Pseudomonas spp.-based synthetic microbial community effects on nutrient dynamics in citrus plants under induced dysbiosis

A targeted Pseudomonas-based synthetic microbial community reshaped rhizosphere bacterial communities and altered potassium partitioning under stress conditions, suggesting a potential role in mitigating antibiotic-induced dysbiosis. Sustainable agriculture primarily relies on biological practices to improve crop yield and resilience. Synthetic bacterial communities (SynComs) are a promising approach to promote plant growth; however, their effectiveness in situ is influenced by interactions with native microbial ecosystems and by environmental stressors, such as low pH and antibiotic use. In this context, beneficial microorganisms like Pseudomonas may enhance nutrient availability and mitigate antibiotic-induced dysbiosis by supporting microbial community reassembly and functional stability, thereby improving plant health. This study evaluated the effects of a Pseudomonas-based SynCom on nutrient accumulation and rhizosphere microbial dynamics in citrus plants subjected to streptomycin-induced dysbiosis and low-pH conditions. Selected Pseudomonas strains, chosen for their compatibility and adaptability to low-pH conditions, and through whole-genome sequencing, were applied at equal concentrations (OD₆₀₀ = 0.1). SynCom treatment increased Chloroflexota abundance in the rhizosphere while reducing Actinomycetota and Pseudomonadota after 24 days. By Day 45, the abundance of Actinomycetota decreased, with slight increases in the other two phyla. At the genus level, SynCom application reduced the abundance of Pseudomonas and Agrobacterium, while enriching the Klebsiella community. Plants treated with SynCom under stress exhibited a 25% increase in leaf potassium levels, accompanied by a 29% decrease in root potassium (essential for stomatal regulation, osmotic adjustment, and photosynthetic efficiency, which are fundamental to tree growth and stress resilience) levels. Overall, our findings demonstrate that a targeted Pseudomonas-based SynCom can reshape rhizosphere communities and improve nutrient dynamics under abiotic stress, highlighting its potential as a sustainable strategy to mitigate antibiotic-induced dysbiosis and enhance citrus resilience.