Engineering lignin composition in plant cell walls for deconstructable biofuels feedstocks or resilient biomaterials
Tuesday, April 29, 2014: 2:45 PM
Grand Ballroom A-C, lobby level (Hilton Clearwater Beach)
Peter N. Ciesielski1, Michael Resch1, Jason Killgore2, Alexandra Curtin3, Michael E. Himmel1, Nathan S. Mosier4, Clint Chapple5 and Bryon Donohoe1, (1)Biosciences Center, National Renewable Energy Laboratory, Golden, CO, (2)Applied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, CO, (3)Applied Chemicals and Materials Division and Quantum Electronics and Photonics Division, National Institute of Standards and Tec, Boulder, CO, (4)LORRE/Ag. and Bio. Engineering, Purdue University, West Lafayette, IN, (5)Agricultural Engineering, Purdue University, West Lafayette, IN
Genetic manipulation of the biopolymers that compose plant cell walls is emerging as a powerful tool to produce designer biomass with properties that may be specifically tailored to various applications. I will present our investigation of several genetic variants of Arabidopsis: the wild type, which makes a lignin polymer of primarily guaiacyl (G) and syringyl (S) monomeric units, the fah1 mutant, which makes lignin from almost exclusively G subunits, and a ferulate 5-hydroxylase (F5H) overexpressing line (C4H:F5H) that makes lignin from S subunits. Using multiscale, multimodal imaging techniques, we show that biomass of the transgenic with predominantly S-lignin is more susceptible to deconstruction by thermochemical treatment than the other variants, and that the transgenic with predominantly G-lignin is the most recalcitrant to thermochemical deconstruction.  These structural changes in the cell wall facilitate enhanced enzymatic saccharification of the high-S transgenic tissue with respect to the wild type, while the high-G variant is clearly the least digestible of the pretreated materials. Finally, we show by contact resonance force microscopy, an atomic force microscopy technique, that cell walls of the high-S transgenic are significantly less stiff in the region of the compound middle lamella relative to wild type and high-G variant. These results imply the utility of genetic modification of lignin for enhanced biofuels production as well as specialized biomaterials applications.