普鲁兰酶产生菌的筛选鉴定及其发酵条件优化与酶学性质研究

Studies on Screening,Identification,Optimization of the Fermentation Conditions of Pullulanase-producing Strain and the Properties of Pullulanase

从淀粉厂附近土壤中筛选得到5株产普鲁兰酶的菌株,与实验室已有保藏菌株做活性对比,结果筛选得到的S1117产酶活性较高,根据其形态特征及16S rRNA序列分析,初步鉴定为芽孢杆菌。对其产酶条件进行了优化,确定了该菌株的最适发酵培养条件,其发酵54 h时酶活达到最大2.5 U/mL。初步研究了其酶学性质,其所产普鲁兰酶反应最适温度与pH分别为40℃,5.2;在60℃仍保持有80%以上酶活。

5 strains of pullulanase producing bacterial screened from soil near a starch factory were compared with the bacterium conserved in our laboratory,results a strain isolated from soil,named S1117 had a higher producing activity.It was identified as Bacillus sp.according to its morphologic,physiological and biochemical character and 16S rDNA sequence.The optimum conditions for the pullulanase production of S1117 were studied in detail and were finally determined.The time of enzyme producing is 54 h,when the enzyme activity reached 2.5 U/mL under the optimal fermentation conditions and medium.The optimal temperature and pH for enzyme are 40 ℃ and 5.2 respectively.It remained above 80 % of enzymatic activity at 60 ℃ and is stable from pH 4.6 to pH 5.2.