Regulation of antibiotic resistance genes dissemination by in situ formed iron sulfide nanoparticles in anaerobic microbial communities.

The aim of this study was to investigate the mechanisms of in situ-synthesized iron sulfide nanoparticles (bio-FeS NPs) on the dissemination of antibiotic resistance genes (ARGs) in anaerobic microbial consortia. The absolute abundance of plasmid RP4-associated extracellular ARGs (eARGs) decreased by more than 103 copies/ng DNA in the anaerobic consortia containing in situ-formed bio-FeS NPs (AnBR-FeS NPs). Mechanistic analysis revealed that the inhibitory effect was related to the absence of a significant correlation between functional bacteria such as Nitratidesulfovibrio in AnBR-FeS NPs and Escherichia carrying the RP4 plasmid, as well as a 2.21-fold increase in calcium/magnesium adenosine triphosphatase and a 1.86-fold reduction in reactive oxygen species levels. Notably, co-occurrence analysis indicated that bio-FeS NPs preferentially maintained cellular homeostasis, reducing the dependence of ARG propagation on mobile genetic elements. This study provides new insights into the role of in situ nanominerals in suppressing ARG dissemination in anaerobic wastewater treatment systems.