Metabolic Engineering of E. coli for N-Butanol Production

Crude glycerol, a waste from the biodiesel production process, can be an abundant and renewable resource. However, the glycerol-based industry is usually affected by the cost for refinement of crude glycerol. Mukesh Saini from the Feng Chia University in Taiwan aimed to address this issue by developing a microbial process that converts crude glycerol to value-added chemicals. The team focused on engineering Escherichia coli to produce n-butanol.

The central metabolism of E. coli was rewired to improve the efficiency of glycerol metabolism. The team first studied the glycolytic flux in E. coli through the oxidation pathway of pyruvate. Next, the team then directed the flux into the oxidative pentose phosphate pathway. The team then enhanced the anaerobic catabolism for glycerol and moderately suppressed the tricarboxylic acid cycle. The resulting engineered strain enabled the production of 6.9 g/L n-butanol from 20 g/L crude glycerol.

This study shows the feasibility of manipulating key metabolic pathways. The developed technology platform may be useful for the economic viability of the glycerol-related industry.