Much is known about molecular mechanisms by which animals detect pathogenic microbes, but how animals sense beneficial microbes remains poorly understood. The roundworm Caenorhabditis elegans is a microbivore that must distinguish nutritive microbes from pathogens. We characterized a neural circuit used by C. elegans to rapidly discriminate between nutritive bacteria and pathogens. Distinct sensory neuron populations responded to chemical cues from nutritive Escherichia coli and pathogenic Enterococcus faecalis, and these neural signals are decoded by downstream AIB interneurons. The polyamine metabolites cadaverine, putrescine, and spermidine produced by E. coli activate this neural circuit and elicit positive chemotaxis. Our study shows how polyamine odorants can be sensed by animals as proxies for microbe identity and suggests that, hence, polyamines might have widespread roles brokering host-microbe interactions.

中文翻译：

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多胺代谢物的化学感应检测引导秀丽隐杆线虫寻找营养微生物

人们对动物检测病原微生物的分子机制了解很多，但对动物如何感知有益微生物仍知之甚少。线虫是一种食微生物动物，必须区分营养微生物和病原体。我们描述了秀丽隐杆线虫用来快速区分营养细菌和病原体的神经回路。不同的感觉神经元群体对来自营养性大肠杆菌和致病性粪肠球菌的化学信号做出反应，这些神经信号由下游 AIB 中间神经元解码。大肠杆菌产生的多胺代谢物尸胺、腐胺和亚精胺激活该神经回路并引发正趋化性。我们的研究表明，多胺气味剂如何被动物感知为微生物身份的代表，并表明，因此，多胺可能在调节宿主与微生物的相互作用中发挥广泛的作用。