Isolation、Identification Banana Plant Endophyte BEB33and Study On Its Growth Promoting And Biological Control

49endophytic bacterial strains were isolated from healthy banana roots from banana wilt disease fields at Ledong, Lingao, Chenmai, Baisha and Danzhou cities in Hainan province. Fusarium wilt of banana (FOC4) was used as target pathgen. BEB33, an endophytic bacteria with strong antibacterial activity was isolated. Based on the morphological, physiological and biochemical characteristics, and sequences analysis of16S rDNA and recA, it was initially identified as Bacillus amyloliquefaciens, named BEB33.Pot experiment revealed that the strain BEB33could significantly promote the growth of banana plants, the growth rate were40.21%after30days and37.07%after60days. The promoting mechanism of strain BEB33were analyzed, which was able to produce plant hormone IAA, but unable to dissolve phosphorus, to produce nitrogen fixation and ACC dehydrogenase, and the contents of IAA were tested to reach24.47mg/L in culture medium after7days.From the indoor spotted plants experiment, field plot experiment and field experiment, the strains BEB33against Fusarium on indoor potted plants efficacy was tested as73.51%, the field plot experiments shown that inoculating anti-vaccination antagonistic strains BEB33and banana wilt pathogen FOC4in order, the controlling effect was77.49%, the controlling efficiency was71.06%if in a contrary incubating order, and in field experiment, the effect is62.06%.The antagonistic activity product against FOC4could be extracted by BEB33fermentation broth after acid precipitation. The antagonistic activity of its fermentation product was insensitive to temperature and pH; Observed by microscope, the FOC4mycelium was expanded, the branch growth was restrained, and the conidium germination was restrained under the effect of this strain. When the concentration of crude extraction of active product went up to more than8mg/mL, the FOC4conidia failed to germinate. The tasting results revealed that BEB33could produce siderophore in large amount in CAS agar Plate,BEB33genome DNA was used as template, primers were designed by fat peptides synthesis related genes SrfAA, Bmy, ituC through homology cloning method to conduct PCR amplification, three target fragments were obtained. After comparing the cloning and sequencing result in NCBI, the gene homology of SrfAA amplified fragment had99%similarity with the surfactin synthetase A of Bacillus amyloliquefaciens IT-45(CP004065.1). The gene homology of Bmy amplified fragment had97%similarity with the bmy A, which synthesize bacillomycin D in Bacillus amyloliquefaciens FZB42(CP000560.1). The gene homology of ituC amplified fragment had99%similarity with ituC, which synthesize Iturin A in Bacillus amyloliquefaciens AS43.3(CP003838.1). It indicated that Gene of Surfactin, bacillomycin D and Iturin A may exist in BEB33strains, and might produce the three relative lipopeptide antibiotics.