Fate of high-risk antibiotic resistance genes in large-scale aquaculture sediments

As emerging environmental contaminants, antibiotic resistance genes (ARGs) have become global public health security issues. However, the distribution and drivers of ARGs, especially high-risk ARGs, in large-scale aquaculture sediments remain unclear. Here, we collected sediment samples from 40 crayfish ponds in major crayfish farming provinces of China to investigate the distribution and risk of ARGs based on 16S rRNA gene sequencing and high-throughput quantitative PCR techniques. The results showed that aquaculture sediment was potential reservoir for ARGs and the abundance of aadA-02 was the highest. High-risk ARG (floR) was also prevalent in the sediment and was most abundant in Jiangsu Province, where opportunistic pathogens were also enriched. The abundance of floR was positively correlated with different environmental factors, such as TPW and TCS. In addition, opportunistic pathogenic bacteria (Mycobacterium) might be potential hosts for ARGs, including high-risk ARGs. Furthermore, there was the potential propagation pathway of ARGs from sediment to crayfish gut, and Bacteroidetes and Proteobacteria may be the predominant bacteria for the proliferation of ARGs. Generally, our results illustrate that ARGs including high-risk ARGs are prevalent in sediment and the risk of ARGs in Jiangsu Province is higher than in other provinces. Meanwhile, our study helps develop valuable strategies for the risk assessment and management of ARGs.