Isolation,identification and biocontrol effect of antagonistic bacteria against Fusarium oxysporum f.sp.cubense

In this experiment,sixteen antagonistic strains against Fusarium oxysporum f.sp.cubense(FOC)were screened from banana rhizosphere soils collected from the experimental plot of banana in Hainan Province.One of the isolated strains,YL-19,which showed the strongest antifungal activity,was selected for the further study.The diameter of its inhibition zone against FOC was above 26.26 mm.According to the observations of morphological characters,physiological and biochemical tests,and 16S rDNA sequence analysis,the strain YL-19 was identified to be Bacillus sp.The optimal growth temperature and pH was 37-42 ℃ and 6-8,respectively.The antibacterial substances in the fermentation broth of YL-19 were resistant to trypsin,ultraviolet radiations and base,but sensitive to acid,base and heat.Pot experiment showed that the application of bioorganic fertilizers made of YL-19 at the seedling stage of banana could decrease the disease incidence of FOC by 74%,compared with control,and had significant growth-promoting effect on banana plants.