Determination and optimization of Bacillus subtilis traits required for its establishment, persistence and activities on plant roots

微生物对生物生态系统的健康至关重要。因此，使用有益于植物的细菌作为有机改良剂，在农业中促进生长和保护病原体，是目前过度使用化学品的一个有前途的替代方案。虽然这些产品中的许多已经上市，但它们的功效不一致是它们在田间和温室中广泛使用的主要障碍。来自芽孢杆菌属的细菌，特别是枯草杆菌和绒毛杆菌属的细菌，在农业中生物解决方案的开发中具有重要意义。这些细菌具有许多促进植物生长(PGP)的特性，如直接刺激植物的新陈代谢，并帮助植物获得多种营养。大多数芽孢杆菌物种分泌大量的抗菌剂，有利于植物对病原菌的侵染，因此可以作为天然的生物杀虫剂和杀菌剂。芽孢杆菌还可以形成耐药的内孢子，这是一种适合产品配方的休眠状态。关于有益的芽孢杆菌和植物之间的相互作用的基本问题仍然没有得到回答，这减缓了我们形成一致有效产品的能力。在这个研究项目中，我们将探索三个基本问题，目的是更好地了解芽孢杆菌物种与植物之间的复杂相互作用。首先，我们将确定哪些环境条件调节了芽孢杆菌在根上的休眠。在同样的目标中，我们还将评估芽孢杆菌孢子是否仍然可以对植物产生有益的影响。其次，我们将确定在没有竞争菌株和存在竞争菌株的情况下，哪些芽孢杆菌细胞成分对根部的建立和持续至关重要。最后，我们将评估芽孢杆菌在植物根部的有益活性表达到什么程度，以及如何在自然条件下增强它们的活性。本研究将有助于从根本上了解枯草芽孢杆菌与植物的相互作用，为今后这种生物生长促进剂和农药的开发、使用和配方提供关键信息。这些知识非常重要，因为它们对于发展和种植可持续农业系统是必要的。

Microorganisms are essential for the good health of biotic ecosystems. Thus, use of plant-beneficial bacteria as organic amendments for increase growth and pathogen protection in agriculture is a promising alternative to the current over-usage of chemicals. While many of these products are already on the market, inconsistence in their efficacy is a major hurdle to their widespread usage in fields and greenhouses. Bacteria from the Bacillus genera, and in particular of the subtilis and velezensis species, are of central interest in the development of biological solutions in agriculture. These bacteria possess many plant growth-promoting (PGP) traits, such as direct stimulation of the metabolism of the plant, and aid for the plant to acquire diverse nutrients. Most Bacillus species secrete an arsenal of antimicrobials and favor the plant resistance's toward pathogen infections, thus acting as natural, biological pesticides and fungicides. Bacillus species can also form resistant endospores, a dormant state ideal for product formulation. Fundamental questions about the interaction between beneficial Bacillus and plants are still unanswered, which slows down our capacity to formulate consistently efficient products. In this research program, we will explore three fundamental questions with the aim of better understanding the complex interactions between Bacillus species and plants. First, we will determine what are the environmental conditions that modulate dormancy of Bacillus on roots. In the same objective, we will also evaluate if Bacillus spores can still exert beneficial effects on plants. Secondly, we will identify what are Bacillus cellular components that are critical for the establishment and persistence on roots in absence and in presence of competing strains. Finally, we will evaluate to what extent Bacillus beneficial activities are expressed when it is on plant roots, and how to potentiate their activities in natural conditions. This research program will lead to a fundamental comprehension of in planta interactions of B. subtilis and plants, providing key information for the future development, usage and formulation of this biological growth promoter and pesticide. These knowledge are very important, since they are necessary to develop and implant sustainable agricultural systems.