Drosophila melanogaster gut microbes play important roles in host nutritional physiology. However, these associations are often indirect and studies typically are in the context of specialized nutritional conditions, making it difficult to discern how microbiome-mediated impacts translate to physiologically relevant conditions, in the laboratory or nature. Here, we show that on three artificial diets and a natural diet of grapes, D. melanogaster gut bacteria alter protein, carbohydrates, and moisture of the food substrate. In depth analysis on one diet revealed bacteria also increase tryptophan levels. We investigate how nutrient changes impact life history and find that, while alterations to dietary protein and carbohydrates are arguably the most significant consequence of bacterial association, other factors, such as micronutrients, likely contribute to life history traits in a diet-dependent manner. Our work demonstrates that while some bacterial impacts on nutrition occur across experimental diets, others are dictated by unique dietary environments.

中文翻译：

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肠道细菌介导果蝇饮食中的养分供应

果蝇腹肠道微生物在宿主营养生理中起重要作用。但是，这些关联通常是间接的，研究通常是在特殊的营养条件下进行的，因此很难辨别微生物组介导的影响如何转化为实验室或自然环境中的生理相关条件。在这里，我们证明了在三种人工饮食和天然饮食的葡萄中，D。melanogaster肠道细菌会改变食物基质中的蛋白质，碳水化合物和水分。对一种饮食进行深入分析后发现，细菌也会增加色氨酸水平。我们研究了养分变化如何影响生活史，发现尽管饮食中蛋白质和碳水化合物的改变可能是细菌缔合的最重要结果，但其他因素（例如微量营养素）也可能以饮食依赖的方式促成生活史特征。我们的工作表明，虽然实验饮食中某些细菌对营养的影响会发生，但其他细菌则是由独特的饮食环境决定的。