Abstract: The mutating and the screening of the original fungus were carried o ut by the ultraviolet radiation method to obtain a mutant species T1 of high pr oducting pullulan and its transformation rate of pullulan could reach 30.14%, which is 5.7 times that of the original fungus. Meanwhile, by designed ort hogonal experiments, the optimum fermentation conditions of the original fungus and the mutant fungus T1 were compared. The optimum fermentation conditions of t he mutant fungus T1 are determined as follows i.e., peptone is 0.5 g/L, saccharose 50 g/L, pH 5.0. The rate of the transformation of the carbohydrate i s mainly related to the concentration of the nitrogen source in the mutated fu ngus fermentation. At the same time, the fermentation characteristics of the ori ginal fungus and the mutated fungus were also studied. It was found that the characteristics of the mutant fungus were greatly changed.

Key words: pullulan, mutation, conditions of fermentation