DENTON (UNT), Texas -- New discoveries in plant biology may allow UNT researchers for the first time to create new bioproducts from lignin, including carbon fiber and improved animal feedstock. The discoveries also will help scientists around the world better understand lignin, a substance that makes plants woody and firm.
University of North Texas Distinguished Research Professor Richard Dixon, who also works as a member of the U.S. Department of Energy's BioEnergy Science Center (BESC), said the new discoveries, made in collaboration with scientists at the U.S. Department of Energy's Great Lakes Bioenergy Research Center (GLBRC), show that scientists can modify lignin in ways previously thought impossible. The first of the two discoveries involves the creation of lignin in which more than 95 percent of the building blocks have an altered chemical structure.
"We thought plants developed their normal lignin structures for important reasons, and modifying their lignin too much would hurt the plant, maybe leave them unable to stand or grow," he said.
Examining a genetically modified plant, researchers discovered for the first time that modifying the gene responsible for the last step of lignin production didn't hurt the plant's growth in the lab environment. The plant actually developed a new type of lignin.
A second discovery involves C-lignin, a linear polymer found in high concentrations in seed coats of plants including vanilla orchids and species of cactus. Because of their rarity, neither plant is likely to become a source of industrial processing for bioproducts, Dixon said.
However, Dr. Fang Chen, a research professor in Dixon's group, has been able to identify for the first time several other plants, including some that are already used commercially, that produce C-lignin as well as traditional lignin in their seed coats.
"This discovery means we have found plants that produce separate types of lignin natrually," Dixon said. "This creates new opportunities for us to make materials for bioproducts, such as carbon fiber."
Dixon and Chen are working with UNT College of Engineering Professors Nandika D'Souza and Sheldon Shi to determine what types of bioproducts can be created from the new lignins, which have very different chemical structures from common lignin.
"Because of Dr. Dixon's discoveries, the major stumbling block for making bioproducts from lignin is removed. A linear molecule solves the problem presented by the more common network lignin which cannot be used in current processing equipment easily. Fibers, coatings and solid materials that are flame retardant for aerospace and buildings are now possible," D'Souza said. "Products like converted carbon will result in naturally sourced products we currently use non-natural sources for."
The latest new lignin structure research was published in PNAS, Proceedings of the National Academy of Sciences of the United States of America.
The C-Lignin research was published in Plant Cell, produced by the American Society of Plant Biologists.
Dixon worked on the projects with researchers from the University of Wisconsin-Madison, the Samuel Roberts Noble Foundation, the U.S. Department of Energy's BioEnergy Science Center in Oak Ridge, Tennessee, and the U.S. Department of Energy's Great Lakes Bioenergy Research Center in Madison, Wisconsin.