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- 2018
枯草芽胞杆菌MG-4抑制小麦全蚀病菌物质及其性质分析
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Abstract:
为明确本实验室筛选并鉴定的枯草芽胞杆菌Bacillus subtilis菌株MG-4分泌物对小麦全蚀病菌的抑制作用及其性质，采用生长速率法检测了菌株MG-4发酵菌上清液（cell-free supernatant，CFS）中抑菌物质的稳定性，并通过PCR扩增抑菌物质合成相关基因，利用基质辅助激光解吸飞行时间质谱鉴定抑菌物质结构。结果表明，菌株MG-4分泌的抑菌物质在中性及酸性条件下稳定，在pH 2~7时CFS相对活性为98.8%~100.0%；热稳定性强，100℃处理30 min后相对活性仍为88.5%；利用胃蛋白酶和胰蛋白酶处理120 min后相对活性为98.8%；CFS中抑菌物质不能被氯仿、乙醚和乙酸乙酯萃取，且对这3种有机溶剂不敏感；Na+、K+、CO32-和I-对CFS活性影响，Mg2+、Ca2+、NO3-、SO42-、H2PO42-和Mn2+显著抑制CFS活性。菌株MG-4基因组中含有srfAB、yndJ、bamC、fenD、ituC和ituD共6种抑菌物质合成基因；将菌株MG-4分泌的抑菌物质鉴定为C14~C15伊枯草菌素A、C14~C18芬荠素A和C14~C17芬荠素B。
To identify the properties of antifungal substances of biocontrol bacterium Bacillus subtilis MG-4, the stability of MG-4 culture cell-free supernatant (CFS) were detected though the growth rate method, the genes related to the synthesis of antifungal substances were amplified using PCR, and the composition of the antimicrobial substance was identified using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS). The results showed that the antifungal substance was stable in acidic and neutral environment and remained 98.8%-100.0% of the relative activity in pH 2-7. Meanwhile, MG-4 CFS was relatively thermally stable with 88.5% of the antifungal activity after heated at 100℃ for 30 min. The relative activity remained 98.8% when CFS treated with pepsin and trypsin for 120 min. The antifungal substance was not transferred to the organic solvent phase and the activity did not decrease after treated with organic extraction agents of ether, ethyl acetate and chloroform. The activity of the antifungal substance was not significantly affected by Na+, K+, CO32-, and I- but significantly inhibited by Mg2+, Ca2+, NO3-, SO42-, H2PO42-, Mn2+. The genome of MG-4 strain contain six kinds of antibiotic synthesis genes including srfAB, yndJ, bamC, fenD, ituC and ituD. The antifungal substances include C14-C15 iturin A, C14-C18 fengycin A and C14-C17 fengycin B.
