Nutrients, temperature, and oxygen mediate microbial antibiotic resistance in sea bass (Lateolabrax maculatus) ponds

Antibiotic resistance genes (ARGs) have drawn increasing attention as novel environmental pollutants because of the threat they impose on human and animal health. The sea bass (Lateolabrax maculatus) is the third most cultured marine fish in China. Therefore, a study of ARG pollution in the sea bass culture environment is of great significance for the healthy and sustainable development of the sea bass industry. Here, we systematic investigated the contents of 23 antibiotic resistance-related genes (ARRGs), including 19 ARGs and four mobile genetic elements, and analyzed bacterial community composition and environmental parameters in sea bass ponds. The relative abundance (ARRG copies/16S ribosomal RNA gene copies) of ARRGs was up to 3.83 × 10^-2. Sul1 was the most abundant ARRG, followed by ereA, intI-1, sul2, dfrA1, and aadA. Both the ARRG changes and aquatic microbiota succession were mainly driven by water temperature (WT), dissolved oxygen (DO), and NO₃^-. WT is positively correlated with the most ARGs and some of the top 38 Operational Taxonomic Units (OTUs) belonging to the orders of Frankiales, Micrococcales, Chitinophagales, and Sphingomonadales. Furthermore, WT is negatively related with some other OTUs of the orders Frankiales, Xanthomonadales, Micrococcales, and Rhizobiales. However, DO and NO₃^- have the opposite function with WT on specific taxa and ARGs. These results indicate that sea bass ponds are reservoirs of ARGs, and are driven mainly by the nutrient, temperature, and oxygen with inducing specific microbial taxa. The regulation of environmental factors (increasing DO and NO₃^-) can be conducted to reduce drug resistance risk in aquaculture ponds. Therefore, environmental factors and specific taxa could be the indicators of ARG contamination and can be used to establish an antibiotic elimination system and consequently realize a sustainable aquaculture industry.