小麦内生枯草芽孢杆菌E1R-j胞外抗菌蛋白的分离纯化和性质

通过(NH4)2SO4分级沉淀、疏水层析、PAGE切胶电洗脱、阴离子交换层析从E1R-j发酵滤液中分离纯化得到抗菌蛋白j1.经测定,j1分子量为51.9 kDa,等电点为8.7.j1不能催化昆布多糖、壳聚糖、羧甲基纤维素的水解;但能催化酪蛋白水解,其相对蛋白酶活性为384.67 U/mL.j1对蛋白酶K不敏感,具有很好的热稳定性(121℃),在pH 5～9 范围内表现稳定.对供试的5种病原真菌,j1仅对小麦全蚀病菌和苹果轮纹病菌有抑制作用.其中,对小麦全蚀菌的抑制中浓度IC50为 0.14 μg/mL.

Purification and Characterization of an Extracellular Antifungal Protein from Wheat Endophytic Bacillus subtilis Strain E1R-j

Clarifying the inhibitory mechanism of endophytic Bacillus subtilis ElR-j on Gaeumannomy-ces graminis var. tritici (Ggt) is fundamentally necessary for further efficient application of it in biological control of wheat take-all disease. Through Fractional Ammonia Sulfate Precipitation, Hydro-phobic Interaction Chromatography, PAGE-Electro Elution and Ion Exchange Chromatography we have purified an antifungal protein from the fermentation filtrate of EIR-j which was designated as jl. It has an isoelectric point of 8. 70 and an apparent molecular mass of 51. 9 KDa as measured. Jl is unable to catalyze the hydrolysis of Laminarin, chitosan, carboxymethyl cellulose. But jl can catalyze the hydrolysis of casein and the relative protease activity is measured 384. 67 U/mL. jl is resistant to protease K and is relatively stable between pH5. 0 and 9. 0 and at temperature below 121℃. According to the antifungal assay on 5 kinds of pathogenic fungi, jl inhabits only apple ring rot and wheat take-all disease pathogens. The IC_(50) of jl on Ggt was measured 0. 14 μg/mL.