枯草芽孢杆菌B-916胞外抗菌蛋白质的性质

Properties of Antifungal Proteins Secreted by Bacillus subtilis Strain B-916

用硫酸铵分级沉淀枯草芽孢杆菌B-916胞外抗菌蛋白质,共获得8个蛋白质粗提物,其中硫酸铵饱和度为40%～50%和50%～60%提取的粗蛋白质具有较强的抑菌活性,研究结果表明:硫酸铵饱和度40%～50%和50%～60%提取的粗蛋白质浓度分别为17.261 μg/ml和18.899 μg/ml,上述两者对水稻纹枯病菌和水稻恶苗病菌有较强的抑菌活性,对马铃薯晚疫病菌则没有抑菌活性;当温度高于40 ℃时抑菌活性均降低,但在120 ℃时仍有部分抑菌活性;对pH值适应范围较宽,但在pH值为13.6时抑菌活性均丧失;经蛋白酶K、蛋白酶E、胃蛋白酶、胰蛋白酶和木瓜蛋白酶处理后,抑菌活性均下降.SDS-PAGE电泳结果表明枯草芽孢杆菌B-916能分泌多种蛋白质,其中硫酸铵饱和度40%～50%和50%～60%提取的粗蛋白质中相对分子质量为 48 000的蛋白质可能为抗菌蛋白质.硫酸铵饱和度40%～50%和50%～60%提取的粗蛋白质经Sephadex G-100层析后检测到4个蛋白质吸收峰.

The filtrated Bacillus subtilis strain B-916 was precipitated in grades with the ammonium sulfate to draw the antifungal proteins, and eight crude proteins were obtained. Two crude proteins drawn with ammonium sulfate at 40%-50% and 50%-60% saturation showed strong antifungal activities. The concentrations of these crude proteins were 17. 261 μg/ml and 18. 899 μg/ml, respectively. Both of the proteins showed high antifungal activities against R. solani, F. moniliforme while no antifungal activity against P. infestans. Antifungal activities of the two proteins against R. solani decreased when the temperature was more than 40 ℃. When the temperature climbed to 120 ℃, some of the antifungal activities were kept. The antifungal activities of the two proteins were kept stable and high in a broad range of pH value, but lost when pH value went up to 13.6 and partly kept after treated with protease K, protease E, Pepsin, Papatin and Trypsin. Results of SDS-PAGE showed that Bacillus subtilis B-916 could secret many kinds of proteins. Among them, the protein with molecular weight of 48 000 drawn with ammonium sulfate at 40%-50% and 50%--60% saturation may be an antifungal protein. Crude proteins drawn with ammonium sulfate at 40% -50% and 50% -60% saturation were purified on the chromatographic column of Sephadex G-100 and four peaks were detected.