A strain producing pullulanase was isolated from soil and mutated by UV and EMS with the increase of pullulanase activity from 1.6 to 5.4 u/mL. The fermentation conditions and medium were studied and optimized. The enzyme activity can reach 8.8 u/mL under the optimal fermentation conditions and medium. The optimal pH and temperature for enzyme are 4.6 and 75℃ respectively. It shows a high stabiliby during pH4.0～8.0 at 55℃.%从土壤中分离出一株产普鲁兰酶的菌株，初步鉴定为芽孢杆菌，通过紫外及EMS多次诱变及筛选，酶活从1.6u/mL提高到5.4u/mL。在此基础上对产酶条件进行了优化，酶活有了较大提高，最高产酶水平达8.8u/mL。初步研究了酶的性质，酶反应的最适温度和pH分别为75℃和4.6，在55 C反应条件下，酶在pH4.0～8.0范围内活性稳定。
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