嗜线虫致病杆菌YL001抑菌活性成分及其产量影响因素的研究
Antimicrobial Active Constituents and Its Yield Influencing Factors of Xenorhabdus nematophilus YL001

采用硅胶柱层析等分离方法，结合MS与NMR技术，对嗜线虫致病杆菌YL001发酵产物中的抑菌活性成分进行分离鉴定；采用微量稀释法对Nematophin的抑菌活性进行测定；利用HLPC分析不同因素对Nematophin产生的影响。结果表明，分离得到主要抑菌活性物质 Nematophin，并鉴定其结构为3-吲哚乙基（3′-甲基-2′-酮）戊酰胺，其对革兰氏阳性菌具有较好的抑菌活性；不同菌株发酵产物中Nematophin的产量不同，其中YL001菌株的产量最高，为115.23 μg/mL；Nematophin产量在初始pH 4.5~8.5逐渐升高，初始pH 8.5时最高，为155.08 μg/mL。发酵罐培养条件下Nematophin的产量高于摇瓶，且在初始pH 8.5时达到最高，为206.97 μg/mL。主要抑菌活性物质与文献报道的 Nematophin相同，昆虫病原线虫共生菌次生代谢物的产生与菌种、菌株及培养条件密切相关。
The active ingredients from fermentation broth of Xenorhabdus nematophilus YL001 were isolated and purified by column chromatography and other extraction process, and their structures were identified by MS and NMR spectra.The minimal inhibitory concentrations (MIC) against bacteria of the purified Nematophin were detected by broth dilution technique.Analyzing the yield influencing factors of Nematophin by using HPLC.The factors related to Nematophin production, including different strains of the same species and culture conditions, were also explored.The results showed that one antibacterial ingredient was isolated from fermentation broth of Xenorhabdus nematophilus YL001 and identified as Nematophin with a chemical name of 3-indoleethyl (3′-methyl-2′-oxo)pentanamide which possesses significant activity against Gram-positive bacteria.The output of Nematophin was different from Xenorhabdus neamatophila strains, and the highest yield of Nematophin was obtained from YL001 strain, which was 115.23 μg/mL.The yield of Nematophin increased in the range of initial pH 4.5 to pH 8.5, and the highest yield, 155.08 μg/mL, was obtained at pH 8.5.The yield of Nematophin was higher in fermentation tank than in the Erlenmeyer flask, and the highest yield,206.97 μg/mL, of Nematophin was obtained in fermentation tank at pH 8.5.In conclusion, the main ingredient in Xenorhabdus neamatophila was designated as Nematophin identified by former documents, the secondary metabolites of the insect pathogenic nematode symbiotic bacteria is closely related to the bacteria, strain, and the cultured conditions.