黑曲霉F5产高温α-糖化酶酶学性质及产酒精能力研究

摘要

α-glucoamylase, the metabolite of Aspergillus niger F5, its enzymatic properties were investigated in this study. The experimental re-sults showed that, its optimum reaction temperature was 65℃, its best reaction pH was 5.0, the half-life of enzymatic thermal stability was 2.67 min at 80℃;in enzymatic kinetics, Km value was 0.836 mg/mL, and Vmax value was 2.255 mmoL/L·min. Saccharification experiments showed that saccharification rate was 67.5%for 1%starch concentration in optimum reaction conditions after 55 min. In alcohol-producing ca-pacity test, the ratio of sorghum material to water was 1∶3, 30 IU/g glucoamylase was added at 65℃and pH 5.0. After 20 h hydrolysis and cooling, 1%liquid S.cerevisiae was inoculated, and then cultivated for 9 d at 28℃. Finally, the alcohol concentration was 19.6%vol/60 g (dry substance), and liquor yield of sorghum materials reached up to 32.2%(v/w).%通过对黑曲霉F5的代谢产物糖化酶进行了酶学性质的研究，实验结果表明，该酶的最适反应温度为65℃，最适反应pH值为5.0。在80℃条件下热稳定半衰期为2.67 min；酶促动力学中，Km值为0.836 mg/mL，Vmax为2.255 mmoL/L·min。通过对1%的底物进行糖化实验，55 min后其DE值为67.5。产酒精能力测试中,料水比1∶3，添加30 IU/g原料的糖化酶，在65℃、pH5.0条件下酶解20 h，冷却接种1%液体酿酒酵母，以28℃培养9 d，酒精度为19.6%vol/60 g干物质，原料出酒率为32.2%（v/w）。