Deciphering key traits and dissemination of antibiotic resistance genes and degradation genes in pharmaceutical wastewater receiving environments

Abstract

Discharge of pharmaceutical wastewater significantly affects the receiving environments. However, the development of antibiotic resistance and microbial enzymatic degradation in wastewater-receiving soils and rivers remains unclear. This study investigated a sulfonamide-producing factory to explore the distribution of antibiotic resistance genes (ARGs) in the receiving river and soil environments (0–100 cm depth), and the potential hosts of sadABC genes (sulfonamide-degrading genes) as well as their phylogenetic characterization. We identified plentiful ARGs (28 types and 1065 subtypes) and their hosts (30 phyla and 340 MAGs) in three media (surface water, sediment, and soil). Results indicated that the abundances of total resistome in water and sediment of receiving river (0–1.5 km) were higher than the global river resistome median levels. Wastewater significantly affected the soil resistome, leading to an average 5-fold increase in ARG abundance, and a 22-fold enrichment of sulfonamide ARGs. The abundance and diversity of soil resistome decreased significantly with depth, and the abundance was below the global soil resistome median level at the depth greater than 20 cm. The detection of 17 risk rank I ARGs and the enrichment of multidrug-resistant pathogenic bacteria in soil and river highlighted the resistance risks in the environments. Notably, 73 sadABC-carrying contigs were detected, which were mainly hosted by Microbacteriaceae and some other previously unreported bacteria, such as Mycobacteriaceae spp. The findings offer valuable insights into antimicrobial resistance (AMR) risk assessment and the bioremediation of sulfonamides pollution in the environment affected by pharmaceutical wastewater.