由大丽轮枝菌（Verticillium dahliae Kleb）引起的棉花黄萎病，是一种危害严重的世界性病害。通过初筛和复筛得到了对棉花黄萎病具有较高拮抗活性的细菌菌株12-51，通过对其进行形态鉴定、生理生化特征鉴定和16S rDNA全序列分析，最终鉴定此菌株为Bacillus velezensis，16S rDNA序列相似度达99.74%。采用有机溶剂萃取和盐析法对发酵产物进行了提取，初步断定拮抗物质为蛋白类。通过对粗蛋白进行进一步研究发现，60%组分活性较高，并且对热以及酸碱敏感性较小。试验结果为棉花黄萎病的生物防治奠定了基础。

Cotton Verticillium wilt, which is caused by Verticillium dahliae kleb is a worldwide disastrous plant vascular disease. Bacteria strain 12-51 with a rather higher antagonistic activity was obtained after primary and secondary screening. The morphology characteristics, physiological and biochemical properties and 16S rDNA sequence of this strain were studied. The similarity of the 16S rDNA sequences between bacteria strain 12-51 and Bacillus velezensis were up to 99.74%. So, the strain 12-51 was finally identified as Bacillus velezensis. It was determined preliminarily that the extracts were proteins by analyzing the antifungal activity of the extracted substance through organic solvent extraction and salting-out method against Verticillium dahliae Kleb. The results showed that the component of 60% extracted substance had the biggest inhibition zone and the antifungal protein was not sensitive to the heat and pH value. The results laid the foundation for the biological control of Cotton Verticillium wilt.