Effective colonisation by a bacterial synthetic community promotes plant growth and alters soil microbial community

Introduction: Plant-associated microorganisms are widely explored for their use as bioinoculants in agriculture. However, the rate and ability of introduced microbes to colonise and interact with indigenous soil microbiomes are largely unknown. Materials & Methods: In this study, we constructed a bacterial synthetic community (SynCom) using eight plant-growth-promoting bacteria isolated from the wheat (Triticum aestivum) rhizosphere, including three Bacillus spp., two Acinebacter spp., an Enterobacter sp., a Xanthomonas sp. and a Burkholderia sp., which all showed multiple plant growth-promoting effects including indole-3-acetic acid and ammonia production and fungal pathogen suppression. We inoculated this SynCom in a soil with reduced microbial diversity, and investigated the ability of the SynCom to colonise wheat plants, and interact with soil microbes in the presence or absence of a soil-borne pathogen Fusarium pseudograminearum (Fp). Results: We found that SynCom significantly increased the wheat plant growth, root development and biomass production. Fp load in soil was significantly reduced and plant survival rates increased following the SynCom inoculation. Soil microbial community structure was altered by the SynCom, and noticeably, relative abundance of Pseudomonas spp. was induced in the soil. Conclusion: This study provides novel evidence that colonisation of a beneficial SynCom promotes plant growth and alters soil microbial community.