拮抗细菌菌株BC98-I对青椒枯萎病菌的抑制作用

拮抗细菌菌株BC98-I是从沤肥浸渍液中分离筛选到的一株对青椒枯萎病菌Fusarium oxysporum f.sp. vasinfectum具有强烈抑制作用的蜡质芽孢杆菌。菌含量为5.0×108 cfu/mL的该拮抗菌发酵液在平皿上对青椒枯萎病菌的抑制率为91.7% ±0.5%;该发酵液经高温高压灭活后对青椒枯萎病菌仍有抑制作用,抑制率为58.3% ±2.2%。经硫酸铵沉淀从发酵液中粗提到对青椒枯萎病菌具有抑制作用的拮抗蛋白粗提物,经孔碟法试验表明,浓度从5 ~60 mg/mL的粗提物对病原菌的抑菌圈直径达12 ~27 mm。显微观察显示:拮抗蛋白粗提物可造成青椒枯萎病菌菌丝异常;对孢子的抑制作用主要表现为孢子萌发产生的芽管短,部分芽管膨大形成大泡囊。该拮抗蛋白对热、蛋白酶、氯仿稳定;耐酸碱,对紫外线和离子强度部分敏感。

Inhibition of Antagonistic Bacterium BC98-I Strain againstFusarium oxysporum f.sp. vasinfectum on Sweet Pepper

Bacillus cereus BC98-I isolated from compost extracts could significantly inhibit Fusarium oxysporum f.sp. vasinfectum on sweet pepper.The relative inhibition rate of 5.0×10⁸ cfu/mL culture of BC98-I against the pathogen in petri dishes was 91.7% ±0.5%.It also showed certain inhibition when treated at high temperature and under high press.The inhibition rate of the 5.0×10⁸ cfu/mL treated culture was 58.3% ±2.2%.Its crude antagonistic protein was obtained by precipitation of the cell-free culture of BC98-I with (NH₄)₂SO₄.The test showed that the diameters of inhibition zones were 12 ~27 mm after treated by the crude substance of 5 ~60 mg/mL.The microscopical observation showed that the crude antagonistic protein could cause the growth of the hyphal abnormal. It also showed great inhibition to the germination of conidia.The germinal tube produced by conidia treated by the crude antagonistic protein was shorter than the control, part of the germinal tube expanded and formed big vacuole;while the spores in control all germinated and formed long and smooth hyphae.The antagonistic protein is thermostable, resistant to trypsin, proteinase K and chloroform, partial sensitive to ultraviolet rays and ion intensity . Its active pH range is wide, from 1.0 to 11.0.