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从浙江省金华市郊水稻内生菌中筛选到1株拮抗水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)P6生理小种的淡色生赤壳菌Bionectria ochroleuca Bo-1菌株。该菌株的菌体和发酵液对Xoo P6生理小种均表现出较强的拮抗能力。以P6生理小种作为指示菌进行活性跟踪,通过分步萃取、硅胶柱层析、高效液相色谱等,分离纯化获得拮抗活性物质结晶;对所获得的结晶物进行核磁共振氢谱分析和质谱分析,通过解析与比对,该物质分子量为344.0835,分子式为C_(18)H_(16)O_7,鉴定为松萝酸(usnic acil)。将纯化的松萝酸以20%叶枯唑(bismerthiazol)和3%中生菌素(zhongshengmycin)为对照,采用96孔板法测定对Xoo P6生理小种的抑菌活性,最低抑制浓度为200μg/mL,表明松萝酸具有较强的抑菌活性,但较中生菌素弱,与20%叶枯唑效果相近。
A strain of Bionectria ochroleuca Bo-1 antagonistic to Xanthomonas oryzae pv. Oryzae (Xoo) P6 physiological race was screened from rice endophytes in the suburbs of Jinhua, Zhejiang Province. The strain of bacteria and fermentation broth Xoo P6 physiological race showed strong antagonistic ability. P6 physiological race as an indicator of activity tracking, by step extraction, silica gel column chromatography, high performance liquid chromatography and other isolated and purified to obtain antagonist active substance crystals; obtained by crystallization of the product by 1H nuclear magnetic resonance spectroscopy and mass spectrometry Through the analysis and comparison, the molecular weight of this material is 344.0835 and the molecular formula is C 18 H 16 O 7, which is identified as usnic acil. The purified usnic acid was tested for its antimicrobial activity against Xoo P6 physiological races using 20% bismerthiazol and 3% zhongshengmycin as 96-well plates with a minimum inhibitory concentration of 200 μg / mL, indicating that usnic acid has strong antibacterial activity, but weaker than mesenchymal, and 20% similar effect of leaf furazole.