中文摘要：

【目的】明确枯草芽胞杆菌Bs916（Bacillussubtilis916）分泌的脂肽化合物Fengycin操纵子的结构、功能和生物活性，阐明枯草芽孢杆菌Bs916防治真菌病害的分子作用机制。【方法】在Bs916全基因组测序基础上，采用LA-PCR方法克隆Fengycin的操纵子Fen；通过生物信息学方法分析Fen操纵子的遗传特征；运用基质辅助解离质谱法测定Fen操纵子合成的脂肽类化合物中同系物的分子量；采用同源重组方法构建Fengycin突变株BSFG；通过抑菌活性和溶血活性试验测定突变株BSFG的生物活性。【结果】克隆到Bs916基因组DNA中全长约37．67kb的Fen操纵子，含有5个开放阅读框架分别编码FenA、FenB、FenC、Fend和FenE多功能复合酶；与Bsl68对应Fen操纵子的同源性为65％。根据该操纵子特征推测其编码的脂肽类化合物为Fengycin；Fen操纵子负责合成的Fengycin包含5个变异体，分属于两类不同同系物。同系物1的质子化峰分子量分别为1449．8、1463．9、1477．9；属于相差1个（-CH2）亚甲基的同系物，一级结构为[cyclo-（[cyclo-（Glu-Orn—Tyr—Thr—Glu—Ala—Pro—Gin—Tyr-β-aminofattyacid）]；同系物2的质子化峰分子量分别为1491．9和1505．9，也属于相差1个（-CH2）亚甲基的同系物，相对于同系物1其第6位的A1a氨酸残基变为Val氨酸残基。生物活性测定结果表明突变株BSFC抗菌活性相对于野生型菌株Bs916得到显著下降，但溶血活性的变化不明显。【结论】本研究克隆了生防菌Bs916中合成Fengycin的完整操纵子，通过对操纵子生物信息学分析和生化试验鉴定了Fengycin的5种变异体的化学结构，并阐明了脂肽Fengycin是Bs916抗真菌活性的重要因子之一。

英文摘要：

[ Objective ] The objective of this study is to clone and sequence the Fen operon responsible for synthesis of the fengycin from Bacillus subtilis 916 and determine the structure and biological activities of the Fen operon. [Method] Genome sequence and PCR were performed to clone the Fen operon. Analysis of the Fen operon genetic structure was made by using bioinformatics. The Fen mutant BSFG was constructed by the homologous recombination. Fengycin produced by the Bs916 and mutant was analyzed by the reversed-phase high-performance liquid chromatography （HPLC）. The molecular weight of the fengycin was determined by the matrix-assisted laser desorption ionization-time of flight mass spectrometry （MS）. The antifungal activities and hemolytic activities were evaluated in the form of a flat plate. [Result] The 37.67 kb Fen operon responsible for synthesis of fengycin was identified and cloned from B. subtilis 916. The operon contained five ORFs designated FenA, FenB, FenC, FenD and FenE, respectively. The amino acid sequences encoded by the Bs916 Fen operon share 65% similarity with the counterpart amino acid sequences from the Bs168 Fen operon. The results of HPLC analysis of lipopeptides produced by wild-type Bs916 and mutant BSFG showed the Fen operon responsible for fengycin synthesis. The molecular weights determined by MS were 1 449.8, 1 463.9, 1 477.9 and 1 491.9, 1 505.9 Da showed fengycin produced by Bs916 contained five homologues. The first three homologues were differed by a structure of ~[~H2 and their peptide moiety primary structure were [cyclo-（[cyclo-（Glu-Om-Tyr-Thr-Glu-Ala-Pro- Gln-Tyr-fl-amino fatty acid）]. The last two homologues were also differed by a structure of-CH2 and their peptide moiety primary structure were Val （6） instead Ala （6） compared to homologues above. Although the mutant BSFG decreased clearly in antifungal activities, its hemolytic activities showed no obvious difference compared to wild type Bs916. [Conclusion] This paper reported the cloning, sequencing