| Cotton Verticillium and Fusarium wilts are common plant diseases, and hard to be controlled. They cause serious damage to the world economy. It is urgent to isolate the antagonistic bacteria and develop the biological pesticides to control the diseases. In this research, we screened 5 antagonistic bacteria which can strongly inhibit Verticillium wilt pathogen and Fusarium wilt pathogen, and then cloned the resistance-related gene.21 bacteria were Isolated from cotton land rhizosphere soil from The Plant Protection Institute of The Chinese Academy of Agricultural Sciences. And 5 of them can strongly inhibit Verticillium wilt pathogen and Fusarium wilt pathogen. The antibacterial efficiency of fermentation broth of C5, C6, S6, S1, B1 are about 22.6%, 38.7%, 53.1%, 52.4% , 21%(against Verticillium wilt pathogen), and 22.8%, 38.7%, 55.2%, 56%, 23.5% (against Fusarium wilt pathogen). The strain S6 and S1 can be develop as biological pesticides.All of the 5 antagonistic bacteria are positive bacteria. S6 was identified as Bacillus sp. by the method of 16s rDNA. S6 grows very fast. It grows well in the temperature between 15℃and 50℃, the optimum temperature is 28℃; it also grows well in the pH between 4 and 9, the optimum pH is 7.S6 couldn't resistance to the antibiotic of Amp,Cm,Ery,Rif,Km, but can weak resistance to the concentration of 25μg/mL of Spc and Sm. It shows that the antibiotic components including the volatile component and the cell wall-degrading enzyme. The activity of the chitinase is 6.04U; the glucanase is 24.86U; the pectinase is 23.37U; the cellulase is 10.37U.The glucanase is an important antifungal protein. With specific primers designed, 700bp PCR product was amplified, the fragment was sequenced and closed related to glucanase with 69%. Constructing mutation library of S6 by pIC333, 3 mutations were isolated. One of the them was sequenced, and the sequences are closely related to iturin A synthetase B with 99%.
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