Colonization And Biocontrol Potential To Fusarium Wilt Of Banana Of Siderophore-producing Endophytic Bacteria Beb99

In this study, effects of enzyme activity were elucidated in the inoculated banana plants by analyzing colonization patterns of siderophore-producing endophytic bacteria BEB99. The growth-promoting function and biocontrol effect of strain BEB99were evaluted in banana plant. And the petroleum ether crude extract was extracted from BEB99fermented product, and analyzed by GC-MS. As well as, the antagonistic mechanisms of activity metabolism product of BEB99strains for Fusarium oxysporium were studied. The results are as follows:The antagonistic bacteria strain BEB99was inoculated back into banana plants by using root-irragating methods. The analysis result of sampling at different times indicated that Rif-resistant mutants could be recovered from leaves, stems and roots of banana plants inoculated by the method. It was suggested that the strain BEB99could colonize, move and reproduce in the banana plants.For elucidate the mechanisms underlying the disease prevention effects of endophytic bacteria strain BEB99, the activities of five protective enzymes including POD, SOD, PAL, PPO and CAT were respectively determined in banana plants treated with the suspension of Fusarium oxysporum and endophytic bacteria strain BEB99. The results revealed that PAL and PPO were significantly high in treatment with the suspension of strain BEB99compared with control, but POD, CAT and SOD activity had no change. This indicated that treatment with the suspension of strain BEB99could induce some protective responses of banana plants.In pot experiment, banana plants were inoculated by irrigateing the cell cultures of the antagonistic bacteria. The results revealed that the strain BEB99could significantly enhanced the control efficacy against Fusarium oxysporum f.sp.cubense in banana. The treatment inoculating pathogen7days after the strain BEB99inoculation showed the best control efficacy that reached to61.94%. The control efficacy of strain BEB99decreased to32.05%if they were inoculated7days after pathogen inoculation. The antagonistic mechenisms of strain BEB99might cause the result. The first, the abundant antagonistic bacteria occupied the entry points of pathogens. The second, some metabolites of the antagonistic bacteria might have inhibitory effects on pathogenes and could induce defense responses of host plants. Pot experiments also revealed that the strain could significantly promoted the growth of banana plants.Nineteen ingredients were identified from the petroleum ether crude extract of BEB99by GC-MS analysis. There were6kinds Ester,9kinds acids,2kinds aldehydes among them. The relative content of Oleic acid, Ethyl linoleate, Linoleic acid, Ethyl linoleate, Palmitic acid and Ethyl palmitate were higher than others.The petroleum ether and ethyl acetate crude extracts of endophytic bacteria strain BEB99were got by solvent method, and were tested by agar disc diffusion method for their antimicrobial activities against Fusarium oxysporum. The results revealed that the pathogenic hyphae grew in abnormal shape and produced sac.The inhibition rate were92.99%and82.96%respectively when the concentration of petroleum ether and ethyl acetate crude extracts reach to1.67mg/mL. The antagonistic mechanisms of ethyl acetate crude extract of BEB99strains for Fusarium oxysporium were studied by biological chemical method. The results revealed that ethyl acetate crude extract could influence lipid peroxidation, ergosterol content, protein content, the aetivity of PMG and Cx of Fusarium oxysporum. But it could not decompose the chitin.