马蜂肠道菌抑制反枝苋的活性筛选及菌株MF06的活性代谢产物

Inhibition of Amaranthus retroflexus by wasp gut fungal isolate Fusarium oxysporum MF06

摘要:

摘要:【目的】研究马蜂肠道真菌对反枝苋的抑制活性，为开发微生物源除草剂奠定基础。【方法】通过测试11种肠道真菌发酵液对反枝苋根生长的抑制效果筛选出活性菌株MF06。通过形态学观察和分子生物学鉴定确定MF06的分类地位。通过硅胶柱层析法、薄层层析法、葡聚糖凝胶柱层析法对乙酸乙酯粗提物进行分离、纯化，得到代谢产物1，研究代谢产物1对反枝苋根生长的抑制作用。利用核磁共振谱和质谱确定代谢产物1的化学结构。【结果】经形态学观察和ITS序列分析确定MF06菌株为尖孢镰刀菌(Fusarium oxysporum)。当供试质量浓度为100 μg/mL时，该菌株发酵液的乙酸乙酯提取物对反枝苋根生长的抑制率大于68%。从乙酸乙酯粗提物中分离得到代谢产物1，经过结构鉴定为镰刀菌酸与9，10-脱氢镰刀菌酸以1:1比例形成的混合物。活性测试表明代谢产物1对反枝苋根生长具有很强的抑制作用，抑制活性的IC50值为(0.51±0.18)μg/mL，与阳性对照药2，4-二氯苯氧乙酸的活性［IC50值为(0.30±0.14)μg/mL］相当。【结论】MF06菌株具有开发为微生物源除草剂的潜力。

Abstract:

Abstract:［Objective］ To study the inhibitory effect of wasp gut fungus against the radicle growth of Amaranthus retroflexus for the development of herbicides from microorganisms.［Methods］Eleven strains were isolated from wasp gut．Among them the fermentation broth of strain MF06 showed potent herbicidal activity against A．retroflexus．MF06 was identified by morphological observation and molecular biology identification．Fermentation product was isolated and purified by silica column chromatography，TLC and Sephadex LH-20 column chromatography．Metabolite 1 was obtained from fermentation product，and the inhibitory effect of metabolite 1 against the radicle growth of A．retroflexus was studied．The structure was determined by mass spectrum and nuclear magnetic resonance analyses.［Results］By the morphological observation and ITS sequence analysis，MF06 was identified as Fusarium oxysporum． The ethyl acetate extract of MF06 had strong activity against A．retroflexus with inhibition rate of more than 68% under the concentration of 100 μg/mL． It is better than other polarities crude extracts．Metabolite 1 was separated from ethyl acetate extract，and it was determined as a mixture of fusaric acid and 9，10-dehydrofusaric acid．The mixture is co-crystallizing in a 1:1 molar stoichiometry．It inhibited radical growth of A． retroflexus with IC50 value of (0.51±0.18)μg /mL，comparable to that of 2-(2，4-dichlorophenoxy) acetic acid (0.30±0.14 μg/mL) used as a positive control．［Conclusion］ Strain MF06 could be potentially developed as a microbial herbicide．