Bacterial consortia for increase nitrogen fixation in agricultural soil

在大多数农业土壤中，生物可利用氮是有限的，通常需要通过使用化学添加剂人工提供。然而，可持续农业涉及减少这些化学产品在土壤中的应用。与植物根系相关的细菌可以通过生物固氮（BNF）活性来执行多种对植物有益的功能，包括提供生物可利用氮。因此，它们构成了生态友好型农业添加剂的有趣途径。在这个项目中，我们将利用我们最近发现的两种非常不同的细菌，一种植物生长促进（PGP）芽孢杆菌和一种固氮固氮细菌，在一起接种时相互影响。在没有氮的情况下，这种共接种可以使固氮细菌更好地固氮，并使芽孢杆菌的代谢活性增强。我们将研究这种细菌联合体，如果与植物接种，是否可以减少对化学物质的需求，如生物可利用氮。我们还将使用已知的对植物有益的菌株来配制其他类似的细菌联合体，并比较这些新型联合体在溶解几种矿物质微量营养素和固定氮方面的功效。同样，我们将通过筛选超过300对由有益细菌和共生固氮菌组成的细菌，来确定芽孢杆菌对自由生活的固氮细菌的这种有益活性是否可以转化为共生固氮细菌。与促进植物生长和微量营养素获取有关的活性将在体外确定，最有希望的联合体将在豆类上进行测试，以评估植物促进活性。该项目将与我们的工业合作伙伴Premier Tech一起进行，他们将协助我们使用他们收集的菌株筛选微生物群落，并在利用植物生长分析评估各种群落效率方面发挥主要作用。该项目将提供PGP细菌效力的信息，以提高共生固氮的使用，并将导致开发新的微生物接种剂，由Premier Tech配制，用于与加拿大有关的植物和农业环境。

Bioavailable nitrogen is limiting in most agricultural soils, and often need to be provided artificially via the use of chemical additives. However, sustainable agriculture involves a reduction of the application of these chemical products in soil. Bacteria associated with plant roots can execute multiple functions beneficial to plant, including providing bioavailable nitrogen, via a biological nitrogen-fixation (BNF) activity. Thus, they constitute an interesting avenue for ecologically-friendly agricultural additives. In this project, we will leverage our recent discovery that two very different bacteria, a plant growth-promoting (PGP) Bacillus and a nitrogen fixer Azotobacter, influence each other positively when inoculated together. In absence of nitrogen this co-inoculation leads to better nitrogen fixation by the nitrogen-fixing bacteria, and more metabolic activities by the Bacillus. We will examine if this bacterial consortia, inoculated with plants, could reduce the needs for chemicals such as bioavailable nitrogen. We will also formulate other similar bacterial consortia using strains already known for their plant-beneficial effects, and compare the efficacy of these novel consortia to solubilize several mineral micronutrients and to fix nitrogen. Similarly, we will determine if this beneficial activity of Bacillus on a free-living nitrogen-fixing bacteria can be translated to symbiotic nitrogen fixing bacteria, by screening over 300 pairs composed of beneficial bacteria and symbiotic nitrogen fixers. Activities related to plant growth promotion and micronutrient acquisition will be determined in vitro, and the most promising consortia will be tested on pulses to evaluate plant promotion activity. This project will be undertaken with our industrial partner Premier Tech, who will assist us in the screening of microbial consortia using strains from their collections and play a major role in the evaluation of the various consortia efficiency using plant growth assays in fields. This project will provide information on the potency of PGP bacteria to improve the usage of symbiotic nitrogen fixation, and will lead to the development of new microbial inoculants to be formulated by Premier Tech to be used on plants and agricultural context relevant to Canada.