Max Planck Institute for Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, Tuebingen, 72076, Germany.
Max Planck Institute for Biology, Department for Integrative Evolutionary Biology, Max-Planck-Ring 9, Tuebingen, 72076, Germany.
Curr Biol. 2022 May 9;32(9):2037-2050.e4. doi: 10.1016/j.cub.2022.03.056. Epub 2022 Apr 8.
Animals are associated with a diverse bacterial community that impacts host physiology. It is well known that nutrients and enzymes synthesized by bacteria largely expand host metabolic capacity. Bacteria also impact a wide range of animal physiology that solely depends on host genetics through direct interaction. However, studying the synergistic effects of the bacterial community remains challenging due to its complexity. The omnivorous nematode Pristionchus pacificus has limited digestive efficiency on bacteria. Therefore, we established a bacterial collection that represents the natural gut microbiota that are resistant to digestion. Using this collection, we show that the bacterium Lysinibacillus xylanilyticus by itself provides limited nutritional value, but in combination with Escherichia coli, it significantly promotes life-history traits of P. pacificus by regulating the neuroendocrine peptide in sensory neurons. This gut-to-brain communication depends on undigested L. xylanilyticus providing Pristionchus nematodes a specific fitness advantage to compete with nematodes that rupture bacteria efficiently. Using RNA-seq and CRISPR-induced mutants, we show that 1-h exposure to L. xylanilyticus is sufficient to stimulate the expression of daf-7-type TGF-β signaling ligands, which induce a global transcriptome change. In addition, several effects of L. xylanilyticus depend on TGF-β signaling, including olfaction, body size regulation, and a switch of energy allocation from lipid storage to reproduction. Our results reveal the beneficial effects of a gut bacterium to modify life-history traits and maximize nematode survival in natural habitats.
动物与影响宿主生理的多样化细菌群落有关。众所周知，细菌合成的营养物质和酶在很大程度上扩大了宿主的代谢能力。细菌还通过直接相互作用影响广泛的动物生理，而这些生理仅取决于宿主遗传。然而，由于其复杂性，研究细菌群落的协同效应仍然具有挑战性。杂食性线虫 Pristionchus pacificus 对细菌的消化效率有限。因此，我们建立了一个细菌集合，代表了天然肠道微生物群，这些微生物群对消化具有抗性。使用这个集合，我们表明，单独的细菌 Lysinibacillus xylanilyticus 本身提供的营养价值有限，但与 Escherichia coli 结合使用时，它通过调节感觉神经元中的神经内分泌肽，显著促进了 P. pacificus 的生活史特征。这种肠道到大脑的通讯依赖于未消化的 L. xylanilyticus 为秀丽隐杆线虫提供特定的适应优势，以与有效破裂细菌的线虫竞争。使用 RNA-seq 和 CRISPR 诱导的突变体，我们表明，1 小时暴露于 L. xylanilyticus 足以刺激 daf-7 型 TGF-β 信号配体的表达，从而诱导全转录组变化。此外，L. xylanilyticus 的几种作用依赖于 TGF-β 信号，包括嗅觉、体型调节以及从脂质储存到繁殖的能量分配的转变。我们的研究结果揭示了肠道细菌对修饰生活史特征和最大限度地提高自然栖息地中线虫生存能力的有益影响。
