Nitrogen Removal Performance and Microbial Response of Anammox Under Multiantibiotic Stress: Effect of Static Magnetic Field

Abstract

The long-term impacts of multiantibiotics (oxytetracycline and sulfadiazine) on the anaerobic ammonium oxidation (anammox) process were investigated, and the effectiveness of static magnetic field (SMF) in relieving the multiantibiotic stress was analyzed. Nitrogen removal efficiency and anammox activity were severely inhibited by multiantibiotic exposure, which was persistent and irreversible even after their removal from the influent. The relative abundances of antibiotic resistance genes (ARGs) related to antibiotic inactivation and efflux pumps exhibited substantial increases under multiantibiotic stress. The relative abundances of ARGs targeting sulfonamide and tetracycline represented only 6.7− 18.9% of the total abundance, with sul2 being the most prevalent ARG. Coexisting heterotrophic bacteria were identified as potential ARG hosts, while anammox bacteria, particularly Candidatus Kuenenia, exhibited negative correlations with most ARGs. Antibiotics and SMF appeared to play important roles in ARG evolution. SMF could relieve anammox inhibition by multiple antibiotics through improved aggregation of anammox granules and enhanced metabolism and environmental information processing.