Production and Partial Characterization of Chitosanases from a Newly Isolated Bacillus cereus

Abstract

The production of chitosanases by a newly isolated Bacillus cereus TP12.24 was studied both in shake flask and fermenter cultures. The M9-chitosan medium was found most suitable with 0.5% chitosan as a sole carbon source optimized under aerobic growth conditions at pH 6.0 and 30°C. The
specific rates of growth, substrate consumption, and enzyme production were improved using controlled completely aerobic conditions in 2-l fermenter. While the yield of biomass was considerably increased, the enzyme yield was on the contrary decreased. As a result, the volumetric chitosanases productivity was 43.55 U/l h, which was 1.2 times that obtained from shake flask culture due to higher specific rates of chitosan consumption and chitosanases production. In this work, the crude chitosanases from Bacillus cereus TP12.24 showed their optimal pH and temperature at 6.5 and 55°C, while the stabilities to pH and temperature were found at 3.0-8.0 and 30-50°C, respectively. The Bacillus cereus chitosanases could be used for preparing the chitosano-oligosaccharides under mild temperature.