摘要

       据报道，生物过滤器是一种必不可少的水处理过程，是细菌抗生素抗性基因 (ARG) 的港湾。由于源水的贫营养特性，过滤生物膜在很大程度上受有机碳浓度的影响。本研究的目的是研究有机碳浓度对形成过滤生物膜中细菌抗生素抗性组的影响。我们的研究基于中试规模的砂滤器，我们使用高通量 qPCR 研究了抗生素抗性组。在三个砂滤器的15个生物膜样品中共检测到来自八类抗生素的180个抗性基因。结果表明，较高浓度的流入有机碳导致生物膜中细菌群落的多样性和抗生素抗性基因（ARGs）的丰富度较低。我们发现 ARG 的丰富度与相应的 TOC 水平之间呈负相关（p≤0.01）。此外，ARGs的绝对丰度与16S rRNA基因的丰度呈正相关（p≤0.05），并由有机碳浓度决定。具有梯度进水有机碳浓度的砂滤器导致形成不同的抗生素抗性组，典型对应分析（CCA）表明细菌群落组成的差异可能是造成这种差异的主要原因。我们还观察到 ARGs 的相对丰度有类似的趋势，随着砂滤器深度的增加而增加。然而，这种趋势在有机碳浓度低的过滤器中更为明显。总的来说，这项研究表明，有机碳浓度决定了 ARGs 的绝对丰度，也影响了饮用水砂滤器中 ARGs 的多样性和相对丰度。这些结果可能为饮用水处理中持续细菌抗生素耐药性的机制提供新的见解。

       Biofilter, an essential water treatment process, is reported to be the harbor of bacterial antibiotic resistance genes (ARGs). Due to the oligotrophic characteristic of source water, filter biofilm is largely influenced by the concentration of organic carbon. The objective of this study was to investigate the effect of organic carbon concentration on shaping bacterial antibiotic resistome in filter biofilm. Our study was based on pilot-scale sand filters, and we investigated the antibiotic resistome using high-throughput qPCR. A total of 180 resistance genes from eight categories of antibiotics were detected in 15 biofilm samples of three sand filters. The results indicated that higher concentration of influent organic carbon led to lower diversity of bacterial community and richness of antibiotic resistance genes (ARGs) in biofilm. We discovered a negative correlation (p ≤ 0.01) between the richness of ARGs and the corresponding TOC level. Moreover, the absolute abundance of ARGs was positively correlated (p ≤ 0.05) with the abundance of 16S rRNA gene and was determined by the organic carbon concentration. Sand filters with gradient influent organic carbon concentration led to the formation of different antibiotic resistomes and canonical correspondence analysis (CCA) indicated that difference in bacterial community composition was likely the main reason behind this difference. We also observed a similar trend in the relative abundance of ARGs, which increased with the depth of sand filters. However, this trend was more pronounced in filters with low organic carbon concentrations. Overall, this study revealed that the organic carbon concentration determined the absolute abundance of ARGs and also shaped the diversity and relative abundance of ARGs in drinking water sand filters. These results may provide new insights into the mechanism of persistent bacterial antibiotic resistance in drinking water treatment.

https://www.sciencedirect.com/science/article/pii/S0160412018322943