Abstract: Strain CW₂M₃ was mutagenised from strain bacillus thermolicheniformis CW₂ by ultraviolet ray, and the activity of secreted neoamylase by CW₂M₃ is increased by 232.7% compared with that of CW₂ under the identical conditions. Moreover, strain CW₂M₃ is genetically stabile. The results of thin layer chromatography of the products from starch catalyzed by the neoamylase demonstrate that the neoamylase can be used to catalyze starch to produce isomaltooligosaccharide, including isomaltose, panose, isomaltotriose, from starch. The optimum conditions under which the neoamylase was secreted by CW₂M₃ were confirmed by orthogonal tests. The results show that the most important parameter to secrete the neoamylase is temperature for culturingCW₂M₃ and the optimum conditions to secrete the neoamylase are as follows. The strain CW₂M₃ should be cultured in the medium of 0.7% brewis, 0.7% peptone, 0.5% NaCl, pH 7.0 at 40 ℃ for 12 h, whereas the most important parameter to utilize the neoamylase is catalytic duration and the optimum conditions to utilize the neoamylase are in pH 7.0 starch system, at 65 ℃ for 1.0 h. 

Key words: neoamylase, isomaltooligosaccharide,  bacillus thermolicheniformis