Sorghum rhizosphere bacteriome studies and generation of multistrain beneficial bacterial consortia

The plant rhizosphere microbiome plays a crucial role in plant growth and health. Within this microbiome, bacteria dominate, exhibiting traits that benefit plants, such as facilitating nutrient acquisition, fixing nitrogen, controlling pathogens, and promoting root growth. This study focuses on designing synthetic bacterial consortia using key bacterial strains which have been mapped and then isolated from the sorghum rhizosphere microbiome. A large set of samples of the rhizosphere bacteriome of Sorghum bicolor was generated and analyzed across various genotypes and geographical locations. We assessed the taxonomic composition and structure of the sorghum root-associated bacterial community identifying the most prevalent and keystone taxa. A set of 321 bacterial strains was then isolated, and three multi-strain consortia were designed making use of the bacteriome data generated using culture independent methodology. Subsequently, co-existence and plant-growth promoting ability of three bacterial consortia were tested both in vitro and in planta. Consortia 3 promoted plant growth in growth-chamber conditions while Consortia 1 and 2 performed better in field-plot experiments. Despite these differences, bacterial community profiling confirmed the colonization of the inoculated consortia in the sorghum rhizosphere without significant alterations to the overall bacterial community compared to the non inoculated ones. In summary, this study focused on a method, using root bacteriome data, to design and test bacterial consortia for plant beneficial effects with the aim of translating microbiome knowledge into applications.