Microbes living in the guts of fruit flies appear to influence the flies' food choice—and promote egg production, even under a nutrient-poor diet.

生活在果蝇肠道中的微生物似乎会影响苍蝇的食物选择——而且还能促进产卵，即使在营养不均衡的情况下。

撰文/播音：克里斯托弗·因塔利亚塔(Christopher Intagliata)

翻译：路识宇

审校：杨枭

Just like humans, fruit flies have to eat a balanced diet. 

和人类一样，果蝇也需要均衡的饮食。

"They need sugar to survive, they need amino acids to make eggs, to have stem cells proliferate. They need salt, they need vitamins." 

“它们需要糖来维持生命，需要氨基酸来产卵，还有为了让干细胞增殖，它们也需要盐和维生素。”

Carlos Ribeiro, a neuroscientist at the Champalimaud Center in Portugal. Yeast, he says, is a crucial component of the fly diet. "I always say, yeast is the steak of the fly."

卡洛斯·里贝罗（Carlos Ribeiro）是葡萄牙Champalimaud中心(位于葡萄阿里斯本，是葡萄牙第一个大型研究中心)的神经科学家。他说，酵母是苍蝇饮食的重要组成部分。 “我一直说，酵母相当于苍蝇的牛排。”

Take yeast away, and the flies crave it—gotta make those eggs. Ribeiro and his team found they could also elicit that yearning for yeast simply by removing a few key amino acids from the flies' diet—but only in those flies that had their gut microbiome wiped out.  

把食物中的酵母菌移除后，苍蝇就会特别渴求它，因为苍蝇依靠酵母菌来产卵。里贝罗 和他的团队发现仅仅通过把几个关键的氨基酸从苍蝇的饮食中去除就可以诱发苍蝇对酵母菌的渴求，但仅限于那些肠道微生物被去除了的苍蝇。

Here’s the twist: when Ribeiro and his colleagues restored the standard fly gut microbiome, amino-acid-deprived flies did not seek out yeast to compensate. That might seem like the gut microbes are actually working against the flies' best interest—blocking their instincts to seek out missing nutrients. 

但实验的进展出现了转变: 当里贝罗和他的同事重新在苍蝇的肠道中放入了肠道微生物之后，饮食中没有关键氨基酸的苍蝇不再通过寻找酵母菌来补偿饮食中的缺失了。这看上去像是肠道微生物在干扰苍蝇寻找它最需要的物质，也就是说，肠道微生物在阻止苍蝇找寻缺失营养的本能。

But what actually happened, Ribeiro says, is that flies with the gut microbes maintained good egg production despite their nutritional deficiency. Suggesting that somehow, microbes help the flies adapt to nutrient-poor conditions. 

里贝罗说，但是实际上，尽管营养不足，肠胃中有肠道微生物的苍蝇仍可以保证产卵的质量和数量。这就意味着肠道微生物能够帮助苍蝇适应营养不良的生存条件。

"So somehow the microbes reprogram the metabolism of the fly to now cope better with an absence of amino acids in the diet. And that might also lead then to the fly not having to produce a strong craving for amino acids." The study is in the journal PLoS Biology. [Ricardo Leitão-Gonçalves et al., Commensal bacteria and essential amino acids control food choice behavior and reproduction]

“所以说微生物以某种方法重新调整了苍蝇的新陈代谢从而使它们可以更好地应对饮食中缺乏氨基酸的情况，这也可能导致苍蝇不再产生对氨基酸的强烈渴望。”该研究刊登在“PLoS Biology”杂志上。 [RicardoLeitão-Gonçalves et al.，共生细菌和必需氨基酸控制食物选择行为和繁殖](注: 作者为: Ricardo Leitão-Gonçalves 等人，该文章的名字为: Commensal bacteria and essential amino acids control food choice behavior and reproduction)

Of course, flies are not humans. But still, Ribeiro says, "I think there is now more and more compelling evidence that the microbes in the gut, also of humans, affect behavior, mood and stress, and maybe even, people propose, some diseases. But how microbes do so and why they would do so is completely unclear." 

当然，苍蝇和人类不同。但是，里贝罗表示，“我认为现在越来越有说服力的证据表明，肠道中的微生物，人类肠道中的微生物也是，会影响行为、心情和压力，有的人提出这甚至会影响病情。但微生物如何以及为什么这样做我们还不清楚。”

Still: next time you're staring at a menu, undecided on what to order…you might try just going with your gut.

那么当你下一次盯着菜单不知道要点什么的时候……尝试点些适合肠胃的食物吧。

—Christopher Intagliata