Degradation of chromosomal and plasmid encoded extracellular and intracellular resistance genes across different types and sizes in water matrices during ozone-based oxidation process

Antimicrobial resistance is a major and growing threat to public health and imposes significant environmental and economic burden worldwide. This study evaluates the degradation kinetics of resistance genes from ciprofloxacin (gyrA (R)), levofloxacin (qnrS (R)), tetracycline (tetA (R)), and mobile genetic elements (intl-1, plasmids) in water matrices by O-3 treatment. For extracellular antibiotic resistance genes (e-ARGs) in deionized water, 3.6-5.2 logs removal was obtained, whereas intracellular ARGs (i-ARGs) in phosphate buffer saline, exhibited a removal of 3.5-4.5 logs at an O-3 dosage of 3.7 x 10(-2) M.s. While there was no significant impact of the wastewater matrix on e-gyrA (R) and e-intl-1 degradation as compared to deionized water (p > 0.05), the e-qnrS (R) reduction was higher (4.8-5.2 logs) at an ozone dosage of 3.7 x 10(-2) M.s. For i-plasmid and e-plasmid encoded ARGs in wastewater, 4.0-5.5 logs removal was observed for the same dosage. Electrical Energy per Order (EEO, kWh/m(3)) was estimated, and the energy consumption on the degradation of the ARGs in the wastewater ranged between 0.68 and 1.1 kWh/m(3). The findings of this study provide quantitative data for evaluating the fate and degradation of different ARG forms/types during ozone treatment of wastewater to mitigate the risk of AMR dissemination in the environment.