(640b) Development of a Generalized Platform to Produce Value-Added Chemicals from Lignocellulose

The versatility of bacteria promises to solve some of our global challenges, such as production of 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 biochemicals by combining upstream thermochemical depolymerization of lignin with downstream biological conversion of phenolic lignin-breakdown intermediates. Specifically, by applying adaptive metabolic evolution, we have improved the ability of Rhodococcus opacus to tolerate and 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). To identify the genetic causes underlying these phenotypes, we analyzed genomes and transcriptomes of evolved mutants using whole genome and whole transcriptome sequencing. In addition, genetic engineering tools have been developed to enable engineering of pathway and regulatory genes, based on our mechanistic understanding of phenolic tolerance in R. opacus. 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 combined with systems biology can be applied to provide a generalized chemical production platform.