Screening And Identification Of Antagonistic Endophytic Bacteria Against Banana Fusarium Wilt And Study On Its Biological Control Characteristics

63endophytic bacterial strains were isolated and purified from the healthy banana plants, in which2antagonistic bacterial strains among them screened with slab confrontation method, had fairly strong inhibition effect to Bananas Fusarium wilt. They were identified as Bacillus subtilis based on the morphological, physiological and biochemical properties, and the16S rDNA sequence analysis.It has been demonstrated that the fermentation filtrates of strain HZY-23had the inhibition to FOC4. Different concentrations of fermentation filtrates can inhibit spores germination and growth of pathogen effectively.With the increase of concentration of fermentation filtrates, inhibition effect are enhance. Spores was inhibited from no inhibition to slight inhibition, moderate inhibition, and high inhibition. The end of hyphae are enlargement, hyphae rupture and branches.Different concentrations of fermentation filtrate for Bananas Fusarium wilt potted seedlings control effect test results show that the concentration is70%,50%,30%had no significant differences. The control effect of30%concentration of fermentation filtrates can achieve good control effect.Using different processing method research strains HZY-23control effect of Banana Fusarium wilt.The test results show that the best control effect is spraying the fermented filtrates before the inoculation of pathogenic bacteria.It had been obtained300μg/mL rifampicin resistance marked strain after HZY-23being induced. The marked strain can into the banana plant tissue, and in which colonization. On the whole, the number of marked strain in banana plant is to reduce first,and then add, finally to reduce to a state of relative stability along with the time.Researchs on fermentation conditions of Bacillus subtilis strain HZY-23on single-factor experiment basis have been done.Four important factors of glucose, ammonium chloride,temperature and pH,which can influence the living bacteria amount,were screened through Plackett-Burman design and test.The results showed that the optimal fermentation condition was glucose0.98%, ammonium chloride0.87%,calcium chloride0.5%, fermentation temperature31.09℃, pH7.11, shaking speed150r/min, fermentation time36h, inoculation size1%by using the steepest ascent path, Box-Behnken design and response surface analysis.Under the optimal fermentation condition,the living bacteria amount of fermentation broth can reach2.9*109CFU/mL.In order to improve the endospores yield of HZY-23,the single factor test was made to optimize the medium components and the fermentation conditions of HZY-23.Three important factors of corn meal, soybean cake powder and MgSO4,which can influence the endospores yield,were screened through Plackett-Burman design and test.The results showed that the optimal fermentation condition was corn meal1.115%, soybean cake powder1.115%,sodium chloride0.5%, MgSO40.06%, pH7, shaking speed150r/min, fermentation temperature30℃, fermentation time48h by using the steepest ascent path,center combination of design and response surface analysis.Under the optimal fermentation condition,the endospores yield of HZY-23achieved6.6*108CFU/mL.