Microbial interactions impact the functioning of microbial communities. However, microbial interactions within host-associated communities remains poorly understood. Here, we report that the beneficiary rhizobacterium Niallia sp. RD1 requires the helper Pseudomonas putida H3 for bacterial growth and beneficial interactions with the plant host. In the absence of the helper H3 strain, the Niallia sp. RD1 strain exhibited weak respiration and elongated cell morphology without forming bacterial colonies. A transposon mutant of H3 in a gene encoding succinate-semialdehyde dehydrogenase displayed much attenuated support of RD1 colony formation. Through subsequent addition of succinate to the media, we found that succinate serves as a public good that supports RD1 growth. Comparative genome analysis highlighted that RD1 lacked the gene for sufficient succinate, suggesting its evolution as a beneficiary of succinate biosynthesis. The syntrophic interaction between RD1 and H3 efficiently protected tomato plants from bacterial wilt and promoted the tomato growth. The addition of succinate to the medium restored complex II-dependent respiration in RD1 and facilitated the cultivation of various bacterial isolates from the rhizosphere. Taken together, we delineate energy auxotrophic beneficiaries ubiquitous in the microbial community, and these beneficiaries could benefit host plants with the aid of helpers in the rhizosphere.

中文翻译：

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辅助者和受益者之间的根际细菌互养促进番茄植株健康


微生物相互作用影响微生物群落的功能。然而，宿主相关群落内的微生物相互作用仍然知之甚少。在这里，我们报告受益根际细菌 Niallia sp。 RD1 需要辅助恶臭假单胞菌 H3 来促进细菌生长以及与植物宿主的有益相互作用。在没有辅助 H3 菌株的情况下，Niallia sp。 RD1菌株表现出弱呼吸和拉长的细胞形态，但未形成菌落。编码琥珀酸半醛脱氢酶的基因中的 H3 转座子突变体显示出对 RD1 集落形成的支持大大减弱。通过随后向培养基中添加琥珀酸，我们发现琥珀酸作为支持 RD1 生长的公共产品。比较基因组分析强调，RD1 缺乏足够琥珀酸的基因，表明其进化为琥珀酸生物合成的受益者。 RD1和H3之间的互养相互作用有效地保护番茄植株免受青枯病并促进番茄生长。向培养基中添加琥珀酸盐恢复了 RD1 中复合物 II 依赖性呼吸，并促进了根际各种细菌分离株的培养。综上所述，我们描绘了微生物群落中普遍存在的能量营养缺陷型受益者，这些受益者可以在根际帮助者的帮助下使宿主植物受益。