Systematically engineering Escherichia coli for enhanced production of 1,2-propanediol and 1-propanol.

Abstract

The biological production of high value commodity 1,2-propanediol has been established by engineering the glycolysis pathway. However, the simultaneous achievement of high titer and high yield has not been reported yet, as all efforts in increasing the titer have resulted in low yields. In this work, we overcome this limitation by employing an optimal minimal set of enzymes, channeling the carbon flux into the 1,2-propanediol pathway, increasing NADH availability, and improving the anaerobic growth of the engineered Escherichia coli strain by developing a cell adaptation method. These efforts lead to 1,2-propanediol production at a titer of 5.13 g/L with a yield of 0.48 g/g glucose in 20 mL shake flask studies. On this basis, we pursue the enhancement of 1-propanol production from the 1,2-propanediol platform. By constructing a fusion diol dehydratase and developing a dual strain process, we achieve a 1-propanol titer of 2.91 g/L in 20 mL shake flask studies. To summarize, we report the production of 1,2-propanediol at enhanced titer and enhanced yield simultaneously in E. coli for the first time. Furthermore, we establish an efficient system for the production of biofuel 1-propanol biologically.