Distribution and influencing factors of antibiotic resistance genes in two mussel species along the coasts of the East China Sea and the Yellow Sea.

Antibiotic resistance genes (ARGs) raise a global public health concern. The ARGs profile in marine aquaculture environments was well reported, yet it is poorly revealed in marine bivalves. This study investigated the microbiota, resistome, and environmental factors within the digestive glands of two mussel species (Mytilus coruscus and Mytilus galloprovincialis) cultivated in the East China Sea and Yellow Sea. The microbial communities in the digestive glands of mussels exhibit significant variations across different sampling sites and between the two seas. The three bacterial phyla that predominated in all samples were Firmicutes, Bacteroidota, and Proteobacteria. A total of 88 ARGs were detected, with aminoglycoside resistance genes and multidrug resistance genes being the dominant categories. Analysis revealed that the quinolone resistance gene qnrB, associated with clinically relevant human pathogens, was ubiquitous in all samples. Members of the Enterobacteriaceae family may serve as a reservoir for qnrB within the investigated environment. The distribution of ARGs shows potential associations with the composition of microbial communities in the digestive glands, environmental factors, and mobile genetic elements (MGEs). These findings enhance the elucidation of microbial ecology and antibiotic resistance in marine aquaculture.