Occurrence and Composition Patterns of ARGs in Plant-Microbial Synergism Were Negatively Reconstructed by an Electrochemical Technology at Low Temperatures

Electrochemical technology has been proven to significantly improve the performance of ecological treatment technology for the removal of antibiotics and antibiotic resistance genes (ARGs). However, how electrochemical technology affected the occurrence of ARGs in multimedia of ecological treatment technology, especially at low temperatures, is still a knowledge gap. In this study, the electrochemically coupled plant-microbial system at low temperatures was built to decipher the occurrence, mobility, and hosts of ARGs in multimedia under sulfamethoxazole selection pressure by metagenomic assembly and binning. Our results indicated that intracellular ARGs (iARGs) were higher than extracellular ARGs (eARGs) in effluents. Raising the voltage (10 V) reduced the abundance of iARGs but increased the abundance of eARGs. Electrochemical technology increased the abundance of ARGs in multimedia, and the iron ion was the key contributor. Microcurrent increased the transfer frequency of ARG-carrying contigs (ACCs), but iron ions decreased the proportion of ACCs on plasmids. Electrochemical technology changed the representative combinations of ARGs and MGEs. Iron plaque in roots is a hot spot for the enrichment of ARGs due to the provided adsorption sites for microbial proliferation. We found that electrochemical technology at low temperatures can increase the cumulative risk of ARGs in ecological treatment technology, which deepened our insights into the safety of the electrochemically enhanced ecological treatment technology at low temperatures.