黄蜻幼虫肠道分离菌QTYC38活性代谢产物的分离和鉴定

Isolation and identification of bioactive secondary metabolites produced by strain QTYC38,a fungus isolated from the gut of Pantala flavescens larvae

【目的】黄蜻幼虫肠道分离菌QTYC38菌株的鉴定及抗菌除草活性代谢物的研究。【方法】通过形态学观察及分子生物学ITS序列分析,对菌株QTYC38进行鉴定。利用生长速率法和琼脂扩散法测定菌株粗提物及其单体化合物的抗菌活性,结合培养皿生物分析法测定菌株粗提物及其单体化合物的除草活性。同时运用多种色谱方法分离发酵产物中的活性成分,并根据质谱和核磁共振谱数据确定其结构。【结果】菌株QTYC38被鉴定为浅黄新萨托菌Neosartorya aureola,在供试浓度为100μg/mL时,其粗提物对稗草和反枝苋的生长抑制活性较好,抑制率均大于65%;当供试浓度为30μg/滤纸片时,其对金黄色葡萄球菌(Staphyloccocus aureus)具有较好的抑菌活性,抑菌圈直径为22.7 mm,与阳性对照药(硫酸庆大霉素23.2 mm)活性相当。从该菌固体发酵产物中分离纯化得到4个单体化合物:helvolic acid(1),aromatic lactones(2),questin(3)和erogosterol(4)。其中,化合物1对枯草芽孢杆菌(Bacillus subtilis)和金黄色葡萄球菌(S.aureus)均具有较好的生长抑制活性,最低抑菌浓度分别为3.1和1.5μg/mL;当供试浓度为100μg/mL时,化合物3和化合物4分别对杨树溃疡病菌(Dothiorella gregaria)和小麦赤霉病菌(Fusarium graminearum)具有较好的抑制效果,抑制率分别为52.4%和72.3%。【结论】菌株QTYC38具有开发为微生物源除草剂和新型杀菌剂的潜能。

[Objective] To identify strain QTYC38, a fungus isolated from the gut of Pantala flavescens larvae, and study its phytotoxic and antimicrobial metabolites. [Methods] QTYC38 was identified by morphological observation and molecular biological analysis. Growth rate method and agar disc diffusion assays were used to test the antimicrobial activities. Petri-dish bioassay was used to test the phytotoxic activity. Bioactive components were isolated via chromatographic methods, and the structures were determined by mass spectrum and nuclear magnetic resonance analyses. [Results] QTYC38 was identified as Neosartorya aureola. Ethyl acetate extract of QTYC38 inhibited radical growth of Echinochloa crusgalli and Amaranthus retroflexus with the inhibition rates above 65% with the concentration of 100 μg/mL, The extract also inhibited Staphyloccocus aureus with the mean halo diameter of 22.7 mm with the concentration of 30 μg/filter. Four compounds were purified from the solid fermentation product： helvolic acid, aromatic lactones, questin and erogosterol. Helvolic acid inhibited the growth of Bacillus subtilis and S. aureus with the MIC values of 3.1 and 1.5 μg/mL, respectively. Questin and erogosterol inhibited Dothiorella gregaria and Fusarium graminearum at the concentration of 100 μg/mL, with the inhibition rates of 52.4% and 71.3%, respectively. [Conclusion] Strain QTYC38 could be potentially developed as a microbial herbicide and new antimicrobial agent.