. Releasing that energy would be a significant step forward because it would allow sustainable production of fuel without adversely impacting the food chain, the researchers said.

The team studied Arabidopsis plants that lack two enzymes in xylan. Although the stems of those plants were somewhat weaker than normal, they grow normally. They also tested how easily they could extract sugars from those plants and found it easier to convert all of the xylan to sugar.

"What we didn't want to do was end up with floppy plants that can't grow properly, so it was important to find a way of making xylan easier to break down without having any major effects," Dupree said.

The next step, Dupree said, is to breed feedstocks like willow and miscanthus with those properties.

"We expect to work closely with industrial collaborators to see how we can quickly transfer this research into real applications for transport fuels," he said.

Photo: TheFriendlyFiend / Flickr

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