Highly Efficient Production of Diacylglycerols via Enzymatic Glycerolysis Catalyzed by Immobilized MAS1-H108W Lipase

Abstract

Developing highly efficient and cost-effective immobilized biocatalysts is essential for optimizing diacylglycerol (DAG) production via biotransformation of natural oil. To address this, the 1,3-regiospecific MAS1-H108W lipase, derived from marine Streptomyces sp. strain W007, was produced through high-density fermentation (20 °C, pH 7.0, 132 h). This lipase was immobilized by XAD1180 resin adsorption, yielding an immobilized MAS1-H108W lipase with a lipase activity of 4943.5 U/g and a protein loading of 201.5 mg/g under selected conditions (lipase/support ratio 100 mg/g, initial buffer pH of 8.0). After immobilization, the lipase maintained its optimal temperature at 70 °C and shifted its optimal pH from 7.0 to 8.0, along with enhanced thermostability. The immobilized MAS1-H108W lipase demonstrated superior efficiency in DAG synthesis compared to non-regiospecific immobilized MAS1 lipase and commercial lipases (Novozym 435 and Lipozyme RM IM). Under the optimized reaction conditions (reaction temperature 60 °C, olive oil/glycerol molar ratio 1:2, adding amount of immobilized MAS1-H108W lipase 1.0 wt.%), a maximum DAG content of 49.3% was achieved within 4 h. The immobilized lipase also exhibited excellent operational stability, retaining 81.9% of its initial production capacity after 10 reuse cycles. Furthermore, in the glycerolysis of various vegetable oils (corn oil, rapeseed oil, peanut oil, sunflower oil, and soybean oil), the DAG content catalyzed by immobilized MAS1-H108W lipase consistently exceeded 48%. This work provides a highly efficient and economical immobilized biocatalyst for DAG production, and highlights the significant potential of regioselective lipases in promoting efficient DAG synthesis via glycerolysis.