High-level expression and characterization of a novel phospholipase C from Thielavia terrestris suitable for oil degumming.

A novel phospholipase C gene (TtPLC) from Thielavia terrestris CAU709 was cloned and efficiently expressed in Pichia pastoris. The deduced protein sequence of TtPLC shared the highest identity of 33% with the characterized phospholipase C from Arabidopsis thaliana. The highest phospholipase C yield of 98, 970 U mL, with a protein concentration of 4.9 mg mL was obtained by high-cell density fermentation in a 5-L fermentor. The recombinant enzyme (TtPLC) was purified to homogeneity with a recovery yield of 59.1% and a specific activity of 22, 910 U mg. TtPLC was most active at pH 6.5 and 55 °C, respectively. It was stable within the pH range of 4.5-8.0 and up to 45 °C. The enzyme exhibited excellent stability in different surfactants and organic solvents, including Tween 20 (147.6%), Tween 40 (180.6%), Tween 60 (205.4%), cyclohexane (160.0%), n-octane (178.2%), n-heptane (180.7%), acetone (187.5%) etc. The application of TtPLC in crude soybean oil degumming process significantly reduced the residual phosphorus content from 135.4 mg kg to 7.9 mg kg under the optimized conditions, which satisfied the requirement of environmental friendly physical refining process for oil refining industry. Therefore, TtPLC should be a good candidate in oil refining industry.