Chien-Yuan Lin1,2,3, Bryon S Donohoe1, Yannick J Bomble1, Haibing Yang4,5, Manal Yunes1,6, Nicholas S Sarai1,7, Todd Shollenberger1, Stephen R Decker1, Xiaowen Chen8, Maureen C McCann4, Melvin P Tucker9, Hui Wei10, Michael E Himmel11. 1. Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA. 2. Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, 94608, USA. 3. Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. 4. Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA. 5. South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. 6. Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, 80309, USA. 7. Division of Chemistry and Chemical Engineering 210-41, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA, 91125, USA. 8. National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA. 9. National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA. Melvin.Tucker@nrel.gov. 10. Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA. Hui.Wei@nrel.gov. 11. Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA. Mike.Himmel@nrel.gov.
Abstract
BACKGROUND: Pretreatments are commonly used to facilitate the deconstruction of lignocellulosic biomass to its component sugars and aromatics. Previously, we showed that iron ions can be used as co-catalysts to reduce the severity of dilute acid pretreatment of biomass. Transgenic iron-accumulating Arabidopsis and rice plants exhibited higher iron content in grains, increased biomass yield, and importantly, enhanced sugar release from the biomass. RESULTS: In this study, we used intracellular ferritin (FerIN) alone and in combination with an improved version of cell wall-bound carbohydrate-binding module fused iron-binding peptide (IBPex) specifically targeting switchgrass, a bioenergy crop species. The FerIN switchgrass improved by 15% in height and 65% in yield, whereas the FerIN/IBPex transgenics showed enhancement up to 30% in height and 115% in yield. The FerIN and FerIN/IBPex switchgrass had 27% and 51% higher in planta iron accumulation than the empty vector (EV) control, respectively, under normal growth conditions. Improved pretreatability was observed in FerIN switchgrass (~ 14% more glucose release than the EV), and the FerIN/IBPex plants showed further enhancement in glucose release up to 24%. CONCLUSIONS: We conclude that this iron-accumulating strategy can be transferred from model plants and applied to bioenergy crops, such as switchgrass. The intra- and extra-cellular iron incorporation approach improves biomass pretreatability and digestibility, providing upgraded feedstocks for the production of biofuels and bioproducts.
BACKGROUND: Pretreatments are commonly used to facilitate the deconstruction of lignocellulosic biomass to its component sugars and aromatics. Previously, we showed that iron ions can be used as co-catalysts to reduce the severity of dilute acid pretreatment of biomass. Transgenic iron-accumulating Arabidopsis and rice plants exhibited higher iron content in grains, increased biomass yield, and importantly, enhanced sugar release from the biomass. RESULTS: In this study, we used intracellular ferritin (FerIN) alone and in combination with an improved version of cell wall-bound carbohydrate-binding module fused iron-binding peptide (IBPex) specifically targeting switchgrass, a bioenergy crop species. The FerINswitchgrass improved by 15% in height and 65% in yield, whereas the FerIN/IBPex transgenics showed enhancement up to 30% in height and 115% in yield. The FerIN and FerIN/IBPexswitchgrass had 27% and 51% higher in planta iron accumulation than the empty vector (EV) control, respectively, under normal growth conditions. Improved pretreatability was observed in FerINswitchgrass (~ 14% more glucose release than the EV), and the FerIN/IBPex plants showed further enhancement in glucose release up to 24%. CONCLUSIONS: We conclude that thisiron-accumulating strategy can be transferred from model plants and applied to bioenergy crops, such as switchgrass. The intra- and extra-cellular iron incorporation approach improves biomass pretreatability and digestibility, providing upgraded feedstocks for the production of biofuels and bioproducts.
Entities:
Keywords:
Ferritin; High-throughput hot-water pretreatment; Iron co-catalyst; Perls’ Prussian blue staining; Saccharification; Sugar release; Transgenic switchgrass
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