Visible-Light-Activated Removal of Antibiotic Resistance Genes Using Electrospun Plasmonic Photocatalyst of Carbon Nitrides and Silver Nanoparticles

Antibiotic resistance genes (ARGs) pose a critical global health threat, driving the emergence of antibiotic-resistant bacteria (ARB) and causing an estimated 7,00,000 deaths annually. While current wastewater treatment technologies significantly reduce bacterial loads, residual ARGs in effluent highlight the need for advanced, targeted solutions. Plasmonic photocatalysts, leveraging localized surface plasmon resonance of nanoparticles provide an innovative solution by generating high-energy charge carriers (“hot” electrons and holes) under visible light. Despite their promise, the application of plasmonic photocatalysts for ARG removal remains underexplored. This study introduces a composite plasmonic photocatalyst comprising silver (Ag) nanoparticles, graphitic carbon nitride (g-C₃N₄), and polyvinylidene fluoride nanofibers. Characterized by a bandgap energy of 2.89 ± 0.06 eV and optimized for visible light activation, this material addresses limitations of traditional photocatalysts. Real wastewater samples from a primary clarifier effluent at a South Dakota Water Reclamation Facility were analyzed. A custom photostation equipped with chips-on-board light-emitting diode (2,87,000 lux) and a cassette-type photocatalytic mat enclosed in identical Teflon sheets (2 cm × 2 cm window) was utilized. Microbial community analysis and microfluidic-based qPCR revealed the presence of 29 ARGs, 6 heavy metal resistance genes (HMRGs), and 7 integrase-encoding genes in the primary clarifier effluent. Key genes, including ermB, ermF, intl1, intl3, merA, qacF, strB, sul1, and tetX were detected at abundances exceeding 5 log₁₀ gene copies/µL, indicating coselection mechanisms. Plasmonic photocatalyst treatment significantly reduced critical bacterial groups, including Epsilonproteobacteria, Bacteroides, and Leptrichiaceae. Specific ARGs, including vanA and qnrA, showed substantial reductions, with differences in the copy numbers of bla_NDM-1, bla_SHV, bla_imp13, qnrA, tetM, tetL, dfr13, vanA, and mexB. Importantly, the treatment mitigated ARB and ARGs without impacting HMRGs and integrase genes. This photocatalytic approach demonstrates potential as a supplementary treatment strategy for targeting ARGs in wastewater systems, particularly under visible and ambient light conditions. This study introduces an innovative approach to wastewater treatment using light-activated membranes to mitigate ARGs.