Diet selection is a fundamental aspect of animal behavior with numerous ecological and evolutionary implications. While the underlying mechanisms are complex, the availability of essential dietary nutrients can strongly influence diet selection behavior. The gut microbiome has been shown to metabolize many of these same nutrients, leading to the untested hypothesis that intestinal microbiota may influence diet selection. Here we show that germ-free mice colonized by gut microbiota from three rodent species with distinct foraging strategies differentially selected diets that varied in macronutrient composition. Specifically, we found that herbivore-conventionalized mice voluntarily selected a higher protein:carbohydrate ratio diet, while omnivore- and carnivore-conventionalized mice selected a lower P:C ratio diet. In support of the long-standing hypothesis that tryptophan – the essential amino acid precursor of serotonin – serves as a peripheral signal regulating diet selection, bacterial genes involved in tryptophan metabolism and plasma tryptophan availability prior to the selection trial were significantly correlated with subsequent voluntary carbohydrate intake. Finally, herbivore-conventionalized mice exhibited larger intestinal compartments associated with microbial fermentation, broadly reflecting the intestinal morphology of their donor species. Together, these results demonstrate that gut microbiome can influence host diet selection behavior, perhaps by mediating the availability of essential amino acids, thereby revealing a novel mechanism by which the gut microbiota can influence host foraging behavior.

中文翻译：

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肠道微生物组影响宿主的饮食选择行为

饮食选择是动物行为的一个基本方面，具有许多生态和进化意义。虽然潜在的机制很复杂，但必需饮食营养素的可用性会强烈影响饮食选择行为。肠道微生物组已被证明可以代谢许多相同的营养物质，这导致了未经检验的假设，即肠道微生物群可能会影响饮食选择。在这里，我们展示了由三种啮齿动物的肠道微生物群定殖的无菌小鼠，它们具有不同的觅食策略，不同地选择了宏量营养素组成不同的饮食。具体来说，我们发现食草动物常规小鼠自愿选择较高蛋白质：碳水化合物比例的饮食，而杂食动物和食肉动物常规小鼠选择较低的 P：C 比例饮食。为了支持色氨酸（血清素的必需氨基酸前体）作为调节饮食选择的外周信号这一长期存在的假设，在选择试验之前参与色氨酸代谢和血浆色氨酸可用性的细菌基因与随后的自愿碳水化合物显着相关录取。最后，食草动物的常规化小鼠表现出与微生物发酵相关的更大的肠道隔室，广泛反映了其供体物种的肠道形态。总之，这些结果表明肠道微生物组可以影响宿主的饮食选择行为，可能是通过调节必需氨基酸的可用性，从而揭示肠道微生物群可以影响宿主觅食行为的新机制。