Monitoring of antimicrobial resistance genes in the spotted sea bass (Lateolabrax maculatus): Association with the microbiome and its environment in aquaculture ponds

Antimicrobial resistance genes (ARGs) pose a serious threat to environment and human health. However, few studies address the abundance and distribution of ARGs associated with farmed fish and their aquaculture environment. Here we conducted an analysis of the abundance and distribution of gut and gill ARGs by quantitative PCR techniques associated with the spotted sea bass (Lateolabrax maculatus) as well as the bacterial communities in the surrounding environment (water and sediment). For this purpose, we sampled six aquaculture ponds in Zhuhai, Guangdong Province, the largest spotted sea bass cultivation site in China. Predominant ARGs were floR, sul2, and tetM-01 in the gut and tetQ, sul1 and floR in the gills. The copy numbers of sul1, sul2, and cmlA1-01 were significantly higher in the environment. Moreover, significant differences were found among the microbiota of the gut, gills, and environment. The former was more similar to those of the environmental microbial communities compared with other sources. The fish gut and gill microbiota were predominantly populated by Fusobacteria and Actinobacteria, respectively. In contrast, Proteobacteria were dominant in water and sediment. Correlation analysis showed that Fusobacteria and Actinobacteria positively correlated with floR and tetQ, respectively, indicating that these microbes were potential hosts for ARGs. Our results showed that ARGs in farmed fish showed marked difference with their aquaculture environment, thus providing a valuable reference for identifying deleterious ARGs in aquatic fish. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study found that the predominant ARGs in spotted sea bass were floR, sul2, and tetM-01, while sul1, sul2, and cmlA1-01 had significantly higher copy numbers in the environment. There were significant differences in the microbiota of fish gut, gills, and the environment, with Fusobacteria and Actinobacteria potentially acting as hosts for ARGs.