Degradation of extracellular antibiotic resistance genes in water and their degradation prediction using a...

Understanding the environmental fate of extracellular antibiotic resistance genes (eARGs) is essential for assessing their persistence, mobility, and associated risks within the One Health framework. Here, the degradation kinetics of three representative eARGs were quantified under varied water quality conditions using real-time quantitative polymerase chain reaction (qPCR). Temperature, pH, and heterotrophic plate counts (HPC) were identified as dominant factors influencing eARG degradation. Elevated temperature, deviation from neutral pH, and increased microbial abundance significantly accelerated degradation, yielding first-order rate constants of 0.13-0.54 day^-1. Transformation frequencies of circular eARGs declined to undetectable levels within nine days-well before the disappearance of total DNA-revealing a temporal decoupling between genetic persistence and biological activity. A nonlinear multivariate model integrating temperature, pH, and HPC accurately predicted eARG degradation rate constants k (R² > 0.75) across diverse aquatic systems. This framework quantitatively links environmental conditions to eARG persistence and offers a scalable tool for rapid environmental risk evaluation and informed water quality management aimed at mitigating antibiotic resistance dissemination.