Structural Studies of Deuterium-Labeled Switchgrass Biomass

Small-angle neutron scattering (SANS) is being used to study the molecular structure of tiller biomass from switchgrass, a perennial North American prairie grass that is being developed as a bioenergy crop. To enable the expanded application of SANS methods, switchgrass plants were cultivated in hydroponic media containing 50% D₂O to produce tiller biomass with 34% deuterium incorporation. Characterization of the deuterated biomass found chemical and physical properties similar to the same cultivar grown hydroponically in H₂O but with slightly increased lignin content. Surprisingly, the deuterated switchgrass was found to be less recalcitrant to enzymatic hydrolysis. Investigation with transmission electron microscopy found changes in lignin deposition patterns in deuterated cell walls. The partially deuterated switchgrass and its control were studied by contrast variation SANS to evaluate deuterium incorporation into the different plant polymers.