Isolation and Preliminary Identification of Antagonistic Bacterium against Fusarium wilt of Cucumber and Watermelon

To screen and isolate the antagonistic bacteria that can control cucumber and watermelon wilt pathogen Fusarium oxysporum from the soil,the antagonistic bacteria from soil samples in the greenhouse where pepper was planted and could antagonize cucumber and watermelon wilt pathogen Fusarium oxysporum were conducted for the plate confrontation experiment.The results showed that,LX6,LX7,LX12,LX13 bacterial strains could antagonize Fusarium oxysporum of cucumber and watermelon and had clear inhibition zone;the inhibition zone diameter arrived at 19.3,18.2,17.4,25.5 mm and 16.2,15.0,15.9,14.8 mm after 96 h.In a 30-day-pot-test,control rates against F.oxysporum of LX6 strain treated in cucumber and watermelon were 85.3 % and 81.2 %,respectively.The results of plate culture,microscopy,16S rDNA-based molecular identification(1650bp fragment) and physiological and biochemical characterization showed that the isolated antagonistic bacterium was Bacillus amyloliquifacience and its molecular weight of 16sDNA fragment was 1650 bp.