Glyoxylate carboligase-based whole-cell biotransformation of formaldehyde into ethylene glycol glycolaldehyde

A novel biocatalytic system for the synthesis of industrially relevant C2 chemicals ( e.g. , ethylene glycol ( 3 )) from formaldehyde ( 1 ) was established. The biocatalytic system consisted of a newly discovered thermostable glyoxylate carboligase from Escherichia coli K-12 (EcGCL) and a lactaldehyde reductase (FucO) of E. coli K-12. EcGCL's affinity for formaldehyde was first improved by engineering the substrate access tunnel. One of the variants ( i.e. , EcGCL R484MN283QL478M ) showed a high substrate affinity and catalytic efficiency of 18 mM and 5.2 M −1 s −1 , respectively, for the condensation of two molecules of formaldehyde into one molecule of glycolaldehyde. The recombinant E. coli cells expressing both EcGCL R484MN283QL478M and FucO produced ethylene glycol ( 3 ) up to 6.6 mM from formaldehyde ( 1 ) with a bioconversion of 66% via glycolaldehyde ( 2 ), without leaving the reactants ( 1 and 2 ) in the reaction medium. This study demonstrated the biocatalytic synthesis of ethylene glycol from C1 compounds in an environment-friendly way. A novel E. coli based biocatalytic system was examined to produce ethylene glycol from formaldehyde using glyoxylate carboligase as the key enzyme.