生物膜对于饮用水管道中抗生素抗性基因(ARGs)的传播很重要。本研究使用宏基因组和代谢组学分析研究了氯消毒和氨氮对管道生物膜中ARG的影响。氯消毒降低了未分类的_c_放线菌的相对丰度,酸性微生物,和Candidatus_Pelagibacter到394-430TPM,114-123TPM,和49-54TPM,分别。相应地,ARGsSaur_rpoC_DAP,macB,MFD降低到8-12TPM,81-92TPM和30-35TPM,分别。代谢组学的结果表明,氯消毒抑制了ABC转运体的途径,脂肪酸生物合成,不饱和脂肪酸的生物合成,和氨基酸的生物合成。这些途径与细胞膜完整性和胞外聚合物(EPS)分泌有关。氯消毒诱导EPS相关基因减少,导致细菌群落的相对丰度和抗生素抗性较低。然而,添加约0.5mg/L的NH3-N诱导这些代谢途径的上调。此外,NH3-N的添加显著增加了与无机和有机氮代谢途径相关的酶的相对丰度,如氨单加氧酶,谷氨酰胺合成酶,和谷氨酸合成酶.由于EPS的保护和氮代谢,主要细菌属和相关ARGs的相对丰度增加到与没有消毒的管道生物膜相同的水平。因此,NH3-N降低了氯消毒的ARGs去除效率。有必要采取措施提高NH3-N和ARGs的去除率,以防止其在饮用水中的风险。
The biofilm is important for the antibiotic resistance genes (ARGs) propagation in drinking water pipelines. This study investigated the influence of chlorine disinfection and ammonia nitrogen on the ARGs in pipelines biofilm using metagenomic and metabolomics analysis. Chlorine disinfection reduced the relative abundance of unclassified_c_Actinobacteria, Acidimicrobium, and Candidatus_Pelagibacter to 394-430 TPM, 114-123 TPM, and 49-54 TPM, respectively. Correspondingly, the ARGs Saur_rpoC_DAP, macB, and mfd was reduced to 8-12 TPM, 81-92 TPM and 30-35 TPM, respectively. The results of metabolomics suggested that chlorine disinfection suppressed the pathways of ABC transporters, fatty acid biosynthesis, biosynthesis of unsaturated fatty acids, and biosynthesis of amino acids. These pathways were related to the cell membrane integrality and extracellular polymeric substances (EPS) secretion. Chlorine disinfection induced the decrease of EPS-related genes, resulting in the lower relative abundance of bacterial community and their antibiotic resistance. However, added approximately 0.5 mg/L NH3-N induced up-regulation of these metabolic pathways. In addition, NH3-N addition increased the relative abundance of enzymes related to inorganic and organic nitrogen metabolic pathway significantly, such as ammonia monooxygenase, glutamine synthetase, and glutamate synthase. Due to the EPS protection and nitrogen metabolism, the relative abundance of the main bacterial genera and the related ARGs increased to the level equal to that in pipelines biofilm with no disinfection. Therefore, NH3-N reduced the ARGs removal efficiency of chlorine disinfection. It is necessary to take measures to improve the removal rate of NH3-N and ARGs for preventing their risks in drinking water.