菊粉酶产生菌的选育及发酵条件

Screening of Inulinase-Producing Strain and Fermentation Conditions

野生型黑曲霉ＡＪ１４０５经紫外线、硫酸二乙酯和亚硝基胍等多代诱变处理，获得一株产菊粉酶（ＩｎｕｌｉｎａｓｅＥ．Ｃ．３．２．１．７）能力较高的变异菌株ＡＪ１９５８．连续传代１０次，ＡＪ１９５８突变株无衰退，是稳定的变异菌株．其产生的菊粉酶只被菊粉（Ｉｎｕｌｉｎ），而不被蔗糖、淀粉、纤维素、葡萄糖或果糖诱导．在１０００ｍＬ０．０７ｇ／ｍＬ菊芋提取液中添加豆饼粉５ｇ，麸皮５ｇ，２５０ｍＬ三角瓶中装５０ｍＬ培养液，于３０℃，１２０ｒ／ｍｉｎ旋转式摇床振荡培养３ｄ，酶活力可达６４μｍｏｌ·ｍｉｎ（－１）．Ｋ＋，Ｆｅ（２＋），Ｍｇ（２＋）对酶形成有促进作用．

Mutant strain AJ1958 capable of highly yielding inulinase was obtained from the original strain Aspergillus niger AJ1405 by means of physical mutation caused by ultraviolet rays and chemical mutation caused by DES and NTG. The inulinase activity of strain AJ1958 reached 55. 6μmol·min-1, which was 4. 2 times that of the original strain AJ1405. Mutant strain AJ1958 was still stable in producing inulinase through incubating continuously ten generations. The inulinase activity of strain AJ1958 was induced by inulin, but not by sucrose, raffinose, cellulose, glucose or fructose.The inulinase activity was up to 64 pmol. min-1 when the strain was aerobically grown at 30 aC for 72h in a medium containing 1 000 mL of 0. 07 g/mL jerusalem artichoke extract, 5 g of beancake, 5 g of wheatbran. The enzyme producing was promoted by K+, Fe2+ and Mg'+.