Secretory Expression of Pullulanase Gene from Bacillus subtilis and Its Application to Vermicelli Production

Abstract:

This study aimed to investigate the secretory expression of the pullulanase gene from Bacillus subtilis and the application of the recombinant enzyme. The BsP gene encoding pullulanase in B. subtilis strain 168 was expressed in Escherichia coli and B. subtilis, respectively. The recombinant enzymes expressed in both hosts could be secreted to the outside of cell via its own structure. The enzymatic properties of the expression products secreted to the culture medium significantly differed from those accumulated in the cytoplasm of Escherichia coli. The specific enzyme activity of recombinant enzyme BsBsP expressed in B. subtilis and secreted to the culture medium was 153.7 U/mg, which was 5.5 times higher than that of the products accumulated in the cytoplasm of E. coli. The optimum pH and temperature of BsBsP were 6.0 and 45 ℃, respectively. The recombinant enzyme BsBsP could not hydrolyze amylose, and it was considered as a type I pullulanase. Hydrolysis of starch paste with the recombinant enzyme BsBsP significantlyreduced the broken rate of vermicelli in the processing of potato starch vermicelli. B. subtilis pullulanase could use its own structure to achieve high-efficiency secretory expression, and the recombinant enzyme BsBsP is suitable for starch-based vermicelli production.