Identification of Bacterial Wilt Antagonistic Bacteria JK19 and Detection of Its Antibacterial Activity

【Objective】 To clarify the taxonomic status of antagonistic bacterium JK19, detect its antibacterial activity, and analyze its possible active components. The results provide theoretical basis for the extraction of lipopeptide and the development of biological control agents . 【Methods】 The strain was identified by morphological, physiological and biochemical characteristics and 16S rDNA sequence analysis. The antagonistic effect of the strain against 8 plant pathogens was detected by plate confrontation method. PCR amplification was used to detect the genes related to the synthesis and probiotics of lipopeptide antibiotics in the genome. 【Results】 JK19 was identified as bacillus by morphological, physiological and biochemical characteristics, and 16S rDNA sequences of JK19 were compared to construct a developmental tree. It was found that JK19 had close homologous relations with Bacillus velezensis, Bacillussiamensis and Bacillus amylobacillus. Strain JK19 had significant inhibition effect on various plant pathogens, and the inhibition effect was 66.67% for black spot of fragrant pear, 100% for walnut rot, 73.33% for potato early blight, 60.71% for watermelon blight, 67.86% for rice blight, 76.92% for cotton blight and 100% for watermelon vine blight, respectively. PCR reaction detected the genes involved in the synthesis of lipopeptide antibiotics in JK19 genome: ituA, ituD, bamC, fenB, fenD, srfAB, YsnE, a gene involved in the synthesis of auxin IAA and geneyndJassociated with probiotics. 【Conclusion】 Antagonistic bacterium JK19 is abacillussp., which has obvious inhibitory effect on various plant pathogenic bacteria such as tomato bacterial wilt, and its genome contains lipopeptide and genes related to probiotics.