Development of a generalized platform to produce biochemicals from lignin

The versatility of microorganisms promises to solve some of the global challenges, such as producing fuels and chemicals from feedstocks other than petroleum. In the past two decades, considerable research has been conducted on microbial conversion of cheap, renewable biomass into value-added chemicals. However, cellulosic or sugar-based processes have been the main focus of such efforts to develop bio-refineries. Our long-term goal is to develop technologies that exploit the entire biomass, including plants (i.e., cellulose, hemicellulose, and lignin). To this end, we are developing a generalized platform that produces value-added, biomass-derived chemicals by combining upstream thermochemical depolymerization of lignin with downstream biological conversion of phenolic-like lignin-depolymerization intermediates. Specifically, by applying adaptive metabolic evolution, we have improved the ability of R. opacus to utilize various toxic phenolic compounds as sole carbon sources and to convert them into acetyl-CoA, an important biological precursor of many molecules, including triacylglycerols (TAGs). Importantly, our evolved R. opacus strains are tolerant to solvents (e.g., 1-octadecene and dioxane, potential solvents for lignin hydrogenolysis) and chemicals (e.g., ethanol and 1-butanol, biofuels). In addition, genetic engineering tools have been developed to enable engineering of pathway and regulatory genes. Our engineered R. opacus strains can be used to produce a diverse set of value-added chemicals and thus represents a prime example of how metabolic engineering can be applied to provide a generalized chemical production platform. We will present progress on the construction of a generalized platform that produces biochemicals from renewable biomass including lignin-depolymerization products.