The Screening and Identification of Antagonistic Bacterium Strain HD-5 against Watermelon Fusarium Wilt

In order to obtain antagonistic bacteria against Fusarium oxysporum Schl.f.sp.niveum,84 strains were isolated and screened with the improved agar plate diffusion method using the soil form different districts.The antagonistic activity of strains against F.oxysporum Schl.f.sp.niveum was tested via secondary screening.As a results,strain HD-5 showing the strongest antagonistic activity against F.oxysporum Schl.f.sp.niveum was obtained.Thus the morphology characteristics,physiological and biochemical properties and 16 S rDNA sequence of this strain were studied to determine the species.The similarity of the 16 S rDNA sequences between strain HD-5 and Bacillus subtilis were up to 99.78%.Finally,the strain HD-5 was identified as Bacillus amyloliquefaciens.