Characterization of an Oxidant and Detergent Stable Alkaline Protease Produced from a Novel Isolate Bacillus sp. Strain

Abstract

Isolation, partial purification and characterization of a protease from an alkaliphile Bacillus sp. strain PX6 isolated from soil sample. For this purpose, the growing and the enzyme producing abilities were researched either in different temperatures or in different pH ranges, and the optimal enzyme production was obtained at pH 8.0 and 40°C. The optimum pH and temperature of the enzyme was determined at pH 8.0 and 50°C. After a pre-incubation of 60 min at 30-50°C, original activity of the enzyme was conserved 69%, and at 60-110°C original activity of the enzyme was conserved 13%. After pre-incubation of 24 h, the original activity was increased 55% at pH 6.0-9.0, retained 88% at pH 10.0 and decreased 13% at pH 11.0-12.0. While the PX6 protease was pre-treated with 2.5 mM MgCl2, BaCl2, ZnCl2, CaCl2, MnCl2, NaCl, KCl atambient temperature for 60 min, the original activity was retained 34%, 23%, 60%, 31%, 43%, 63%, 71%, respectively, it was induced 17% with FeCl2. With a pre-treatment of 60 min, enzyme activity was retained 40%, 29%, 57% in the presence of 2.5 mM EDTA, 4 M Urea, 0.5% SDS respectively, while it increased 260%, 329%, 186%, 280%, 134% in the presence of (0.5%) Triton X-100, Tween 80, Tween 20, H2O2, βMercaptoethanol, respectively. As a serine protease inhibitor, PMSF (0.5%) almost totally inhibited the activity. After pre-incubation of 60 min with commercial detergents at 30°C, activity of the enzyme PX6 was conserved 100% with 3.5 mg/ml solid laundry detergent, 31% with 0.5% (v/v) 4.6% sodium hypochlorite and 23% with 0.5% (v/v) dishwashing liquid. According to the results, the PX6 protease is alkaline and thermo-tolerant. To be stable and inductive against various detergents, surfactant and oxidizing agents, shows that this enzyme can be used in detergent, paper and textile industries and also in detergent formulations by having the effectiveness to enhance the effect of commercial detergents

Keywords

• Bacillus sp., Alkaline protease, Detergent, Thermo-tolerant, Oxidant