Microbial Processes and Interactions Laboratory, Terra Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liègegrid.4861.b, Gembloux, Belgium.
UMR Ecologie Microbienne, University of Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, Villeurbanne, France.
Microbiol Spectr. 2021 Dec 22;9(3):e0203821. doi: 10.1128/spectrum.02038-21. Epub 2021 Dec 8.
Some species, such as B. velezensis, are important members of the plant-associated microbiome, conferring protection against phytopathogens. However, our knowledge about multitrophic interactions determining the ecological fitness of these biocontrol bacteria in the competitive rhizosphere niche is still limited. Here, we investigated molecular mechanisms underlying interactions between and Pseudomonas as a soil-dwelling competitor. Upon their contact-independent confrontation, a multifaceted macroscopic outcome was observed and characterized by growth inhibition, white line formation in the interaction zone, and enhanced motility. We correlated these phenotypes with the production of bioactive secondary metabolites and identified specific lipopeptides as key compounds involved in the interference interaction and motile response. mobilizes its lipopeptide surfactin not only to enhance motility but also to act as a chemical trap to reduce the toxicity of lipopeptides formed by Pseudomonas. We demonstrated the relevance of these unsuspected roles of lipopeptides in the context of competitive tomato root colonization by the two bacterial genera. Plant-associated Bacillus velezensis and Pseudomonas spp. represent excellent model species as strong producers of bioactive metabolites involved in phytopathogen inhibition and the elicitation of plant immunity. However, the ecological role of these metabolites during microbial interspecies interactions and the way their expression may be modulated under naturally competitive soil conditions has been poorly investigated. Through this work, we report various phenotypic outcomes from the interactions between and 10 Pseudomonas strains used as competitors and correlate them with the production of specific metabolites called lipopeptides from both species. More precisely, overproduces surfactin to enhance motility, which also, by acting as a chemical trap, reduces the toxicity of other lipopeptides formed by Pseudomonas. Based on data from interspecies competition on plant roots, we assume this would allow to gain fitness and persistence in its natural rhizosphere niche. The discovery of new ecological functions for and Pseudomonas secondary metabolites is crucial to rationally design compatible consortia, more efficient than single-species inoculants, to promote plant health and growth by fighting economically important pathogens in sustainable agriculture.
一些物种，如 B. velezensis，是植物相关微生物组的重要成员，可抵御植物病原体。然而，我们对这些生防细菌在竞争根际生态位中决定其生态适应性的多营养级相互作用的了解仍然有限。在这里，我们研究了 与作为土壤居住竞争者的假单胞菌之间相互作用的分子机制。在它们非接触对抗中，观察到了多方面的宏观结果，并通过 生长抑制、相互作用区的白线形成和增强的运动性对其进行了特征描述。我们将这些表型与生物活性次生代谢物的产生相关联，并确定了特定的脂肽作为参与干扰相互作用和运动反应的关键化合物。 不仅动员其脂肽表面活性剂来增强运动性，而且还将其用作化学陷阱来降低假单胞菌形成的脂肽的毒性。我们证明了这些脂肽在两种细菌属对番茄根定殖的竞争情况下的这些意想不到的作用的相关性。 植物相关的芽孢杆菌 velezensis 和假单胞菌属代表了具有生物活性代谢物的优秀模型物种，这些代谢物参与抑制植物病原体和诱导植物免疫。然而，这些代谢物在种间微生物相互作用中的生态作用以及它们在自然竞争土壤条件下的表达方式如何被调节，仍未得到充分研究。通过这项工作，我们报告了 与作为竞争者的 10 株假单胞菌菌株之间相互作用的各种表型结果，并将其与来自两种物种的特定代谢物（称为脂肽）的产生相关联。更准确地说， 过度产生表面活性剂以增强运动性，同时通过充当化学陷阱，还降低了假单胞菌形成的其他脂肽的毒性。基于在植物根上的种间竞争数据，我们假设这将使 能够在其自然根际生态位中获得适应性和持久性。发现芽孢杆菌和假单胞菌次生代谢物的新生态功能对于合理设计相容的联合体至关重要，这些联合体比单一物种接种剂更有效，通过在可持续农业中对抗经济上重要的病原体来促进植物健康和生长。
