Preparation of 3-hydroxy propionic acid from levulinic acid by using Baeyer–Villiger monooxygenase as a key enzyme

Levulinic acid is one of the representative biomass-derived feedstocks. Thereby, the production of 3-hydroxypropionic acid (3-HP) from levulinic acid was investigated by using Baeyer–Villiger monooxygenase (BVMO) as a key enzyme. Butyl levulinate was converted into 3-acetoxy propionic acid butyl ester (3-APBE) by the BVMOs, which can be transformed into 3-HP, acetic acid, and butanol by hydrolysis of the ester bonds. The biotransformation performance was improved by engineering the BVMOs and their gene expression systems as well as host cells. Ultimately, 3-APBE was produced to 0.52 mM from 1 mM butyl levulinate by the BVMO variant from Pseudomonas putida KT2440 (i.e., PpBVMO_C302L), which was expressed in Escherichia coli BL21(DE3). Moreover, structural analyses suggested the potential mutation sites for enhancing substrate binding and catalytic efficiency. This study provided a scalable biocatalytic route for the conversion of biomass-derived feedstocks into valuable chemical products.