Engineering Nonphosphorylative Metabolism to Generate Lignocellulose-Derived Products

Conversion of lignocellulosic biomass into value-added products provides significant environmental and economic benefits. Here we report the engineering of an unconventional metabolism for the production of TCA cycle derivatives from D-xylose, L-arabinose, and D-galacturonate. We designed a growth-based selection platform to identify several gene clusters functional in Escherichia coli that can perform this nonphosphorylative assimilation of sugars into the TCA cycle in less than 6 steps. To demonstrate the application of this new metabolic platform, we built artificial biosynthetic pathways to 1,4-butanediol (BDO) with a theoretical molar yield of 100%. By screening and engineering downstream pathway enzymes, 2-ketoacid decarboxylases and alcohol dehydrogenases, we constructed E. coli strains capable of producing BDO from D-xylose, L-arabinose, and D-galacturonate. The titers, rates, and yields are higher than those previously reported utilizing conventional pathways. This work demonstrates the potential of nonphosphorylative metabolism for biomanufacturing with improved biosynthetic efficiencies.