摘要
      抗生素和沉积物都会影响水生系统的反硝化作用。然而，在沉积物存在的情况下，抗生素是如何影响反硝化作用的，目前还知之甚少。本文研究了抗生素（磺胺甲恶唑、四环素和氧氟沙星）在不存在和存在沉积物的情况下对反硝化作用的影响。通过对反硝化功能基因（DNGs）、细菌16S-seq和抗生素抗性基因（ARGs）的定量分析，揭示了其影响机制。结果表明，抗生素的存在通过降低narG、nirK、nosZ、总DNG和反硝化细菌的丰度来抑制NO3-N的减少。然而，沉积物减轻了抑制作用，促进了细菌的生长，降低了抗生素作为细菌和抗生素载体的选择压力，从而增加了反硝化细菌和所有DNG的丰度。偏最小二乘路径模型揭示了抗生素对细菌、ARGs和DNG具有负面影响，而沉积物对ARGs具有负面影响但对细菌和DNG有正面影响。网络分析进一步揭示了芽孢杆菌属、不动杆菌属和肠杆菌属与ARGs和DNGs的密切关系。这些发现有助于了解抗生素污染的天然水中的反硝化作用。
Abstract
Both antibiotics and sediments can affect the denitrification in aquatic systems. However, little is known how antibiotics influence the denitrification in the presence of sediments. Here, the effects of antibiotics (sulfamethoxazole, tetracycline and ofloxacin) on denitrification in the absence and presence of sediments were investigated. The influencing mechanisms were revealed by quantifying the denitrification functional genes (DNGs), 16S-seq of bacteria, and antibiotic resistance genes (ARGs). The results showed that the presence of antibiotics inhibited NO3-N reduction by decreasing the abundances of narG, nirK, nosZ, total DNGs, and denitrifying bacteria. However, the inhibition effect was alleviated by sediments, which promoted the growth of bacteria and decreased the selective pressure of antibiotics as the vector of bacteria and antibiotics, thus increasing the abundances of denitrifying bacteria and all the DNGs. Partial least-squares path model disclosed that antibiotics had negative effects on bacteria, ARGs and DNGs, while sediments had negative effects on ARGs but positive effects on bacteria and DNGs. The network analysis further revealed the close relation of the genera Bacillus, Acinetobacter, and Enterobacter with the ARGs and DNGs. The findings are helpful to understand the denitrification in antibiotic-polluted natural waters.

https://www.sciencedirect.com/science/article/abs/pii/S0048969721051676