Fermentation conditions and properties of a chitosanase from Acinetobacter sp. C-17

A species of bacterium with high chitosanase activity was isolated from soil samples in Haiyan City, China, and identified as an Acinetobacter species. This strain, named Acinetobacter sp. strain C-17, produced a chitosanase that was inducible and secreted into the medium. The optimal conditions for enzyme production were cells used to inoculate a medium containing 1% chitosan (pH 7.0) followed by culture at 30 degrees C. The chitosanase activity reached 1.7 U/ml when strain C-17 was incubated in a 250-ml flask under the optimal conditions for 24 h, and reached 2.8 U/ml when cells were incubated in a 3-l fermentor. The optimal pH and temperature for hydrolysis of chitosanase were 7.0 and 36 degrees C, respectively. The chitosanase activity was stable in the pH range of 5-8 and temperature range of 30-40 degrees C. The chitosanase of the strain was extracted by zinc acetate and ammonium sulfate precipitation. The molecular mass was estimated to be 35.4 kDa by SDS-PAGE.