Production of value-added chemicals from glycerol using in vitro enzymatic cascades

Abstract

The large surplus of glycerol derived from the expanding biofuel industry raises economic and environmental concerns regarding disposal. In vitro synthetic biology is emerging as a useful biomanufacturing platform while the conversion of glycerol is rarely investigated. Here we develop a thermostable in vitro synthetic biosystem consisting of three enzymatic cascades for the biotransformation of glycerol into valuable chemicals with different degrees of reduction. Condensation of glycerol, phenol, and ammonium into l-tyrosine is achieved using four enzymes without the assistance of NAD+/NADH-related redox reactions. Production of chemicals with high degrees of reduction (e.g., optically pure l-lactate and d-lactate) is also verified through coupling with an NADH-regeneration system. The biotransformation of glycerol and ammonium into l-serine is achieved using four enzymes with self-sufficient NADH recycling.