中文摘要：

【目的】明确枯草芽孢杆菌Bs916（Bacillus subtilis 916）分泌的脂肽化合物Bacillomycin L操纵子、结构和生物活性,阐明枯草芽孢杆菌Bs916防治病害的分子生化机制。【方法】采用LA-PCR和基因步行的方法克隆bacillomycin L的操纵子Bac;通过生物信息学的方法分析Bac操纵子的遗传特征;运用基质辅助解离质谱法测定Bac操纵子合成的脂肽类化合物bacillomycin L的分子量;利用碰撞诱导解离（CID）技术获得化合物的典型结构特征离子碎片测定bacillomycin L肽端的一级结构;通过平板对峙实验和溶血活性试验测定bacillomycin L的生物活性。【结果】克隆到全长约39.0kb的Bac操纵子,该操纵子由BacD、BacA、BacB和BacC4个多功能复合酶及1个启动子组成;生物信息学分析表明Bac操纵子与脂肽类化合物iturinA、mycosubtilin、bacillomycin D操纵子具有很高的同源性,然而也发现一段低同源性区域,该区域是一个新型Ser激活结构域。根据Bac操纵子特征推测Bac操纵子编码的脂肽类化合物可能是Bacillomycin L;Bac合成的脂肽类化合物的分子量分别为：1008,1022,1036和1050Da;推测属于相差一个（-CH2）亚甲基的同系物;脂肽化合物的一级结构为[cyclo-（Asn-Tyr-Asn-Ser-Glu-Ser-Thr-β-amino fattyacid）],该一级结构与以前报道的bacillomycin L的肽序列一致。生物活性测定结果表明其是一种生物表面活性剂,具有广谱抗真菌活性。【结论】本研究克隆了bacillomycin L的完整操纵子,并通过对操纵子生物信息学分析和生化试验鉴定了枯草芽胞杆菌Bs916分泌的脂肽bacillomycin L的化学结构,并阐明了生防菌Bs-916分泌的脂肽bacillomycin L是其抗真菌活性的关键因子。

英文摘要：

【Objective】The aim of this study is to clone and sequence the Bac operon responsible for synthesis of the bacillomycin L from Bacillus subtilis Bs916 and determine the structure and biological activities of the bacillomycin L. 【Method】 LA-PCR and gene walking were performed to clone the Bac operon responsible for synthesis of bacillomycin L. Analysis of the Bac operon genetic structure was made using bioinformatics. The molecular weight of the bacillomycin L homologues was determined by matrix-assisted laser desorption ionization-time of flight mass spectrometry （MS）. ESI/MS-CID was used to determine the bacillomycin L peptide moiety primary structure. 【Result】 The 39.0 kb Bac operon responsible for synthesis of bacillomycin L was identified and cloned from Bacillus subtilis Bs-916. The operon contained a promoter and four ORFs and the four ORFs designatedBacD, BacA, BacB, and BacC, respectively. Although the amino acid sequences encoded by the Bac operon share high similarity with the countpart amino acid sequences encoded by itu, myc and bam operons, a low similarity region was also found and it presumed to be a novel Ser activation domain. According to the Bac sequence, the lipoepeptide presumed to belong to bacillomycin L. The molecular weights of the bacillomycin L were 1 008,1 022,1 036 and 1 050 Da. They were presumed to belong to homologues differed by a structure of -CH2. The bacillomycin L peptide moiety primary structure was [cyclo- （Asn-Tyr-Asn-Ser-Glu-Ser-Thr-β-amino fatty acid）] and it is the same as the peptide sequence of bacillomycin L reported previously. In vitro tests to pathogenic fungi indicated that bacillomycin L have a broad antifungal activities and hemolytic activities. 【Conclusion】This paper reported the cloning, sequencing and characterization of a whole operon Bac which is responsible for synthesis of bacillomycin L. Through bio-information and chemical analysis, the authors also further confirmed the primary structure of bacillomycin L which has paradox repo