黑曲霉AJ1958菊粉酶的产生和性质

Formation and Properties of Inulinase from Aspergillus niger AJ1958

从菊芋根际土壤中分离出一株菊粉酶（ＩｎｕｌｉｎａｓｅＥ．Ｃ．３．２．１．７）产生菌，经物理和化学诱变得高酶活黑曲霉突变株ＡＪ１９５８．该菌株在培养基（０．０７ｇ／ｍＬ菊芋提取液１０００ｍＬ，豆饼粉５ｇ，麸皮５ｇ，ＫＣＩ０．７ｇ，ＦｅＳＯ４·７Ｈ２Ｏ０．０１ｇ，ＭｇＳＯ４·７Ｈ２Ｏ０．５ｇ，ＰＨ５．０）中，于３０℃振荡培养３ｄ，酶活力可达６４μｍｏｌ·ｍｉｎ－１．酶水解反应的最适ＰＨ为３．０～４．０，最适温度为６０℃，在ＰＨ２．５～５．５的范围内和７５℃以下较稳定．适宜条件下，１０ｈ内０．０５ｇ／ｍＬ的菊粉溶液中之底物几乎１００％被酶水解．产物糖中果糖质量分数为９３％，葡萄糖质量分数为５．６％．该突变株产生的菊粉酶具有较满意的水解性和热稳定性．

A strain of inulinase(E.C.3.2.1.7)was isolated from soil of jerusalem artichoke,and was identified as Aspergillus niger.A mutant strain AJ1958 with high yield of inulinase was obtained from that strain by physical mutation and chemical mutation.The inulinase activity was up to 64 μmol . min-1 when the strain was aerobically grown at 30℃ for 72 h in a medium containing 0.07 g/mLjerusalem artichoke extract 1000 mL,beau cake 5 g,wheatbran 5 g,KCl 0.7 g FeSO4.7H2O0.01 g,MgSO4.7H,O 0.5 g and PH 5.0.The enzyme had an optimal PH of 3. 0-4. 0 and an optiaml temperature of 60 ℃.The enzyme was relatively stable between PH 2.5-5.5 and at 75℃.An inulin suspension of 0. 05 g/mL was hydrolyzed completely at PH 3.2 and 60℃ for 10 h. In total sugar of the hydrolysis product, 93% fructose and 5.6% glucose were obtained.