Alkaline protease production by alkaliphilic marine bacteria isolated from Marsa-Matrouh (Egypt) with special emphasis on Bacillus cereus purified protease

Abstract

Among the eighteen (18) alkaliphilic marine bacterial isolates studied in ten sampling sites in Marsa-Matrouh beaches, the highest alkaliphilic and proteolytic activities were detected in Bacillus cereus. Alkaline protease from B. cereus was purified by ammonium sulfate precipitation and Sephadex G-200. The molecular mass determined using SDS-PAGE, was nearly 31.0 39 kDa. Some fundamental properties like effects of different temperatures, pH, metal ions (Ca²⁺, Mg²⁺, Cu²⁺, Pb³⁺, Mn²⁺ and Cd²⁺) and ethylene diamine tetraacetic acid (EDTA) on protease activity were also studied. Maximum activities were obtained at pH 10, 50°C and only Cu²⁺ ions enhanced the relative enzyme activity up to 112%. The application of alkaline protease for the removal of blood stains from cotton cloth indicates its potential use in detergent formulations. B. cereus protease showed excellent stability in the presence of locally available detergents and retained about 60% of its activity with most of them even after 3 h of incubation at temperature of 50°C.

Key words: Protease producing bacteria, detergents, Bacillus cereus, purification, enzyme stability and activity.