Strong suppression of silver nanoparticles on antibiotic resistome in anammox process.

This study comprehensively deciphered the effect of silver nanoparticles (AgNPs) on anammox flocculent sludge, including nitrogen removal performance, microbial community structure, functional enzyme abundance, antibiotic resistance gene (ARGs) dissemination, and horizontal gene transfer (HGT) mechanisms. After long-term exposure to 0–2.5 mg/L AgNPs for 200 cycles, anammox performance significantly decreased (P < 0.05), while the relative abundances of dominant Ca. Kuenenia and anammox-related enzymes (hzsA , nirK) increased compared to the control (P < 0.05). For antibiotic resistome, ARG abundance hardly changed with 0–0.5 mg/L AgNPs but decreased by approximately 90% with 1.5–2.5 mg/L AgNPs. More importantly, AgNPs effectively inhibited MGE-mediated HGT of ARGs. Additionally, structural equation model (SEM) disclosed the underlying relationship between AgNPs, the antibiotic resistome, and the microbial community. Overall, AgNPs suppressed the anammox-driven nitrogen cycle, regulated the microbial community, and prevented the spread of ARGs in anammox flocs. This study provides a theoretical baseline for an advanced understanding of the ecological roles of nanoparticles and resistance elements in engineered ecosystems. [Display omitted] • AgNPs effects on anammox flocs were comprehensively deciphered. • AgNPs inhibited anammox performance and regulated the microbial community. • The antibiotic resistome significantly decreased (> 80%) with 1.5-2.5 mg/L AgNPs. • AgNPs effectively prevented the MGE-mediated HGT of ARGs. • Ca. Kuenenia was found to be the potential host of aminoglycoside gene aadA6. [ABSTRACT FROM AUTHOR]