Screening,identification and biocontrol effect of antagonistic bacteria against banana Fusarium wilt

【Objective】 The aim was to screen and obtain antagonistic strains against banana Fusarium wilt, and provide strain resources for biological control of banana Fusarium wilt.【Method】 The banana rhizosphere soil was used as the material to screen the strains that could secrete siderophores and had antagonistic effect on Fusarium oxysporum f sp.cubense by using chromeazurol S(CAS) double-layer plate and plate confrontation method. The antagonistic activity of antagonistic strains against six common plant pathogenic bacteria was determined by plate confrontation method. The taxonomic status of the antagonistic strains was clarified through physiological and biochemical determination and 16 S rDNA sequence analysis. The pot experiment was conducted to verify the efficacy of the antagonistic strains against banana Fusarium wilt and their growth-promoting effects on banana plants.【Result】 After initially screened with CAS medium, 60 strains secreting siderophores were screened out from the soil, and five strains were selected out of them by plate confrontation method. Among them, Gxun-2 had the highest bacteriostatic rate, reaching 74.45%, and had fine inhibitory effect on the other six plant pathogens tested, with broad-spectrum antibacterial property. Combined with colony morphology, physiology and biochemistry and 16 S rDNA phylogenetic tree analysis, Gxun-2 was identified as Pseudomonas aeruginosa. Pot experiment showed that the strain had obvious disease prevention effect on banana Fusarium wilt with the control effect reaching 84.21%. It had certain growth promoting effect on banana plants, the fresh seedling weight increased by32.96%.【Conclusion】 Gxun-2 strain has a strong effect on preventing and treating banana wilt, and promoting growth of banana seedlings, and can be used as a candidate strain resource for development of candidate strain resources for biological control of banana Fusarium wilt.