小麦赤霉病生防菌的筛选及其活性物的初步研究

A Preliminary Study on Screening of Biocontrol Bacteria Against Wheat Head Blight and their Bioactive Compounds

本研究以课题组前期筛选获得的8株具有生防活性潜力的细菌为基础,从中筛选具有防治小麦赤霉病的活性菌株,并初步探究其生防活性基础。通过平板对峙法初步筛选,结果发现,2株解淀粉芽孢杆菌(Bacillus amyloliquefaciens)DEB-2与D_(1)具有较高的抑菌活性,抑菌率分别为51.32%和49.48%,DEB-2发酵物的抑菌活性高于D_(1)。菌株遗传稳定性和菌株发酵液对紫外照射敏感性检测发现,DEB-2和D_(1)都具较高的稳定性,且二者之间均无明显差异。在pH值和温度稳定性方面,DEB-2的稳定性显著高于D_(1),DEB-2不受pH值影响,D_(1)随pH值升高而活性降低;在121℃时,DEB-2发酵液抑菌率仍保持在62.35%,D_(1)下降至15.74%。生测结果表明,DEB-2的防治效果明显高于同类市售枯草芽孢杆菌。由此,以DEB-2作为小麦赤霉病生物防治的候选菌株。为进一步探究DEB-2活性的物质基础,利用GC-MS分析活性乙酸乙酯层,发现一个环-(L-苯丙氨酸-L-脯氨酸)化合物,其已被报道具有较强的拮抗小麦赤霉病菌的作用。由此推测,DEB-2对小麦赤霉病菌具有较高的拮抗作用可能与其产生的环-(L-苯丙氨酸-L-脯氨酸)相关。

Based on the eight bacteria strains with potential bio-control activities obtained by our research group in the early stage,this study screens the bioactive strains against F.graminearum,and initially explores the substantial basis of their bio-control activities.Preliminary screening of the strains via the plate confrontation method showed that two strains of Bacillus amyloliquefaciens DEB-2 and D_(1) had high antifungal activities with the rates of 51.32%and 49.48%respectively.The fermentation broth of DEB-2 had significantly greater antifungal activities than that of D_(1)(P<0.01).The genetic stabilities of the strains and the sensitivities of the fermentation broth of the strains to ultraviolet radiation revealed that both DEB-2 and D_(1) had high stabilities with no significant difference.However,in terms of pH and temperature stabilities,the stabilities of DEB-2 were significantly higher than that of D_(1)(P<0.01).DEB-2 was not affected by pH change,while D_(1) decreased in activity with pH increasing.At 121℃,the antifungal activities of DEB-2 fermentation broth remained 62.35%,while D_(1) dropped to 15.74%.The bioassay results also showed that the control effects of DEB-2 was significantly higher(P<0.01)than commercial bio-control agent Bacillus subtilis strain.Therefore,DEB-2 was selected as a candidate strain for biological control of wheat head blight.In order to explore the substantial basis of DEB-2 bioactivity,a cyclic-(L-phenylalanine-L-proline)was found via GC-MS analysis of the bioactive ethyl acetate layer,which was reported to have a relatively strong antifungal effect on wheat head blight.It can be speculated that DEB-2 had a antifungal effect against F.graminearum,which may be related to the production of cyclo-(L-phenylalanine-L-proline).