Discovery of a novel acrylic acid formation pathway in Gluconobacter oxydans and its application in biosynthesis of acrylic acid from glycerol

Abstract

This study revealed a novel metabolic pathway of acrylic acid in Gluconobacter oxydans. First, the intermediate metabolite acrolein was confirmed by HPLC and GC-MS analyses. Then, the enzymes involved were identified based on mRNA expression analysis and gene deletion studies. This novel pathway includes three successive reactions: i) an alcohol dehydrogenase catalyzes 1,3-propanediol to 3-hydroxypropionaldehyde; ii) two isozymes, 3-hydroxyacyl-(ACP) dehydratase and 3-hydroxydecanoyl-(ACP) dehydratase convert 3-hydroxypropionaldehyde to acrolein; iii) an aldehyde dehydrogenase oxidizes acrolein to acrylic acid. An engineered Escherichia coli strain, coexpressing the glycerol dehydratase of Klebsiella pneumoniae and the 3-hydroxyacyl-(ACP) dehydratase of G. oxydans was constructed for acrylic acid production from glycerol. The recombinant strain produced 144.0 ± 9.8 mg/L of acrylic acid in a shake-flask culture. This is the first report demonstrating the biosynthetic pathway of acrylic acid via acrolein, and it provides a new approach for acrylic acid biosynthesis.