March 6, 2009

When Seth DeBolt and his research colleagues in the University of Kentucky College of Agriculture's horticulture department began researching a common weed, they hoped the results would have the potential to positively affect the efficiency of non-food crops for biofuel. After nearly a year of tedious processes with miniscule seeds, DeBolt and crew were more than encouraged as the results became clear.

"We found that we could increase the rate at which cellulose is digested to fermentable sugar and then converted into biofuel by about 150 percent," said DeBolt, assistant professor. "That's a fairly dramatic increase, and we were quite surprised."

The plant, Arabidopsis, is basically the "lab rat" of the plant world. Debolt said it's a small annual weed found throughout the temperate regions of the world. It doesn't really have any economic value on its own, however; scientists have found it valuable for genetic and molecular research because of its size, growth rate and the fact that it's a simple genome from which they can generate many mutations.

DeBolt believes recent studies convincingly show that the long-term use of corn as a biofuel crop could threaten food security. So many scientists are looking at non-food sources for biomass, including grasses that are very common and easy to grow in Kentucky such as switchgrass and eastern gammagrass and even other crops such as sweet sorghum and poplar trees. DeBolt said Arabidopsis has a lot of similarities to these plants and has yielded important information for making them more efficient for biomass.

"The genetics (of the Arabidopsis) are suitable for looking at a lot of different genetic mutations," DeBolt explained. "With that in mind, we screened for a plant with altered cellulose, knowing that we wanted to stay away from using a food-source, starchy crop such as corn. We looked for a form of cellulose that's more easily turned into biofuel. We did this using X-ray scattering and numerous mutations found in the Arabidopsis plant and ended up finding one that had very suitable properties for biofuel."

He said his team's long-term focus is not to compete with food-source biofuel crops, but to use native plants that can be grown on marginal lands to come up with more environmentally sound solutions.

DeBolt emphasized that the mutation they identified to get the desired results was nontransgenic, meaning it is not from another plant species or entirely different plant kingdom. He said one the main things researchers sought to overcome was the actual crystalline structure of cellulose itself.

"Through millions of years of evolution, plant structures developed a structure that resists being broken down by enzymes," DeBolt said. "If you can get the structure to do that, not to resist, the cellulose is easily converted to a fermentable product to make alcohol - the sugar which comprises the largest part of a plant. The plant we found that most readily converts to biofuel was not a transgenic plant. It just had a single base pair mutation in it that made its cellulose naturally less crystalline and more easily broken down."

With a provisional patent on their research, DeBolt and his team are looking forward to combining efforts with other departments within the UK College of Agriculture including plant and soil sciences, biosystems and agriculture engineering and the Kentucky Tobacco Research and Development Center. Together, they will begin carrying out research to identify, breed and find ways to provide marketable quantities of native plant species that will provide more efficient biomass for biofuel production in a state that's well suited to producing these types of crops.

"Kentucky and the surrounding states have a lot of marginal or fallowed agricultural and mined lands," DeBolt said. "I think we really have a great potential to generate biofuels as a significant portion of the state's energy requirements and hopefully do it in a way that is environmentally friendly and socially sustainable."

DeBolt's findings recently were featured in the Global Change Biology Bioenergy Journal, which exists to "promote understanding of the interface between biological sciences and the production of fuels directly from plants, algae and waste. All aspects of current and potential biofuel production, from forestry, crop production, enzymatic deconstruction and microbial fuel synthesis to implications for biodiversity, ecosystem services, economics, policy and global change are included."                   

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