摘要
      由于重金属、抗生素甚至耐药病原体的存在，直接排放水产养殖废水可能会产生毒性影响，但很少受到关注。在这里，建立了模拟野生生态系统的水箱，以研究长期暴露于含有土霉素（OTC）和/或砷（As）的鸭子废水对热带爪蟾生长、生理功能和肠道微生物群进化的影响。结果表明，鸭子废水对热带X.tropicalis没有明显影响，但随着OTC和/或As的暴露，影响显著增加（P<0.05），尤其是对体重和生长速度的影响。生化指标显示，暴露72天后，所有治疗组的热带X.都有不同程度的氧化应激损伤、肝毒性（炎症、坏死和血窦）和胶原纤维化，这间接抑制了热带X.的生长。此外，16S rDNA扩增子测序结果表明，长期暴露后肠道微生物群结构和代谢功能受到干扰，这可能是生长抑制的主要原因。有趣的是，由于鸭废水中应激因素的直接和间接影响，肠道抗性基因（RGs）的丰度随着暴露时间的增加而增加。此外，一旦RGs表达，抗性至少持续24天，尤其是由tetA赋予的抗性。这些结果证明了含DW的OTC（0.1–4.0 mg/L）和/或As（0.3–3.5µg/L）对两栖动物的毒性作用，并表明限制农场重金属和抗生素的使用以控制废水的生物毒性至关重要。
Abstract
Direct discharge of aquaculture wastewater may have toxic effects, due to the presence of heavy metals, antibiotics, and even resistant pathogens, but little attention has been given. Here, tanks simulating a wild ecosystem were built to study the effects of long-term exposure to duck wastewater containing oxytetracycline (OTC) and/or arsenic (As) on the growth, physiological function, and gut microbiota evolution of Xenopus tropicalis. The results showed that duck wastewater had no apparent impact on X. tropicalis, but the impact increased significantly (P < 0.05) with exposure to OTC and/or As, especially the impact on body weight and growth rate. Biochemical indicators revealed varying degrees of oxidative stress damage, hepatotoxicity (inflammation, necrosis, and sinusoids), and collagen fibrosis of X. tropicalis in all treated groups after 72 days of exposure, which indirectly inhibited X. tropicalis growth. Moreover, 16S rDNA amplicon sequencing results showed that the gut microbiota structure and metabolic function were perturbed after chronic exposure, which might be the leading cause of growth inhibition. Interestingly, the abundance of intestinal resistance genes (RGs) increased with exposure time owing to the combined direct and indirect effects of stress factors in duck wastewater. Moreover, once the RGs were expressed, the resistance persisted for at least 24 days, especially that conferred by tetA. These results provide evidence of the toxic effects of DW containing OTC (0.1–4.0 mg/L) and/or As (0.3–3.5 µg/L) on amphibians and indicate that it is vital to limit the usage of heavy metals and antibiotics on farms to control the biotoxicity of wastewater.

https://www.sciencedirect.com/science/article/abs/pii/S1001074222002972