A novel process for phosphatidylserine production using a Pichia pastoris whole-cell biocatalyst with overexpression of phospholipase D from Streptomyces halstedii in a purely aqueous system.

This work was aimed to develop a novel phosphatidylserine (PS) production process for the food industry. The pldsh gene, encoding phospholipase D from Streptomyces halstedii (PLDsh) was cloned, and the codon optimized pldmsh gene was freely expressed by Pichia pastoris GS115 and successfully overexpressed on the cell surface of P. pastoris GS115 as displayed PLDMsh (dPLDMsh) - a whole-cell biocatalyst for PS synthesis from phosphatidylcholine and l-serine. dPLDMsh was stable over a broad range of temperatures (20-60 °C) and pH values (4.0-8.0), indicating significant improvement in stability compared with its free counterpart expressed by P. pastoris GS115. Under the optimum conditions, the conversion yield of PS was 53%, and the relative yield remained above 40% after 4 repeated batch cycles of dPLDMsh catalysis in an aqueous system. Thus, dPLDMsh and the associated reaction system provided a novel strategy for efficient PS production for the food industry.