Lignin and biofuel production
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| Patrick Schnable and Ramesh Nair are conducting research to make feedstocks convert more efficiently to ethanol. |
Plant biomass is being touted as the up-and-coming source for biofuels. There's a challenge however – biomass, such as corn stover, switchgrass and other feedstocks, is tough and not easily converted to ethanol.
Ramesh Nair, associate scientist in the Plant Sciences Institute, is looking to modify feedstocks so they can be more readily converted to ethanol. He's studying lignin, a compound found in some plant cell walls, such as those found in stems. It acts like protective glue that cross-links cellulose and hemicellulose, important ingredients in making ethanol.
Nair's goal, supported by a PSI innovative grant, is to alter gene expressions to modify lignin composition in corn. Nair emphasized the word modify – lignin is needed to help a plant stand up and a reduction in lignin could be detrimental to a plant's survival.
The modified lignin will allow enzymes used in processing plant biomass to more easily access the cellulose and hemicellulose. Prior to fermentation, biomass is pretreated to separate the lignin from the other components. One of the goals of Nair's research is to reduce pretreatment costs.
"The main thing that could come from this study is that you won't have to use this expensive and very harsh, environmentally unfriendly chemical treatment to break down lignin," Nair said. The best-case scenario would be to get rid of the pretreatment stage altogether, he added.
"To make biofuels from biomass viable, we need to cut down the production costs at every point," Nair said.
Another goal of the project is to understand the biosynthesis of phenolic acids in order to modify plants to produce less of it. Not all cells have lignin, but they do all have the key ethanol ingredients, cellulose and hemicellulose. In non-lignified cells, such as those in the soft part of a leaf (not the veins), cellulose and hemicellulose are held together by phenolic acids such as ferulic and p-coumaric acid.
"Reducing phenolic acid content could help in converting the non-lignified biomass more efficiently to bioethanol," said Nair.
These modifications could also result in silage that is better digested. Silage is the fermented plant material fed to cows and sheep.
Nair brings his expertise in lignin and phenolic acid to this project, which is taking place in Patrick Schnable's lab. In collaboration with Schnable, associate director of the Plant Sciences Institute, he'll determine which genes to alter by using molecular markers and genomics approaches. Once corn plants with modified feedstock composition are developed, Paul Scott, a USDA research geneticist in the agronomy department and a member of Center for Plant Genomics, will test them for efficiency in ethanol production. Nair, Schnable and Scott, are co-principal investigators on this project.
