Unraveling Plasmid Contributions to Phosphorus Acquisition in Soil Microbiomes

Background Phosphorus (P) is a fundamental macronutrient for plant and microbial growth, but its availability in soils is often constrained by strong interactions with minerals and organic matter. While the role of bacteriophages in P cycling has gained attention, plasmids remain comparatively underexplored despite their central role in horizontal gene transfer. This study aimed to investigate the occurrence, diversity, and ecological relevance of plasmid-borne genes involved in P acquisition across soils with contrasting P availability. Results Using curated plasmid databases and soil metagenomes from diverse biomes, we identified a broad repertoire of plasmid-encoded P-acquisition genes. These genes encompassed regulatory pathways, transport systems, organic P mineralization, and inorganic P solubilization. Regulatory and transporter genes were the most abundant categories, with phoB , phoP , and ugpC among the most frequently detected. Significant differences in gene abundance were observed between high- and low-P environments. High-P tundra environments favored plasmids with more regulatory and transport genes compared to low-P tundra, while P-deficient soils generally showed higher abundances of P transport and organic P mineralization genes. Taxonomic assignment revealed that Pseudomonadota were the predominant plasmid hosts, followed by Bacillota and Actinobacteriota , suggesting broad host diversity. Conclusions This study underscores the ecological significance of plasmid-borne P-acquisition genes in P cycling and their potential in microbial adaptation to P-deficient soils. The dominance of Pseudomonadota and Bacillota as plasmid hosts highlights their central contribution to these processes. Overall, our findings expand the current understanding of plasmid involvement in soil fertility and point to their potential application in bioaugmentation strategies to enhance P use efficiency and promote sustainable agriculture.