Sorghum rhizosphere bacteriome studies to pinpoint, isolate and assess plant beneficial bacteria

Background In the intricate relationship between plants and microorganisms, plant growth-promoting bacteria (PGPB) play a vital role in the rhizosphere. This study focuses on designing synthetic bacterial consortia using key bacterial strains mapped and isolated from the sorghum rhizosphere microbiome. Results A large set of samples of the rhizosphere bacteriome of Sorghum bicolor was analyzed across various genotypes and geographical locations. We assessed the taxonomic composition and structure of the sorghum root-associated bacterial community using 16S rRNA gene amplicon profiling, identifying key taxa and core-bacterial components. A set of 321 bacterial strains was then isolated, and three multi-strain consortia were designed by combining culturable and unculturable microbiome-derived information. Subsequently, co-existence and plant-growth promoting ability of three consortia were tested both in vitro and in planta . In growth-chamber and in-field experiments demonstrated that bacterial Consortia 3 promoted plant growth in growth-chamber conditions while Consortia 1 and 2 performed better in field-plot experiments. Despite these differences, 16S rRNA gene profiling confirmed the stable colonization of the inoculated consortia in the sorghum rhizosphere without significant alterations to the overall bacterial community. Conclusions This study aims at translating microbiome knowledge into applications by designing and testing microbiome-based multi-strain bacterial consortia in promoting sorghum growth.