At the University of North Texas, researcher Chunliu Zhuo conducts genotyping and lignin analysis to distinguish transgenic plants from non-transgenic plants. Credit: Chunliu Zhuo/University of North Texas

Researchers identify key trigger in creation of a valuable biofuel byproduct

Scientists working with the Center for Bioenergy Innovation are developing a deeper understanding of natural processes that could make biofuel byproducts more useful. Turning biomass into marketable products will make producing cellulosic biofuel more efficient and cost-competitive.

One current biofuel byproduct is lignin, a major component in the structure of plant cells. Catechyl lignin, or C-lignin, is less common because it is synthesized only in the seed coats of some plants. But the properties of C-lignin make it a natural precursor for manufacturing carbon fiber and high-value chemicals and thus a promising choice for reuse from biorefineries.

A study coordinated by CBI analyzed what causes the creation of C-lignin. Researchers sequenced RNA from plant seed coats and performed biochemical and genetic experiments to identify a specific laccase enzyme that triggers the production of C-lignin. The study concluded that the enzyme will be a key tool for bioengineering high C-lignin content into the living tissues of commercial biomass crops such as switchgrass and poplar. The study’s results were published in The Plant Cell.

“The enzyme sticks the building blocks together to make C-lignin,” said study coauthor Chunliu Zhuo, a postdoctoral researcher at the University of North Texas. In this case, the buildings blocks are molecules of caffeyl alcohol. Because caffeyl alcohol may be toxic to a plant in certain conditions, researchers are now studying whether the timing and location of C-lignin formation is important, Zhuo said.

The long-term goal is enhancing the process to produce C-lignin at industrial scale for applications such as making carbon fiber and chemical substrates.

The Center for Bioenergy Innovation at ORNL is one of four DOE Bioenergy Research Centers focused on advancing biofuels and bioproducts for a vibrant domestic bioeconomy. CBI is accelerating the development of bioenergy-relevant plants and microbes to enable production of drop-in sustainable aviation fuel, bioproducts that sequester carbon, and sustainable replacements for plastics and other environmentally harmful products. CBI research is supported by the Biological and Environmental Research program in DOE’s Office of Science.