抗水稻黄单胞菌的苏云金芽胞杆菌菌株筛选及其 活性物质

Characterization of an antibacterial substance from Bacillus thuringiensis against Xanthomonas oryzae pv. Oryzae

摘要:

【目的】从400株苏云金芽胞杆菌菌株中筛选出拮抗水稻黄单胞菌活性最好的菌株YBT-2532，并对其抑菌活性物质进行分离。【方法】对苏云金芽胞杆菌YBT-2532产生的活性物质理化特性进行测定。【结果】该活性物质对温度、蛋白酶、pH均不敏感，70 °C处理1 h仍保留有75%的活性；活性物质在pH 2.0?12.0较稳定；该活性物质溶于甲醇、微溶于乙醇、不溶于丙酮、二氯甲烷和氯仿。利用凝胶过滤、离子交换层析、固相萃取、高效液相色谱技术，对抑菌组分进行分离，并通过HPLC-IT-MS方法确定其分子量。纯化的活性组分是一种分子量为797.8 Da的强极性水溶性小分子。【结论】该活性物质性质与已知的来源于苏云金芽胞杆菌的抗菌活性物质不同，可能为新型抗菌物质。

Abstract:

[Objective] Strain YBT2532 was screened from 400 Bacillus thuringiensis strains against Xanthomonas oryzae pv. oryzae. Its antimicrobial substance was isolated. [Methods] Physical and biochemistry characteristics of the antimicrobial active substance produced by the B. thuringiensis strain YBT-2532 were determined. [Results] It is not sensitive to temperature, protease and pH. After incubation at 70 °C for 1 h, still 75% activity retained. Proteinase K, trypsin and pepsin had no effect on its activity. The active substance was stable in the pH range between 2.0 and 12.0. It can be dissolved in water and methanol, weakly dissolved in ethanol, insoluble in acetone, chloroform and dichloromethane. Purification of the active substance was achieved using gel chromatography, ion exchange chromatography, solid phase extraction and HPLC. The purified active substance was analyzed by HPLC-IT-MS. It is a polar water soluble small molecule of 797.8 Da. [Conclusion] A new antibacterial substance was obtained from an isolate of Bacillus thuringiensis.