苏云金芽胞杆菌抗菌脂肽初步鉴定及抑菌活性测定

植物枯萎病是影响作物生长的重要因素，利用植物内生菌拮抗病原菌生长，从而降低其危害程度是目前研究的热点。本研究从健康的番茄植株中筛选分离得到一株对番茄枯萎病病原菌有较强拮抗作用的内生细菌B-R1,通过形态学、生理生化以及分子生物学检测分析，鉴定该菌株为苏云金芽胞杆菌(Bacillus thuringiensis)。为进一步探索该菌株的生防作用，首先将菌株发酵后离心，得到发酵上清液，采用盐酸沉淀法对其活性物质进行粗提，并检测其对大肠埃希菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)以及尖孢镰刀菌(Fusarium oxysporum)的抑菌活性。通过薄层色谱法(TLC)、傅里叶红外光谱(FI-TR)、高分辨液相色谱-质谱联用仪(LC-MS)分析并鉴定活性物质的结构。结果表明，苏云金芽胞杆菌对尖胞镰刀菌有良好的抑制作用，结构分析初步鉴定抗菌物质中含有丰原素(fengycin),属于脂肽类抗生素。

Preliminary Identification and Antibacterial Activity of Antibacterial Lipopeptide from Bacillus thuringiensis

Plant fusarium wilt is an important factor affecting the growth of crops. The use of plant endophytes to antagonize the growth of pathogenic bacteria, thereby reducing the degree of harm, is a hot research topic at present. An endophytic bacterium B-R1 having strong antagonistic effect against the pathogen of tomato Fusarium wilt, was isolated from healthy tomato plants in this experiment. The strain was identified as Bacillus thuringiensis adopting morphological, physiological, biochemical and molecular biological analyses. In order to further explore the biocontrol effect of the strain, the fermentation supernatant was obtained by centrifugation after fermentation, and the active substances were crudely extracted by hydrochloric acid precipitation method. The antibacterial activity against E. coli, Staphylococcus aureus and Fusarium oxysporum was detected. The structures of the active substances were analyzed and identified by thin layer chromatography (TLC), Fourier transform infrared spectroscopy (FI-TR) and high resolution liquid chromatography-mass spectrometry (LC-MS). The results showed that B. thuringiensis had good inhibitory effect against Fusarium oxysporum. Structural analysis initially identified that the antibacterial substance contained fengycin, which belonged to lipopeptide antibiotics.