Molecular requirements of Bacillus subtilis root colonization

在土壤中，植物的根与大量的细菌一起生活。它们中的一些为植物提供有益的活动，以交换根分泌的营养。这些细菌可以通过调节其新陈代谢和对抗病原体来显著促进植物生长和健康。有益微生物开始在全球范围内用作生物肥料和生物农药，并构成化学肥料和农药的一种非常有趣和可持续的替代品。虽然细菌肥料很有前途，但仍有很大的改进空间。然而，目前缺乏关于这些微生物如何接近和定殖根部的基础知识，这大大减缓了生物肥料使用和配方的改进。我的研究计划是建立孢子形成细菌B。枯草杆菌，用于农业，定殖根。在我们的第一个目标中，我们将探索植物如何吸引B。枯草芽孢杆菌向其根，什么是细胞机制和分子参与这一过程。此外，我们将确定植物和它们的生长阶段，是特别有效的吸引B。枯草杆菌。这些实验的结果将为优化B的使用提供有用的指导。枯草杆菌为基础的生物肥料在田间，通过指出哪些条件将有利于B。枯草对根部的吸引力。在我们的第二个目标中，我们想了解植物根刺激B形成的机制。枯草杆菌多细胞群落，称为生物膜。我最近证明了存在于根细胞外的糖可以刺激B B。枯草杆菌生物膜形成。虽然这一发现在细菌-植物相互作用的研究领域产生了重要影响，但所涉及的细胞机制仍然未知。我们将进一步探讨这一现象，以提供新的见解的机制，B。枯草芽孢杆菌在根上建立了一个健壮的群落。此外，生物膜形成是细菌，特别是人类病原体的普遍存在的特征，并且是临床环境中的重要关注点。通过详细研究细菌生物膜在生命和变化表面上的形成，这是根源，我的研究小组将增加我们对多细胞宿主存在下形成的生物膜的理解。这些信息将是非常重要的，特别是在摆脱医院出生的持续性感染，这往往是通过生物膜形成维持。本研究计划第三个目标旨在鉴定新的B。枯草杆菌基因和分子过程所需的建立强大的相互作用与根。这些信息将为我们提供更有效的工具，以分离新的、更有效的生物肥料细菌，并设计具有更活跃的根缔合途径的有益菌株。综上所述，该项目将对加拿大和国际上的细菌-植物相互作用和生物膜形成的基础和应用研究产生积极的影响。这项研究将产生涉及细菌生物膜的跨王国相互作用的基础知识，这些知识应该可以翻译为医院环境中存在的许多病原体。此外，它还将立即应用于优化我们对B的使用。枯草芽孢杆菌作为生物肥料和潜在开发更有效的生物肥料。

In the soil, plant roots live in association with an important amount of bacteria. Some of them provide beneficial activities for the plant in exchange of the nutrients secreted by the root. These bacteria can notably promote plant growth and health by modulating its metabolism and by fighting pathogens. Beneficial microbes are starting to be used as biofertilizers and biopesticides worldwide, and constitute a very interesting and sustainable alternative to chemicals fertilizers and pesticides. While bacterial-based fertilizers are promising, much room is available to improve them. However, the current lack of fundamental knowledge on how these microbes approach and colonize the roots considerably slows down the improvement of biofertilizers’ usage and formulation. My research project proposes to establish how the spore-forming bacterium B. subtilis, used in agriculture, colonizes the root. In our first objective, we will explore how the plants attract B. subtilis toward its root, and what are the cellular mechanisms and molecules involved in this process. Also, we will identify the plants and their growth stage that are particularly potent in attracting B. subtilis. Results from these experiments will provide useful guidelines to optimize usage of B. subtilis – based biofertilizers in the field, by indicating which conditions will favor B. subtilis attraction toward the roots. In our second objective, we want to understand the mechanisms by which the plant roots stimulates formation of B. subtilis multicellular communities, termed biofilms, on its surface. I recently showed that the sugars constitutively present outside the roots’ cells stimulate B. subtilis biofilm formation. While this discovery had important impacts in the field of research on bacterial-plant interaction, the cellular mechanisms involved are still unknown. We will further explore this phenomenon to provide novel insights on the mechanisms by which B. subtilis establish a robust community on roots. Additionally, biofilms formation is a ubiquitous feature of bacteria, notably human pathogens, and is an important concern in clinical settings. By examining in detail bacterial biofilm formation on the living and changing surface that is the root, my research group will increase our comprehension of the biofilms formed in presence of a multicellular host. These informations will be of great importance notably in getting rid of hospital-born persistent infections, which often is maintained via biofilm formation. The third objective of this research program aim at identifying novel B. subtilis genes and molecular processes required for establishing a robust interaction with the root. These information will give us more potent tools to isolate new and more efficient biofertilizers bacteria and to engineer beneficial strains with more active root-association pathways. In summary, this proposed project will have many positive impacts on fundamental and applied research in the research field of bacterial-plant interaction and biofilm formation both at the canadian and international levels. This research will generate fundamental knowledge on cross-kingdom interactions involving bacterial biofilms, which should be translatable to many pathogens present in hospital settings. Additionally, it will also have immediate applications in optimizing our usage of B. subtilis as a biofertilizer and in potentially developing more potent biofertilizers.