枯草芽孢杆菌F-2抗植物病原真菌活性物质的研究

Study on antifungal active substance of Bacillus subtilis F-2.

枯草芽孢杆菌F-1和F-2与尖孢镰刀菌的对峙实验中,F-1没有抑菌作用,而F-2表现出强抑菌效果.为了分析测定F-2的抑菌活性物质,对F-1和F-2胞外代谢物粗提液的HPLC谱图进行比较,发现F-2具有F-1所没有的特征代谢产物.使用LC-MS对F-2的特征产物进行分析,推测主要产物的分子量为1477.0、1489.1和1505.1.进一步采用MALDI-TOFMS对F-2粗提液进行分析,发现F-2产生两组分子量相差14Da(CH2)的同系物.其中一组的分子量依次为1462.8、1476.8、1490.8、1504.8和1518.9,通过质量指纹谱技术鉴定为脂肽抗生素C14-18 Fengycin B.另一组的分子量依次为1432.8、1446.8、1460.8、1474.8和1488.9,与C14-18 Fengycin A对应分子分子量相差2Da,推测可能是Fengycin A的一种异构体,其碳链中具有一个双键,具体性质有待进一步分析.

Effects of Bacillus subtilis F-1 and F-2 on inhibiting the growth of Fusarium oxysporum f, sp. cucumerinum （F.o. c） were studied by a co-culture experiment. The results showed that the growth of F. o. c could be strongly inhibited by the specific metabolites of Bacillus subtilis F-2, but not by Bacillus subtilis F-1. It was guessed by LC-MS determination that the possible molecular weights of the specific metabolites were 1477.0, 1489.1 and 1505.1. It was further found by MALDI-TOF MS that there were two groups of homologues with a difference of 14 Da in molecular weights in the extract of Bacillus subtilis F-2. In the first group, there were 5 kinds of homologues with the molecular weights of 1462.8, 1476.8, 1490.8, 1504.8 and 1518.9, respectively, which were identified as lipopeptide antibiotics Fengycin B（C14-18 ） by the method of mass fingerprinting. In the second group, the molecular weights of 5 kinds of homologues were 1432.8, 1446.8, 1460.8, 1474.8 and 1488.9, respectively, which were estimated as the isomer of Fengycin A（C14-18） as only 2 Da difference in molecular weights.