Bacterial consortia for increase nitrogen fixation in agricultural soil

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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.