Fungal chemodiversity is well known in part due to the production of diverse analogous compounds by a single biosynthetic gene cluster (BGC). Usually, similar or the same metabolites are produced by closely related fungal species under a given condition, the foundation of fungal chemotaxonomy. Here, we report a rare case of the production of the cyclodepsipeptide beauveriolides (BVDs) in three insect-pathogenic fungi. We found that the more closely related fungi Beauveria bassiana and Beauveria brongniartii produced structurally distinct analogs of BVDs, whereas the less-close relatives B. brongniartii and Cordyceps militaris biosynthesized structurally similar congeners under the same growth condition. It was verified that a conserved BGC containing four genes is responsible for BVD biosynthesis in three fungi, including a polyketide synthase (PKS) for the production of 3-hydroxy fatty acids (FAs) with chain length variations. In contrast to BVD production patterns, phylogenetic analysis of the BGC enzymes or enzyme domains largely resulted in the congruence relationship with fungal speciation. Feeding assays demonstrated that an FA with a chain length of eight carbon atoms was preferentially utilized, whereas an FA with a chain longer than 10 carbon atoms could not be used as a substrate for BVD biosynthesis. Insect survival assays suggested that the contribution of BVDs to fungal virulence might be associated with the susceptibility of insect species. The results of this study enrich the knowledge of fungal secondary metabolic diversity that can question the reliability of fungal chemotaxonomy.

中文翻译：

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在密切相关的真菌中生产不同的 Beauveriolide 类似物：真菌化学多样性的一个罕见案例。

真菌化学多样性众所周知，部分原因是单个生物合成基因簇 (BGC) 可产生多种类似化合物。通常，相似或相同的代谢物是在给定条件下由密切相关的真菌物种产生的，这是真菌化学分类学的基础。在这里，我们报告了在三种昆虫病原真菌中产生环缩肽白僵菌 (BVD) 的罕见案例。我们发现，更密切相关的真菌白僵菌和布氏白僵菌产生结构上不同的 BVD 类似物，而不太近亲的B. brongniartii和蛹虫草在相同的生长条件下生物合成结构相似的同源物。经证实，包含四个基因的保守 BGC 负责三种真菌中的 BVD 生物合成，包括用于生产具有链长变化的 3-羟基脂肪酸 (FA) 的聚酮合酶 (PKS)。与 BVD 生产模式相反，BGC 酶或酶域的系统发育分析在很大程度上导致了与真菌物种形成的一致性关系。饲喂试验表明，优先使用链长为 8 个碳原子的 FA，而链长超过 10 个碳原子的 FA 不能用作 BVD 生物合成的底物。昆虫生存分析表明，BVD 对真菌毒力的贡献可能与昆虫物种的易感性有关。