Globally Distributed\nShale Gas Extraction Flowback\nand Produced Water Serves as a New Hotspot for Antibiotic Resistance\nGenes

Wastewaters with antibiotic residues are recognized as\npotential\n“hotspots” for antibiotic resistance genes (ARGs) due\nto their release of ARGs into the environment. Meanwhile, nonantibiotic\nwastewater may also serve as ARG hotspots, driven by other selective\npressures fostering ARG development. Flowback and produced water (FPW),\na byproduct of global shale gas extraction, harbors diverse ARG selective\npressures and rich microbial communities, making it an ideal environment\nfor ARG screening. This study characterized ARG profiles in FPW using\nmetagenomic sequencing, comparing them with established ARG hotspots\nto assess FPW’s potential as an ARG hotspot. The findings revealed\nthat (1) FPW exhibited a substantial abundance of ARGs, approximately\n1.8 times higher than that in natural environments, such as soil,\nnatural water, and natural sediment; (2) clinically relevant ARGs\nwere prevalent in FPW; (3) ARGs in FPW exhibited high mobility; and\n(4) diverse hosts of ARGs identified in FW included human pathogens.\nIn summary, the ARG profile in FPW fulfills all the criteria defining\nan ARG hotspot. Consequently, we posit for the first time that FPW\ncould be a novel ARG hotspot, emphasizing the need to underscore health\nrisks associated with ARGs in future shale gas extraction activities.