In the field of microbial inoculants applied to soils to protect or promote plant growth, single microbial strains (either a bacterium or a fungus) are traditionally used. While these bioinoculants usually perform nicely in laboratory assays, their activity in soils is often inconsistent. Recent research has demonstrated that using a mixed inoculum, consisting of a fungus and one or several bacterial species, produces a more robust bioinoculant, with more consistent effects on plant growth promotion in soil. Therefore, such an approach could represent an alternative to agrochemicals to be applied in sustainable agriculture. In this project we aim at developing a new type of bioinoculant by releasing a consortium composed of bacteria and fungi that act as biocontrol agents against the generalist soil-borne plant pathogen Rhizoctonia solani, using lettuce as a model crop. Besides performance of the bioinoculant on plant growth under different environmental conditions, the effect of this product on the natural rhizospheric and root endophytic microbial communities associated to the plant will be assessed to verify their safety (invasive potential) when applied to natural soil communities.