Biosynthesis of vanillin from vanillyl alcohol by recombinant Escherichia coli cells expressing 5-hydroxymethylfurfural oxidase

The efficient valorization of lignin-derived vanillyl alcohol for the production of value-added biovanillin with enzyme or whole-cell based biotransformation is attracting increasing attention. In this study, a recombinant Escherichia coli HMFO was explored for the production of vanillin through the selective aerobic oxidation of vanillyl alcohol. The resting cells of this strain indicated a high vanillin tolerance and good biocatalytic activity over a temperature range of 10–35 °C. The vanillyl alcohol oxidation process produced vanillin as the sole product, indicating excellent reaction selectivity. Vanillyl alcohol substrate of 250 mM was converted to vanillin under optimal conditions with 96 % yield. In addition, 449.2 mM vanillin was obtained in a fed-batch experiment, providing a productivity of 1.2 g/L per hour and 90 % yield. The production of biovanillin could be further improved by using enzyme engineering and process engineering methods.