Ansamitocin P-3 (AP-3), a 19-membered polyketide macrocyclic lactam, has potent antitumor activity. Our previous study showed that a relatively low organic nitrogen concentration in culture medium could significantly improve AP-3 production of Actinosynnema pretiosum. In the present study, we aimed to reveal the possible reasons for this improvement through metabolomic and gene transcriptional analytical methods. At the same time, a metabolic pathway profile based on metabolome data and pathway correlation information was performed to obtain a systematic view of the metabolic network modulations of A. pretiosum. Orthogonal partial least squares discriminant analysis showed that nine and eleven key metabolites directly associated with AP-3 production at growth phase and ansamitocin production phase, respectively. In-depth pathway analysis results highlighted that low organic nitrogen availability had significant impacts on central carbon metabolism and amino acid metabolic pathways of A. pretiosum and these metabolic responses were found to be beneficial to precursor supply and ansamitocin biosynthesis. Furthermore, real-time PCR results showed that the transcription of genes involved in precursor and ansamitocin biosynthetic pathways were remarkably upregulated under low organic nitrogen condition thus directing increased carbon flux toward ansamitocin biosynthesis. More importantly, the metabolic pathway analysis demonstrated a competitive relationship between fatty acid and AP-3 biosynthesis could significantly affect the accumulation of AP-3. Our findings provided new knowledge on the organic nitrogen metabolism and ansamitocin biosynthetic precursor in A. pretiosum and identified several important rate-limiting steps involved in ansamitocin biosynthesis thus providing a theoretical basis of further improvement in AP-3 production.

中文翻译：

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代谢组学变化和途径分析表明，嗜酸放线放线菌中安索霉素P-3的产量增加，而培养基中的有机氮利用率较低。

Ansamitocin P-3（AP-3）是一种19元的聚酮化合物大环内酰胺，具有强大的抗肿瘤活性。我们以前的研究表明，培养基中相对较低的有机氮浓度可以显着提高猕猴桃放线菌AP-3的产量。在本研究中，我们旨在通过代谢组学和基因转录分析方法揭示这种改善的可能原因。同时，进行了基于代谢组学数据和途径相关信息的代谢途径概况分析，以获取有关Pre.iosus的代谢网络调节的系统视图。正交偏最小二乘判别分析表明，与AP-3生产直接相关的9个和11个关键代谢物分别在生长期和安托霉素生产阶段。深入的途径分析结果表明，低有机氮的利用率对pre曲霉的中央碳代谢和氨基酸代谢途径有显着影响，并且这些代谢反应被发现有利于前体供应和安托霉素的生物合成。此外，实时PCR结果表明，在低有机氮条件下，涉及前体和安托霉素生物合成途径的基因的转录显着上调，从而将增加的碳通量导向安托霉素生物合成。更重要的是，代谢途径分析表明脂肪酸与AP-3生物合成之间的竞争关系可能显着影响AP-3的积累。