Kinetic Behavior of Free and in situ Immobilized Chitosanases Produced by the Fungus Mucor rouxii

In the present study, characteristics of free and in situ immobilized (pellets of Mucor rouxii) chitosanases were investigated. Tests included chitosanase from the culture filtrate (free form) and in situ chitosanase as an immobilized form. Growth parameters of M. rouxii revealed that maximum yield of biomass and enzyme activity (2.6 g /100 and 2.4 U/ml) occurred when molasses was used in the growth medium at a 3% concentration. Effect of pH greatly affected the fungus growth; maximum production of biomass and enzyme activity was obtained at pH 5.5, however, at pH 3.0 a formation of an exopolysaccharide bioflocculant was occurred as a form of self-protection by the fungus under the abiotic stress condition. Optimum pH for free and in situ immobilized enzymes was 6.0, whereas optimum temperature range for activity of free and in situ immobilized enzymes were 30-50°C and 40-65°C, respectively. Free and in situ immobilized enzymes display broad specificity towards colloidal chitin, chitosans with different degree of acetylation and Avicel. Values of K and V , for the extracted chitosanase are nearly the same for hydrolyzing of chitosans with different degree m max of acetylation.