Michener, J. | bioRxiv Science

bioRxiv2017

Rapid, parallel identification of pathways for catabolism of lignin-derived aromatic compounds

This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

microbiology↗

bioRxiv2017

Construction and optimization of a heterologous pathway for protocatechuate catabolism in Escherichia coli enables rapid bioconversion of model lignin monomers

Cellulosic biofuel production yields a substantial lignin byproduct stream that currently has few applications. Biological conversion of lignin compounds into chemicals and fuels has the potential to improve the economics of cellulosic biofuels, but few microbes are able both to catabolize lignin and generate valuable products. While Escherichia coli has been engineered to produce a variety of fuels and chemicals, it is incapable of catabolizing most aromatic compounds. Therefore, we have engineered E. coli to catabolize a model lignin monomer, protocatechuate, as the sole source of carbon and energy, via heterologous expression of a nine-gene pathway from Pseudomonas putida KT2440. We next used experimental evolution to select for mutations that increased growth with PCA more than two-fold. Increasing the strength of a single ribosome binding site in the heterologous pathway was sufficient to recapitulate the increased growth. After optimization of the core pathway, we extended the pathway to enable catabolism of a second model compound, 4-hydroxybenzoate. These engineered strains will be useful platforms to discover, characterize, and optimize pathways for lignin bioconversions.\n\nHighlightsO_LIA heterologous pathway for PCA catabolism was transferred to Escherichia coli.\nC_LIO_LIEvolution identified a mutation that increased growth with PCA by 2.5-fold.\nC_LIO_LIOptimization plus further engineering allowed efficient catabolism of 4-HB\nC_LI

synthetic biology↗