Dynamics of microbial communities and functional genes under the interactions between phosphorus inactivation agents and phosphorus-solubilizing bacteria in sediments

Abstract

The interactions between phosphorus inactivation agents (PIAs) and phosphate-solubilizing bacteria (PSB) profoundly influence the transformation and migration of phosphorus at the sediment–water interface. However, the effects of PIA application on the community structure of PSB and the associated phosphorus-related functional genes in sediments remain poorly understood. Here, we demonstrate that PIA alone increases PSB community complexity, but combined with PSB, it simplifies structures via competitive pressure while suppressing organophosphorus ester hydrolysis genes (e.g., phoN, phnX) and activating oxidative phosphorylation pathways. According to the metagenomic study, Bacteroidota triggered phosphonate metabolism (e.g., C-P lyase) during PIA treatment, whereas Pseudomonadota dominated natural sediments (∼80 % relative abundance) and used oxidative phosphorylation to liberate phosphorus. Contrary to previous assumptions of sustained PIA efficacy, our long-term experiments revealed a resurgence of Pseudomonadota, indicating microbial adaptability counteracts initial remediation effects. High-dose PSB enhanced phosphate transporter gene expression (pstBC, ugpC) yet synergized with PIA to stabilize residual phosphorus forms. These findings redefine the temporal limitations of PIA and highlight microbial feedback as a key driver of phosphorus re-release. By integrating metagenomics and phosphorus speciation, this study bridges microbial adaptability with PIA-based sediment remediation, offering insights into microbes and dosage balance determining long-term success in eutrophication control.