Dicarboxylic acids are attractive biosynthetic targets due to their broad applications and their challenging manufacturing process from fossil fuel feedstock. Mesaconate is a branched, unsaturated dicarboxylic acid that can be used as a co-monomer to produce hydrogels and fire-retardant materials. In this study, we engineered nonphosphorylative metabolism to produce mesaconate from D-xylose and L-arabinose. This nonphosphorylative metabolism is orthogonal to the intrinsic pentose metabolism in Escherichia coli and has fewer enzymatic steps and a higher theoretical yield to TCA cycle intermediates than the pentose phosphate pathway. Here mesaconate production was enabled from the D-xylose pathway and the L-arabinose pathway. To enhance the transportation of D-xylose and L-arabinose, pentose transporters were examined. We identified the pentose/proton symporter, AraE, as the most effective transporter for both D-xylose and L-arabinose in mesaconate production process. Further production optimization was achieved by operon screening and metabolic engineering. These efforts led to the engineered strains that produced 12.5 g/l and 13.2 g/l mesaconate after 48 h from 20 g/l of D-xylose and L-arabinose, respectively. Finally, the engineered strain overexpressing both L-arabinose and D-xylose operons produced 14.7 g/l mesaconate from a 1:1 D-xylose and L-arabinose mixture with a yield of 85% of the theoretical maximum. (0.87 g/g). This work demonstrates an effective system that converts pentoses into a value-added chemical, mesaconate, with promising titer, rate, and yield.
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation (NSF) under research Grant BBE-1604728 and the Center for Sustainable Polymers CHE-1413862 .
- Dicarboxylic acid
- Escherichia coli
- Nonphosphorylative metabolism