We developed a lignin-to-bioproduct processing chain to produce 2- pyrone-4,6-dicarboxylic acid (PDC) through microbial funneling of the phenolic monomers obtained by catalytic depolymerization (hydrogenolysis) of isolated lignin. Chemical and biological upgrading were used in tandem to extract greater value from the lignin fraction by converting lignin-derived aromatics to PDC. We isolated lignin under mild reaction conditions using gamma-valerolactone (GVL) and water as the solvent system and dilute sulfuric acid as a catalyst. The technoeconomic analysis of the processing chain showed the cost of lignin isolation to have a large impact on the minimum-selling-price (MSP) of PDC. More recently, we modified the “lignin-to-bioproduct” processing chain by eliminating the costly biomass fractionation step. In the new scheme, a “biomass-to-bioproduct” processing chain, we combine biomass fractionation and catalytic lignin depolymerization into a single step, while simultaneously preserving the structure of the polysaccharide fraction. Using this strategy, we were able to increase the monomer/oligomer product yield on a per kg of biomass basis vs. the two-step process. We further show that, using an engineered strain of Novosphingobium aromaticivorans DSM12444, this complex mixture of aromatic compounds can be upgraded to PDC which can be extracted from the culture broth in a simple separation and purification step (e.g., precipitation using NaCl and acid). Furthermore, the sugar stream was subjected to enzymatic and microbial digestion to produce liquid fuels. Combining these improvements over the previous process we demonstrate that an expensive part of our lignin-to-bioproduct (PDC) processing chain can be improved by using a lignin-first biomass-to-bioproduct processing chain.

Combining hydrogenolysis and microbial funneling to produce 2-pyrone-4,6-dicarboxylic acid from lignocellulosic biomass

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ACS Fall 2022

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