Abstract：
Biofilters are the important source and sink of antibiotic resistance genes (ARGs) and antibiotic resistance bacteria (ARB) in the drinking water. Current studies generally ascribed the prevalence of BAR in biofilter from the perspective of gene behavior, i.e. horizontal gene transfer (HGT), little attentions have been paid on the ARGs carrier- ARB. In this study, we proposed the hypothesis that ARB participating in pollutant metabolism processes and becoming dominant is an important way for the enrichment of ARGs. To verify this, the antibiotic resistome and bacterial functional metabolic pathways of a sand filter was profiled using heterotrophic bacterial plate counting method (HPC), high-throughput qPCR, Illumina Hiseq sequencing and PICRUSt2 functional prediction. The results illustrated a significant leakage of ARB in the effluent of the sand filter with an average absolute abundance of approximately 102-103 CFU/mL. Further contribution analysis revealed that the dominant genera, such as Acinetobacter spp., Aeromonas spp., Elizabethkingia spp., and Bacillus spp., were primary ARGs hosts, conferring resistance to multiple antibiotics including sulfamethoxazole, tetracycline and β-lactams. Notably, these ARGs hosts were involved in nitrogen metabolism, including extracellular nitrate/nitrite transport and nitrite reduction, which are crucial in nitrification and denitrification in biofilters. For example, Acinetobacter spp., the dominant bacteria in the filter (relative abundance 69.97 %), contributed the majority of ARGs and 53.79 % of nitrite reduction function. That is, ARB can predominate by participating in the nitrogen metabolism pathways, facilitating the enrichment of ARGs. These findings provide insights into the stable presence of ARGs in biofilters from a functional metabolism perspective, offering a significant supplementary to the mechanisms of the emergence, maintenance, and transmission of BARin drinking water.
摘要：
生物滤池是饮用水中抗生素抗性基因(ARGs)和抗生素抗性细菌(ARB)的重要来源和汇。目前的研究通常从基因行为的角度将BAR在生物滤池中的流行归因于，即水平基因转移（HGT），对ARGs载体-ARB的关注很少。在这项研究中,我们提出了这样的假设，即ARB参与污染物的代谢过程并成为主导，是富集ARGs的重要途径。为了验证这一点，使用异养细菌平板计数法（HPC）对沙滤池的抗生素耐药性和细菌功能代谢途径进行了分析，高通量qPCR，IlluminaHiseq测序和PICRUSt2功能预测。结果表明，砂滤器流出物中ARB的显着泄漏，平均绝对丰度约为102-103CFU/mL。进一步的贡献分析表明，优势属，例如不动杆菌属。,气单胞菌属。,Elizabethkingiaspp.,和芽孢杆菌属。,是主要的ARGs宿主，赋予多种抗生素包括磺胺甲恶唑的耐药性，四环素和β-内酰胺。值得注意的是,这些ARGs宿主参与氮代谢，包括胞外硝酸盐/亚硝酸盐运输和亚硝酸盐还原，这对生物过滤器中的硝化和反硝化至关重要。例如,不动杆菌属。,过滤器中的优势细菌(相对丰度69.97%)，贡献了大部分ARGs和53.79%的亚硝酸盐还原功能。也就是说,ARB可以通过参与氮代谢途径而占主导地位，促进ARGs的富集。这些发现从功能代谢的角度提供了对生物过滤器中ARGs稳定存在的见解，为出现的机制提供了重要的补充，维护,以及Barin饮用水的传播。
