盾壳霉是油菜菌核病菌(核盘菌)的一种重寄生菌,为了探索几丁质酶在盾壳霉寄生核盘菌过程中的作用,本文研究了影响盾壳霉几丁质酶活性的因子. 结果表明,盾壳霉几丁质酶酶促反应的最适温度为50 ℃,最适pH 8.0. 当温度不高于50 ℃、pH在5.0-9.0范围内酶活性较稳定. 一些金属离子,包括Mg^2+、Fe^2+、Ca^2+、Ba^2+和Mn^2+等,对盾壳霉几丁质酶活性有促进作用,而另外一些金属离子,包括Zn^2+ 和Cu^2+,却对盾壳霉几丁质酶活性发挥有抑制作用. 一定浓度的草酸(1-4 mmol L^-1)和硼酸(25-75 mmol L^-1)可显著提高盾壳霉几丁质酶活性. 本文还就上述结果的生物学意义和潜在利用价值进行了讨论. 图6 表1 参19
Coniothyrium minitans is an important mycoparasite of Sclerotinia sclerotiorum (Lib.) de Bary, the causal agent of Sclerotinia stem rot of oilseed rape. In order to elucidate the role of chitinase produced by C. minitans in mycoparasitism on S. sclerotiorum, the factors affecting the chitinase activity of the C. minitans chitinase were characterized in this study. Results showed that the activity of the C. minitans chitinase was highest at 50 ℃ and pH 8.0. The enzyme was stable when the ambient pH ranged from 5.0 to 9.0, whereas lost its activity when it was treated at 60 ℃ for 10 min. The activity of the chitinase was significantly improved by some ions including Mg^2+, Fe^2+, Ca^2+, Ba^2+ and Mn^2+,while it was significantly suppressed by Zn^2+ and Cu^2+. The activity of the C. minitans chitinase was enhanced by boric acid at 50-100 mmol L^-1 and oxalic acid at 2-8 mmol L^-1. The importance of these factors in mycoparasitism of C. minitans on S. sclerotiorum and their potential applications in biological control of the pathogen were discussed in this paper. Fig 6, Tab 1, Ref 19