Knock on Wood

Altered trees might overcome a major barrier to renewable fuels.

In the search for new renewable fuels, more than a few good ideas have gotten stuck on lignin. A tough, glue-like substance found in the walls of plant cells, lignin creates a sticky web that ensnares energy-rich sugars such as cellulose, making them harder to extract and convert into usable energy. If it weren’t for lignin getting in the way, we might already be seeing ethanol from grasses and trees entering the market.

But CALS biochemist John Ralph PhD’82 may have found a way around the lignin problem: If we can’t beat lignin, why not change it?

Ralph’s lab team has figured out how to alter lignin so that it essentially unzips itself when exposed to mild chemicals, making more of a plant’s sugars available for extraction. Plants and trees grown with this altered form of lignin might not require expensive chemical treatments before conversion into ethanol, which could eliminate one of the most cost-prohibitive steps in the production of cellulosic ethanol.

“We are trying to redesign an agricultural plant so that its lignin falls apart easier to make the production of ethanol much more efficient,” says Ralph. “If we get this figured out, there is the potential for a huge reduction in the cost of ethanol.”

Ralph’s approach is so promising that it landed his scientific team at the center of a bidding war. A native of New Zealand who has studied lignin since he was 18, Ralph spent the past 20 years working as a scientist with the U.S. Dairy Forage Research Center on UW-Madison’s campus. When the U.S. Department of Energy announced a nearly half-billion dollar research effort to overcome the obstacles to cellulosic ethanol, he found his lignin expertise in serious demand. In the past year, he and his team received lucrative job offers from all three DOE-funded bioenergy research centers, including UW-Madison’s Great Lakes Bioenergy Research Center.

“People with John’s training, experience and creativity just do not exist in this country or elsewhere in the world,” says Tim Donohue, director of the GLBRC. “It was critical to get John’s research team plugged into the Wisconsin bioenergy effort.”

While he opted to stay in Madison, Ralph’s decision did put him on the move. He and his lab joined the biochemistry department so that he can now work full-time on unsticking the lignin problem. The group is already collaborating with a South Carolina biotechnology company called ArborGen to test its lab-altered lignin, with a goal of testing fast-growing poplar trees as a feedstock for the cellulosic ethanol industry.