Gene Cloning, Expression, and Properties of a Fibrinolytic Enzyme Secreted by Bacillus pumilus BS15 Isolated from Gul (Oyster) Jeotgal

Abstract

A Bacillus strain, BS15, showing strong fibrinolytic activity, antibacterial activity, and salt tolerance was isolated from gul (oyster) jeotgal, a Korean fermented sea food. BS15 was identified as B. pumilus. B. pumilus BS15 was able to grow in LB broth with 18% (w/v) NaCl. When culture supernatant was analyzed by SDS-PAGE, 22, 27, 35, and 60 kDa proteins were observed. The 27 kDa protein was determined to be major fibrinolytic enzyme by fibrin zymography. The gene (aprEBS15) was cloned in pHY300PLK, a Bacillus-E. coli shuttle vector. A B. subtilis transformant (TF) harboring pHYBS15 showed higher fibrinolytic activity than B. pumilus BS15, and produced the same 27 kDa protein. aprEBS15 was overexpressed in E. coli BL21 (DE3), and recombinant enzyme (AprEBS15) was purified. The optimum pH and temperature of AprEBS15 were pH 8.0 and 40 degrees C, respectively. Km and Vmax values were 0.26 mM and 21.88 mu mol/L/min, respectively. B. pumilus BS15 can be used as a starter for jeotgals and other fermented foods with high salinities.