Production, purification and functional characterization of phospholipase C from Bacillus thuringiensis with high catalytic activity

Abstract The isolated Tunisian strain of Bacillus thuringiensis was characterized by the secretion of a phospholipase C (PLC). The activity of the extracellular PLC from B. thuringiensis (PLCBt) was optimized and the enzyme was purified to homogeneity. In fact, the yield reached 50% and the apparent molecular mass was determined to be 28 kDa as analyzed by SDS-PAGE and the N-terminal sequence PLCBt was characterized by a high degree of homology with those of other Bacillus PLC. Herein, we report for the first time a thermoactive PLC with a higher specific activity of about 6000 U/mg measured at 55–60 °C and pH 7–8 using phosphatidylcholine as a substrate in presence of 0.5 mM Mg2+. PLCBt retains more than half of its maximal activity between 30–45 °C at pH 7–8.5 and tolerates pH values higher than 11. The PLCBt substrate specificity showed the following decreasing order in vitro: phosphatidylcholine >> phosphatidylethanolamine > phosphatidylserine ≥ phosphatidylglycerol; while phosphatidic acid and phosphatidylinositol were poor substrates. The PLCBt, with its biochemical properties, could be considered as a potential material for industrial and biotechnological applications. Among them, the production of emulsifiers and industrial degumming purposes either for the edible oil industry.