Authors
Sarada Sripada - Presenter, DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison‘ and ’Wisconsin Energy Institute, University of Wisconsin-Madison
To improve the sustainability and economics of lignocellulosic biorefineries, there has been a growing interest in upgrading lignin into specialty bioproducts and biofuels through integrated chemical and biological processes. The heterogeneous depolymerized lignin mixture obtained from the chemical fractionation of biomass can be upgraded into value-added products using microbial strains capable of transforming a diverse array of phenolics into a single commodity chemical. In this study, we developed a biomass-to-bioproduct pipeline involving reductive catalytic fractionation (RCF) of poplar biomass followed by microbial funneling of the depolymerized lignin using an engineered strain of Novosphingobium aromaticivorans that produces 2-pyrone-4,6-dicarboxylic acid (PDC), a potential biomass-derived precursor for bioplastics. Considering the impact of solvent choice on reactor operating pressure and cost, RCF monomer yield, as well as microbial compatibility, we investigated RCF and PDC production with various solvents including methanol, ethanol, isopropanol, isobutanol, 1,4-dioxane, ethylene glycol, and their aqueous mixtures (5-50 vol % water). Hansen solubility parameters (HSPs) were employed to develop a non-linear regression model for RCF yields that explains the variation across the solvent mixtures. Using ethylene glycol/water (50 vol %) as the RCF solvent resulted in low reactor pressure while retaining high RCF and PDC yields, potentially improving the process economics of the biomass-to-PDC pipeline by reducing the capital cost of the RCF reactor.
