Chitosanases which catalyze the hydrolytic degradation of chitosan have been used for preparation of functional chitooligosaccharides. They have also been used as biological control agent in agriculture to improve plant anti-disease abilities, hi terms of bioengineering, chitosanases have been used for generation of fungal protoplasts along with other means, providing enzyme tool in cell molecular biology. Based on the chitosanases producer of Aspergillus sp.CJ22-3 screened from soil, this dissertation incl...