摘要
      硝酸盐还原基因（NRGs）和抗生素抗性基因（ARGs）的微生物共宿主最近被报道，但它们在城市水道中的生态和生物化学作用在很大程度上仍然未知。在这里，我们采集了青藏高原湟水河丰枯水期的29个地表水和29个沉积物样本，以及沿线污水处理厂和湿地的11个水样。使用宏基因组测序，我们检索了278个NRG-ARG共宿主的中高质量宏基因组组装基因组（MAG），主要属于变形菌门、放线菌门和拟杆菌门。在携带ARGs的微生物中，高比例（75.3%-94.9%）也编码NRG，支持硝酸盐还原细菌作为ARGs主要宿主。抗生素水平的季节性变化与水和沉积物中NRG-ARG共宿主的相对丰度的显著变化相对应，从而导致抗生素耐药性途径的相应变化。相反，NRG-ARG共同宿主对硝酸盐还原的贡献在不同季节之间是稳定的。我们确定了可能对这些关系产生不成比例影响的特定抗生素（如磺酰胺类）和微生物类群（如不动杆菌和哈夫尼亚菌），作为生物修复策略实验室研究的基础。我们的研究表明，受污染环境中高度丰富的硝酸盐还原微生物也可能作为抗生素耐药性的携带者直接影响人类健康。
Abstract
Microbial co-hosts of nitrate reduction genes (NRGs) and antibiotic resistance genes (ARGs) have been recently reported, but their ecology and biochemical role in urban waterways remain largely unknown. Here, we collected 29 surface water and 29 sediment samples in the Huangshui River on the Qinghai-Tibet Plateau during the wet and dry season, and 11 water samples from wastewater treatment plants and wetlands along the river. Using metagenomic sequencing, we retrieved 278 medium-to-high-quality metagenome-assembled genomes (MAGs) of NRG-ARG co-hosts, mainly belonging to the phyla Proteobacteria, Actinobacteriota, and Bacteroidota. Of microorganisms carrying ARGs, a high proportion (75.3%‒94.9%) also encoded NRGs, supporting nitrate reducing bacteria as dominant hosts of ARGs. Seasonal changes in antibiotic levels corresponded to significant variation in the relative abundance of NRG-ARG co-host in both water and sediments, resulting in a concomitant change in antibiotic resistance pathways. In contrast, the contribution of NRG-ARG co-hosts to nitrate reduction was stable between seasons. We identify specific antibiotics (e.g., sulphonamides) and microbial taxa (e.g., Acinetobacter and Hafnia) that may disproportionately impact these relationships to serve as a basis for laboratory investigations into bioremediation strategies. Our study suggests that highly abundant nitrate reducing microorganisms in contaminated environments may also directly impact human health as carriers of antibiotic resistance.

https://www.sciencedirect.com/science/article/abs/pii/S0043135422011344