DOE researchers engineer plant to give up sugar more easily

Source: Katherine Ling, E&E reporter • Posted: Tuesday, April 2, 2013

Researchers have engineered plants that can provide large amounts of sugar with a less intensive and expensive extractive process, the Energy Department’s Joint BioEnergy Institute announced Friday.

Institute scientists were able to develop a healthy plant whose plant cell walls or lignin are weaker and can be more easily broken down into simple sugars needed to make biofuels, without sacrificing the yield, JBEI said. Previous attempts to lower the plant’s cell wall defenses had created plants with lower biomass and a compromised ability for water and nutrient intake.

The findings were published in this month’s issue of Plant Biotechnology Journal.

Cellulosic biofuel is derived from the sugars found in the lignin of many different feedstocks including corn stover and tree pulp, as opposed to corn and other food plant fiber. Commercializing cellulosic biofuel is seen as key to developing biofuels as a real alternative to oil — but costs remain high in large part due to the sugar extracting process. Breaking down the lignin for cellulosic biofuels currently requires expensive and harsh chemicals at high temperatures. The commercial cellulosic biofuel industry produced 20,000 gallons last year.

“We now know that we can significantly re-engineer plant cell walls as long as we maintain the integrity of vessels and other key tissues,” Dominique Loque, who directs the cell wall engineering program for JBEI’s Feedstocks Division, said in a statement.

“After various pretreatments, these engineered plants exhibited improved sugar releases from enzymatic hydrolysis as compared to wild type plants. In other words, we accumulated the good stuff — polysaccharides — without spoiling it with lignin,” Loque said.

The JBEI researchers worked with the model plant Arabidopsis, but they said the “artificial positive feedback loop” strategy they used to enhance polysaccharide deposition in the fibers could be used on many other plants as components of the secondary cell wall they worked with, which “have been highly conserved by evolution.”

Increasing the plant’s cell wall content could also benefit the pulping industry and forage production, as well as increase the strength of cereal straws, reducing seed losses and “crop lodging” when plants bend near the ground, causing decreased grain quality and increased harvest costs, JBEI said.

JBEI is one of three Bioenergy Research Centers established by DOE’s Office of Science in 2007 to support research teams across disciplines and institutions to pursue scientific breakthroughs necessary to make cellulosic biofuel cost-effective on a national scale.

The centers are nearing the end of DOE’s original five-year investment cycle of $375 million in funding and await DOE’s review on their future, which is uncertain given the tight federal budgets under sequestration.