虫草素产量不同的蛹虫草菌株代谢组差异

为探究虫草素高产和低产的两株蛹虫草菌代谢差异及其与虫草素代谢的关联性,本研究采用UPLC-QTOF-MS广泛靶向代谢组学技术和多元统计分析方法,结合相同蛹虫草菌不同发酵时间的菌丝体差异代谢物相对含量的变化情况,比较了两株蛹虫草菌相同发酵时间的菌丝体代谢差异。结果表明：蛹虫草CICC 14014菌株发酵第20和10天的菌粉（H20和H10）及其发酵液的虫草素含量都显著高于蛹虫草CGMCC 3.4655菌株（其菌粉为L20和L10）（P<0.01）。主成分模型显示H10、L10、H20和L20间分散明显;通过正交偏最小二乘法分析,以t检验P<0.05并且VIP>1为标准,从H10 vs L10和H20 vs L20分别识别出190和158种差异代谢物,其中具有生物活性的亚精胺为首次在蛹虫草菌中被检出;以P<0.01为标准,从H10 vs L10、H20 vs L20中筛选出2条显著富集的通路,分别为烟酸-烟酰胺和精氨酸-脯氨酸代谢通路。对H10 vs L10和H20 vs L20进行代谢调控网络分析,获得7条显著互作的通路,相同的互作通路为碱基切除修复。代谢网络分析结果表明抑制三羧酸循环、核黄素代谢、赖氨酸降解、鞘脂类代谢通路以及促进碱基切除修复、β-丙氨酸代谢、精氨酸-脯氨酸代谢、脂质代谢、嘌呤代谢通路有利于虫草素的生成;虫草素高产蛹虫草菌甘油三酯代谢和合成腺苷的能力高于虫草素低产蛹虫草菌;在嘌呤代谢途径中,腺嘌呤通过黄嘌呤代谢反馈促进虫草素的生物合成。本研究为蛹虫草菌生物活性成分的挖掘提供理论基础,为深入解析蛹虫草菌虫草素的代谢机制提供参考。

Differential metabolomic analyses of Cordyceps militaris strains with different capacity for cordycepin production

UPLC-QTOF-MS widely-targeted metabolomics combined with multivariate statistical methods was applied to compare differential metabolism between mycelium of two strains of Cordyceps militaris with different cordycepin production capacity under the same culture time, based on relative content variation of differential metabolites at different fermentation time. The results showed that cordycepin content in mycelial powder (H20 and H10 individually obtained on day 20 and day 10 of fermentation) and liquid broth of the strain CICC 14014 were significantly higher than that in mycelial powder (L20 and L10) and liquid broth of the strain CGMCC 3.4655 (P<0.01). Results of PCA showed obvious difference among four perimental groups (H20, H10, L20, and L10). The differential metabolites selected in condition of P<0.05 and VIP>1 using OPLS-DA analysis were 190 (H10 vs L10) and 158 (H20 vs L20). Bioactive spermidine was first found in four samples. Analysis of pathway enrichment indicated two significantly enriched pathways (P<0.01). Differential metabolites of H10 vs L10 and H20 vs L20 were enriched in the pathways of nicotinate-nicotinamid and arginine-proline metabolism, respectively. According to the analytic results of metabolic regulatory network of H10 vs L10 and H20 vs L20, seven significantly interactive pathways were selected. The pathway of base excision repair was the same interactive pathway. It is assumed that the inhibition of TCA cycle, riboflavin metabolism, lysine degradation and sphingolipid metabolism and the acceleration of base excision repair, β-alanine metabolism, arginine-proline metabolism, lipid metabolism and purine metabolism are considered to promote cordycepin production. The efficiency of triglyceride metabolism and adenosine synthesis in strain CICC 14014 with high cordycepin-producing capacity is higher than that in strain CGMCC 3.4655 with low cordycepin content. Adenine accelerates cordycepin biosynthesis through xanthine metabolism involved in purine metabolic pathway. The conclusion of our research provide a basis for detection of new bioactive compounds and for uncovery of cordycepin metabolism in strain of C. militaris.