Optimization, economization and characterization of cellulase produced by marine Streptomyces ruber

Cellulase is a very important enzyme due to its great industrial applications. Six marine strains of actinomycetes were screened for their carboxymethyl cellulase (CMCase) productivity. Streptomyces ruber was chosen to be the best producing strain. The highest enzyme production (25.6 U/ml) was detected at pH 6 and 40°C after 7 days of incubation. Plackett-Burman design was applied to optimize the different culture conditions affecting enzyme production. Results showed that a high concentration of KH2PO4, and a low concentration of MgSO4 had a significant effect on enzyme production. Rice straw was used as a low cost source of cellulose. It was found that 30 g/l rice straw was the suitable concentration for maximum enzyme production. Partial purification of cellulase enzyme using an anionexchange chromatography resulted in the detection of two different types of CMCases, type I and II, with specific activity of 4239.697 and 846.752 U/mg, respectively. Moreover, estimation of their molecular weight revealed 27.0 kDa for cellulase type I and 24.0 kDa for cellulase type II. It could be concluded that S. ruber is a powerful cellulase producer strain under our tested experimental conditions.Key words: Cellulase production, Streptomyces ruber, Plackett-Burman design, rice straw, enzyme characterization

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

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