以高产β-葡萄糖苷酶米曲霉为出发菌株,经紫外-60Co复合诱变处理,用不同葡萄糖浓度梯度的β-葡萄糖苷酶鉴定平板筛选,在含4%葡萄糖的鉴定平板上获得1株抗葡萄糖阻遏的突变株ASPE0485,β-葡萄糖苷酶水解酶活提高1.78倍,达到17.65U/mL。ASPE0485所产β-葡萄糖苷酶与高浓度葡萄糖反应,薄板层析和高效液相色谱检测反应产物有龙胆低聚糖,表明ASPE0485所产β-葡萄糖苷酶具有转苷活性;对酶转化葡萄糖生产龙胆低聚糖的反应条件进行了优化:当底物葡萄糖浓度为60%,pH3.0,反应温度为50℃,转化周期为72h,龙胆低聚糖累计达到最大,为44.16g/L。

A mutant from Aspergillus oryzae which can synthesize β-glucosidase when high concentration glucose exists,was obtained by using agar plate screening techniques,after mutation by UV-60Co.The mutant strain was isolated from the agar plate,which contains 4% glucose.In liquid state fermentation,the mutant strain produced high β-glucosidase activities,which were 17.65IU after 4 days’ culturing.And these were 2.78 times that of the starting strain.The activity of the expressed enzyme was measured by the assay of transglucosidation reaction and the transglucosidation product was identified by TLC and HPLC.At 60% glucose,50℃,pH3.0,and 72 h reaction time,the gentiooligosacharide reached 44.16 g/L.