Immobilization of Phospholipase D for Production of Phosphatidylserine by a Pickering Emulsion Strategy

Abstract

As a natural phospholipid, phosphatidylserine (PS) plays a key role in the food, cosmetic, and pharmaceutical industries. Recently, substantial attention has been focused on the phospholipase D (PLD)-mediated synthesis of PS. However, the application of free PLD is usually limited by high cost, poor reusability, and low stability. In this study, PLD from Streptomyces antibiotics (saPLD) was efficiently immobilized on SiO2 through physical adsorption to develop saPLD@SiO2. The stability of the saPLD@SiO2 was higher than that of the free saPLD over an extensive range of temperature and pH conditions. Furthermore, the PS yield of saPLD@SiO2 was approximately 41% in the first cycles, and still kept 60% of its initial PS yield after 14 cycles. After a 25-day storage period, the saPLD@SiO2 retained 62.5% of its initial activity, while the free saPLD retained only 34.3%, suggesting that saPLD@SiO2 has better stability than free saPLD. A Pickering emulsion was produced by dispersing saPLD@SiO2 in solutions (ethyl propanoate and acetate/acetic acid buffer) using ultrasound. The engineered Pickering emulsion demonstrated excellent catalytic activity, with a 62% PS yield after 6 h, while free saPLD had only 18%. The results indicated that a high-performance and sustainable biocatalysis method was established for the effective synthesis of PS.