产普鲁兰酶蜡样芽孢杆菌的分离鉴定及酶学性质研究

Isolation of Bacillus cereus producing pullulanase and its enzymatic characterization

利用选择性培养基从广西南宁淀粉加工厂附近土壤中分离出一株具有产普鲁兰酶能力的野生菌株GXBC-2。该菌株革兰染色为阳性,形成芽孢,菌体细胞杆状,结合生理生化特征和16S rDNA序列分析,初步鉴定该菌株为Bacillus cereus GXBC-2。对该菌所产普鲁兰酶的性质研究表明:酶的最适反应温度为50℃,在30～50℃范围内稳定,最适pH为7.0,稳定pH范围为6～8.5。产物经HPLC分析证明,该酶能水解普鲁兰糖产生麦芽三糖,对可溶性淀粉不起作用,所以该酶属于I型普鲁兰酶。

An pullulanase producing strain, namedas GXBC-2, was isolated from the soil close to a starch processing plants in Nanning, Guangxi. The cells of the strain GXBC-2 were gram-positive, sporulation and rod-shaped. The morphological, physiological characterization and 16S rDNA sequences analysis indicated that the strain GXBC-2 was closely relative to Bacillus cereus. The characteristics of the pullulanase were also discussed. The optimum temperature and pH for the enzyme were determined as 50 ℃ and 7.0 respectively. The stable temperature and pH range were 30-50 ℃ and 6-8.5 respectively. The results of HPLC of products from pullulan by the pullutanase demonstrated that the enzyme can be used to produce maltotriose from pullulan, but it could not catalyze starch, So this enzyme belong to type I pullulan enzymes.