A Bacillaceae consortium positively impacts arbuscular mycorrhizal fungus colonisation, plant phosphate nutrition, and tuber yield in Solanum tuberosum cv. Jazzy

In soils, phosphorus (P) is present in relatively large amounts, but for plants and microorganisms, P remains complexed under unavailable forms. To access the unavailable forms of P, plants interact with soil microorganisms such as arbuscular mycorrhizal fungi (AMF) and phosphate degrading bacteria (PDB) that can act synergically to improve plant P nutrition. In practice, we aim to stimulate microorganism properties for phosphate degradation and transport to the plant in agricultural soils. Firstly, 17 bacterial isolates were characterized for their ability to degrade insoluble P complexes and plant growth promoting rhizobacteria (PGPR) traits such as the production of auxins and the formation of biofilms via the production of extracellular polymeric substances. Secondly, two Bacillaceae isolates were selected regarding their compatibility in co-culture and ability to promote PGPR traits. In the greenhouse and in pots containing an agricultural soil, tubers of Solanum tuberosum cv. Jazzy were inoculated with each individual isolate, and both isolates. We showed that bacterial inoculation positively impacted plant P nutrition, growth, and yield as well as indigenous arbuscular mycorrhizal rate. Our results suggest that the bacterial consortium synergically interacts with indigenous AMF community to improve plant P nutrition and yield, without changing associated microbial communities.