Strain 246-1,which was isolated from the soil beside of Qinghai Lake,had a high antagonistic activity against F.oxysporum f.sp.cucumerinum.It was identified as Paenibacillus polymyxa based on the 16S rDNA sequence.The extraction and detection methods of fusaricidins were screened and,the fermented liquid acid was proved to be an important step of fusaricidins extraction and purification.The acetonitrile/water/TFA detection system was used for detecting fusaricidins by HPLC.We selected the most suitable medium for P.polymyxa 246-1 to produce fusaricidins by using the inhibition zones experiment and designed according to single factor experiment.The optimal medium for strain 246-1 consisted of 17.5 g · L-1 soluble starch,4 g · L-1 yeast extract powder,25 g · L-1 peptone,1.25 g · L-1NaCl,0.5 g · L-1 Na2 HPO4,CaCl2 1g · L-1,15 g · L-1 sucrose.And the fermentation time is 48 h,pH 7.0 and 30 ℃.Further analysis was conducted including the growth of cucumber seedlings influenced by strain 246-1,rhizosphere colonization ability of 246-1 and its control effect on cucumber wilt disease.The results of pot experiment showed that,strain 246-1 had significant biocontrol effects against fusarium wilt disease in cucumber seedlings resulted from the F.oxysporum f.sp.cucumerinum.It also.can promote the growth of cucumber seedlings and displayed strong colonization ability in the rhizosphere of cucumber seedlings.%分离自青海湖周边土壤的菌株246-1平板对峙实验显示了对黄瓜枯萎病菌(Fusarium oxysporum f.sp.cucumerinum)的抑制作用.通过16S rDNA鉴定其为多黏类芽孢杆菌(Paenibacillus polymyxa).实验通过筛选fusaricidins提取纯化和检测方法,确定发酵液酸化是fusaricidins提取纯化的一个重要步骤;同时确定乙腈/水/TFA检测体系为fusaricidins HPLC检测流动相.采用抑菌圈实验筛选出最适合多黏类芽孢杆菌246-1产fusaricidins的培养基,用单因素实验方法对其培养条件进行优化.结果表明,246-1菌株的培养基配方为可溶性淀粉17.5 g/L,酵母浸出粉4g/L,蛋白胨25 g/L,NaC1 1.25 g/L,Na2HPO40.5 g/L,CaCl21g/L,蔗糖15 g/L,最佳培养时间48 h,初始pH 7.0,培养温度30℃.进一步分析了多黏类芽孢杆菌246-1对黄瓜幼苗的促生作用,在黄瓜幼苗根际的定殖能力和对黄瓜枯萎病的防效作用.盆栽试验结果表明,菌株246-1的发酵上清液对黄瓜枯萎病菌表现出很强的抑制作用,同时该菌株在黄瓜幼苗根际具有很好的定殖能力,表现了对黄瓜幼苗的显著促生效果.
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