Production of a surfactant- and solvent-stable alkaliphilic protease by bioconversion of shrimp shell wastes fermented by Bacillus subtilis TKU007

Abstract

An extracellular serine protease with novel surfactant- and solvent-stable alkaliphilic properties was purified from the culture supernatant of Bacillus subtilis TKU007 with shrimp shell wastes as the sole carbon/nitrogen source. The TKU007 protease showed suppressing effect on the chitosanase, which appeared at the 1st day. The molecular mass of TKU007 protease determined by sodium dodecyl sulfate-polyacryamide gel electrophoresis (SDS-PAGE) and gel filtration was approximately 28 kDa and 30 kDa, respectively. The optimum pH, optimum temperature, pH stability, thermal stability, K m, and V max of TKU007 protease was 7–11, 50 °C, pH 5–11, 50 °C, 0.13 mg/mL, and 0.86 U/mL, respectively. More than 80% of its original activity was retained even after preincubation for 10 days at 25 °C in the presence of 25% tested organic solvents. Additionally, the TKU007 protease retained 100%, 100%, 50%, and 65% of its original activity in the presence of 2% Tween 20, 2% Tween 40, 2% Triton X-100, or 0.5 mM SDS, respectively. In conclusion, the novelties of the TKU007 protease include its high stability to the solvents, surfactants, and alkali. These unique properties make it an ideal choice for application in detergent formulations and enzymatic peptide synthesis.