Screenning Of Antagonistic Bacteria And Purification For Antifungal Protein

This paper presents a study on the biological control of cotton disease Verticillium wilt by antagonistic bacteria including the isolation, screening of antagonistic bacteria and purification for an antifungal protein.148 strains bacteria were isolated from cotton plant microecosystem. The antagonistic assay in plates showed that among them there were 38 strains which had antagonistic activity to Verticillium dahliae. LC105 had the highest antagonistic activity.Proteins were precipitated from ferment solid production of LC105 and they had the antagonistic activity to Verticillium dahliae. The antagonistic activity of the proteins were lost after were treated by heat and CHCl3. This showed that the antifungal material must be protein.We cultured LC105 strain under different conditions and studied the antagonistic activities of the solid ferment production. The assay showed that the strain could serecte lots of antifungal protein under 30℃ degree, in LBG medium of pH 7 and cultured 48 hours.With (NH4)2S04 fractional precipitation, DEAE-Sephadex A-50 ion exchange chromatography and Sephacryl S-300 molecular filtration chromatography followed by tracks of fraction antagonistic assay and PAGE, an antifungal protein with in vitro antagonistic activity to Verticillium dahliae was isolated and purified.