海洋芽孢杆菌(Bacillus marinus)B-9987菌株抑制病原真菌机理

目的]探讨海洋芽孢杆菌(Bacillus marinus)B-9987菌株的代谢产物BMME-1,对植物病原真菌茄链格孢菌的抑菌作用机理.方法]分别使用分光光法、气相色谱-质谱GC-MS联用技术、红外光谱法等,检测了BMME-1处理病原真菌后,菌体渗透性、细胞壁及细胞膜成份的变化.结果]BMME-1对茄链格孢菌的抑菌中浓度(MIC_(50))为6.2 mg/L,最小杀菌浓度(MFC)为50 mg/L,在MIC_(50)浓度或高于此浓度处理靶标菌,将导致菌体蛋白质、核酸等大分子物质的外流;处理菌株葡聚糖结构β-型糖苷键、碳-氧键(C-O)、碳-氢键(C-H)等基团的特征吸收强度降低,-OH、C=O的伸缩振动吸收强度升高;菌体细胞壁几丁质结构中酰胺I键吸收强度发生变化;与对照菌株的麦角甾醇含量(62.52±3.31%)相比,处理菌株麦角甾醇减少为(56.36±2.52)%,同时出现麦角固醇合成中间产物粪甾醇.结论]BMME-1对病原真菌的抑制表现为:干扰细胞膜麦角甾醇的合成从而改变了细胞的通透性;对细胞壁葡聚糖结构的影响较大而几丁质次之.

Antifungal mechanism of Bacillus marinus B-9987

Objective] We studied the antifungal effect of the metabolite BMME-1 from Bacillus marinus B-9987, to reveal its antlfungal mechanism. Methods] The permeability of the Alternaria solani was tested by spectrophotometer after the treating the crude extracts of B-9987. The composition of cell wall and the sterol components of the fungal plasma]emma of Alternaria solani were analyzed with Infrared Spectrum and GC-MS, respectively. Results] We found that the metabolites of B-9987 had strong antifungal activity with MIC_(50) and MFC value being 6.2mg/L and 50mg/L. The absorhance in extracellular fluid detection showed that the tegument of the fungi was impaired. The detection of glucan and chitin indicated the change in the structure of the cell wall. The absorption peak of the carbon-hydrogen bond, β-glucosidic bond, carbon-oxygen bond was attenuated but the hydroxyl, carbenyl absorption was enhanced on the contrary. There were only one peak change in chitin chromatogram on the absorption of amide linkage comparing to the control. These changes on the structure may affect the stability of the fungal cell wall. Ergosterol was the predominant component of sterol with the proportion of 62.52±3.31% in control cells, but showed a decline during treatment with BMME-1 at a concentration of 56.36±2.52%. Accumulation of coprostanol, the precursor of ergosterol,was found in the test. Conclusion] From the result we can conclude that the antifungal mechanism of the crude extracts was interfering of ergosterol synthesis resulting in the change on permeability, and also mainly changed the structure of the cell wall, mainly acting on the glucan synthesis.