One-pot bio-synthesis of propyl gallate by a novel whole-cell biocatalyst

• Whole-cell biocatalyst was used to catalyze the transesterification.
• Study on reaction mode was performed for improving PG yield.
• This study presented an ecofriendly and efficient way for propyl gallate production.

Propyl gallate has an excellent antioxidative capacity and some pharmaceutical potentials. In order to examine the feasibility for one-pot bio-synthesis of propyl gallate catalyzed by a whole-cell biocatalyst in organic media, a whole-cell biocatalyst of Aspergillus niger was prepared and utilized to catalyze the transesterification with tannic acid as a raw material. Furthermore, both the catalytic system and the reaction mode were optimized to further improve the conversion rate of substrate. The result shows that a promising conversion rate, 43%, was achieved by the pH-tuned mycelium-bound tannase. The rate is over than or very close to that achieved by isolated tannase. The study on reaction mode indicates that the simulated continuous catalysis is the most suitable to the transesterification as compared to batch catalysis and batch catalysis coupled with product separation. Accordingly, the one-pot bio-synthesis of propyl gallate by the novel whole-cell biocatalyst has such three advantages as easy operability of the biocatalyst, high efficiency of reaction mode, and the abundance of the natural raw material, which will contribute to constructing an efficient and eco-friendly method for one-pot synthesis of propyl gallate in an economical and ecological manner.