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

Zhong Li,Jinkai Sun,Jinxin Yan,Ping Xu,Cuiqing Ma,Chao Gao

doi:10.1038/s42004-018-0070-7

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.

Highlights

The large surplus of glycerol derived from the expanding biofuel industry raises economic and environmental concerns regarding disposal
We designed an enzymatic cascade for the conversion of glycerol into pyruvate using three enzymes: alditol oxidase from Streptomyces coelicolor A3 (ALDO), dihydroxy acid dehydratase from Sulfolobus solfataricus (DHAD), and catalase from Aspergillus niger[20]
Since tyrosine phenol-lyase has previously been used to catalyze the condensation of phenol, pyruvate, and ammonium into L-tyrosine[21], the production of L-tyrosine from glycerol, phenol, and ammonium might be achieved through the coupling of the pyruvate production cascade with tyrosine phenol-lyase

Summary

Introduction

The large surplus of glycerol derived from the expanding biofuel industry raises economic and environmental concerns regarding disposal. 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. We designed an enzymatic cascade for the conversion of glycerol into pyruvate using three enzymes: alditol oxidase from Streptomyces coelicolor A3 (ALDO), dihydroxy acid dehydratase from Sulfolobus solfataricus (DHAD), and catalase from Aspergillus niger[20]. This process eliminates the complicated phosphorylation processes typically involved, but lacks the ability to supply the reducing power required for the production of chemicals with higher degrees of reduction. Through the rational assembly of thermostable enzymes from various species, we construct a completely artificially designed in vitro biosystem for the production of valuable chemicals from glycerol

Methods

Results

Conclusion