Co-culturing the bacterium Streptomyces rapamycinicus and the ascomycete Aspergillus nidulans has previously been shown to trigger the production of orsellinic acid (ORS) and its derivates in the fungal cells. Based on these studies it was assumed that direct physical contact is a prerequisite for the metabolic reaction that involves a fungal amino acid starvation response and activating chromatin modifications at the biosynthetic gene cluster (BGC). Here we show that not physical contact, but a guanidine containing macrolide, named polaramycin B, triggers the response. The substance is produced constitutively by the bacterium and above a certain concentration, provokes the production of ORS. In addition, several other secondary metabolites were induced by polaramycin B. Our genome-wide transcriptome analysis showed that polaramycin B treatment causes downregulation of fungal genes necessary for membrane stability, general metabolism and growth. A compensatory genetic response can be observed in the fungus that included upregulation of BGCs and genes necessary for ribosome biogenesis, translation and membrane stability. Our work discovered a novel chemical communication, in which the antifungal bacterial metabolite polaramycin B leads to the production of antibacterial defence chemicals and to the upregulation of genes necessary to compensate for the cellular damage caused by polaramycin B.

中文翻译：

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Polaramycin B，而不是物理相互作用，是在链霉菌 - 曲霉菌相互作用中重新连接真菌代谢的信号

共培养雷帕霉素链霉菌和子囊菌构巢曲霉先前已被证明可以触发真菌细胞中奥赛林酸 (ORS) 及其衍生物的产生。基于这些研究，假设直接物理接触是代谢反应的先决条件，该反应涉及真菌氨基酸饥饿反应和激活生物合成基因簇 (BGC) 的染色质修饰。在这里，我们表明不是身体接触，而是含有大环内酯的胍（名为 polaramycin B）触发反应。该物质由细菌组成型产生，并且在一定浓度以上，会引起 ORS 的产生。此外，极霉素 B 还诱导了其他几种次级代谢产物。我们的全基因组转录组分析表明，极霉素 B 处理会导致膜稳定性所必需的真菌基因下调，一般新陈代谢和生长。在真菌中可以观察到补偿性遗传反应，包括上调 BGC 和核糖体生物发生、翻译和膜稳定性所必需的基因。我们的工作发现了一种新的化学通讯，其中抗真菌细菌代谢物 polaramycin B 导致抗菌防御化学物质的产生以及补偿 polaramycin B 引起的细胞损伤所必需的基因的上调。