Metagenomic analysis of microbial diversity and antibiotic resistance gene distribution in coastal mariculture systems of Jiangsu Province

In recent years, the rapid development of aquaculture has involved extensive antibiotic use. While ensuring production, it has also led to microbial community imbalance and the spread of antibiotic resistance genes (ARGs) in aquaculture environments. To elucidate the characteristics and mechanisms of these risks, this study employed metagenomic techniques to systematically analyze the distribution patterns of microbial diversity, ARGs, and mobile genetic elements (MGEs) in 3 types of mariculture water bodies (fish, shrimp, and crab) along the coast of Jiangsu Province, China. The results revealed significant differences in microbial composition among the different aquaculture types, with crab and shrimp cultures exhibiting higher microbial diversity than fish. The diversity analysis of ARG types in the resistance category indicates that in crab aquaculture water, genes conferring resistance to cephalosporins account for the highest proportion, and MGEs are predominantly active transposases; in fish aquaculture water, a complex ARG-MGE interaction network exists, within which Acinetobacter baumannii , a specific human health risk marker, was discovered; shrimp aquaculture water had the highest ARG abundance. At the same time, a tetracycline resistance gene cluster centered on tetA was formed. Besides multidrug resistance genes, cephalosporin resistance genes had the highest proportion of ARG numbers among all 3 water bodies. Horizontal gene transfer mediated by MGEs exacerbated the spread of resistance. This study provides a theoretical basis for understanding resistance evolution and ecological risk assessment in mariculture environments.