Estimation of Protease Enzyme Bioactivity Isolated from Bacterial Strains

Fifteen bacterial strains were isolated from soil samples collected from Northern East region of the delta Egypt. Bacterial strains were screened for proteolytic activity on saline skim milk agar medium where the most potent protease producer strain was identified by maximum diameter of the clear zone formed; 22 mm ± 1.0, highest concentration (1000 µg/mL) and highest activity; 350 U/mL The selected bacterial strain was characterized by Gram stain, morphologically and by biochemical tests where it was identified as Bacillus species. Protease enzyme was extracted using Gelatin yeast extract glucose broth then partially purified by saturation with ammonium sulphate followed by dialysis. A final purification step was done using High performance liquid chromatography. Molecular weight and purity of the extracted protease were determined using SDS gel electrophoresis and was estimated to be 30 kDa. The effect of different factors, viz pH, temperature and surfactants, on the activity and stability of the extracted protease was studied. The extracted protease showed highest relative activity at pH 10 and 35 ºC. While it showed stability at pH range 8 - 11 and temperature range 30 ºC - 50 ºC. The effect of Tween-80 (1%) and SDS (1%) showed 1% protease activity inhibition while concentration (2%) of both surfactants showed 10% and 12 % activity inhibition, respectively. In the current study, the extracted protease enzyme exhibited potential properties and it showed activity in the presence of surfactants, therefore, is recommended for further research work and enzyme-based industrial applications to be used in different industries.