(284e) Synergistic Impact of Natural Variant Or Transgenic Feedstocks Combined With Consolidated Bioprocessing

Synergistic Impact of Natural Variant or Transgenic Feedstocks Combined with Consolidated Bioprocessing

Authors:

Kelsey L. Yee^1,3, Miguel Rodriguez Jr.^1,3, Olivia A Thompson^1,3, Wellington Muchero^1,3, Jay Chen^1,3, Lee E. Gunter^1,3, Sara S. Jawdy^1,3, Charleson Poovaiah^3,5, Hui Shen^3,4, Nancy L. Engle^1,3, Angela Ziebell^2,3, Robert W. Sykes^2,3, Erica Gjersing^2,3, Scott D. Hamilton-Brehm^1,3, Chunxiang Fu^3,4, Zeng-Yu Wang^3,4, James G. Elkins^1,3, Mark F. Davis^2,3, Timothy J. Tschaplinski^1,3, Gerald A. Tuskan^1,3, and Jonathan R. Mielenz^1,3

¹Bioscience Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6226, USA

²National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, 80401-3305, USA

³BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6226, USA

⁴The Samuel Roberts Noble Foundation, Ardmore, OK, 73401, USA 

⁵University of Tennessee, Department of Plant Sciences, Knoxville, TN, 37996, USA

Abstract:

Populus and switchgrass are dedicated bioenergy feedstocks and their inherent recalcitrance to bioconversion is one of the major economic hurdles for the production of biofuels. Implications of improvements in these feedstocks through use of natural variant and transgenic selection will be discussed with the goal of moving towards an improved phenotype which maintains normal growth characteristics and has improved bioconversion yields. Microbial bioconversion assays of the feedstocks were performed with a traditional enzymatic hydrolysis and yeast fermentation as well as a consolidated bioprocessing platform using bacterial species producing their own biomass-degrading enzymes. We examined Populus variants from two common garden field sites, which have a mutation that leads to reduced lignin content up to -16%. We also examined transgenic switchgrass lines with genetic modifications in the lignin pathway. The results showed superior conversion yields for the transgenic and the natural variants compared to their controls. We concluded that transgenic switchgrass and natural variant Populus sources have reduced recalcitrance and are a valuable resource for producing economical biofuels. We also determined that when characterizing new biomass sources, in vitro assays such as sugar release should be supplemented with in vivo fermentation tests which we have shown to detect inhibitory compounds.