摘要

       越来越多的化学物质可以渗透细菌细胞，促进水平基因转移（HGT），从而促进抗生素耐药基因（ARGs）在环境中的传播。以往的研究表明，1-丁基-3-甲基咪唑六氟磷酸（[BMIm][PF6]）是一种离子液体，可促进细菌间某些arg的HGT。然而，在不同的环境中，更广泛的ARGs和相关的移动遗传元素（mge）的动态响应是未知的。在这里，我们使用宏基因组工具研究了暴露于[BMIm][PF6]的沉积物和淡水微宇宙中的抗性和微生物组的变化。暴露于0.1或1.0g/L的16h显著富集了207个主要编码淡水微宇宙中的外排泵的ARG亚型，以及可培养的抗生素抗性细菌。这种抗性的增加归因于MGEs促进的HGT（428个质粒、61个整合子整合酶基因和45个基因盒被富集）以及HGT相关功能基因。有趣的是，在[BMIm][PF6]暴露后（16h内）细菌群落结构发生显著变化之前，耐药性快速增加。在暴露于[BMIm][PF6]28d的沉积物微观结构中也出现了类似的ARG富集现象，这种长时间的暴露影响了微生物群落结构（例如，蛋白质细菌丰度显著增加）。总的来说，本研究表明[BMIm][PF6]的释放可以通过增加HGT和偶然选择外排泵基因来迅速丰富接收环境中的抗生素抗性，从而促进ARG的繁殖。

         An expanding list of chemicals may permeabilize bacterial cells and facilitate horizontal gene transfer (HGT), which enhances propagation of antibiotic resistance genes (ARGs) in the environment. Previous studies showed that 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF6]), an ionic liquid, can facilitate HGT of some ARGs among bacteria. However, the dynamic response of a wider range of ARGs and associated mobile genetic elements (MGEs) in different environments is unknown. Here, we used metagenomic tools to study shifts of the resistome and microbiome in both sediments and freshwater microcosms exposed to [BMIm][PF6]. Exposure for 16 h to 0.1 or 1.0 g/L significantly enriched more than 207 ARG subtypes primarily encoding efflux pumps in freshwater microcosms as well as cultivable antibiotic-resistant bacteria. This resistome enrichment was attributed to HGT facilitated by MGEs (428 plasmids, 61 integron-integrase genes, and 45 gene cassettes were enriched) as well as to HGT-related functional genes. Interestingly, resistome enrichment occurred fast (within 16 h) after [BMIm][PF6] exposure, before any significant changes in bacterial community structure. Similar ARG enrichment occurred in sediment microcosms exposed to [BMIm][PF6] for 28 d, and this longer exposure affected the microbial community structure (e.g., Proteobacteria abundance increased significantly). Overall, this study suggests that [BMIm][PF6] releases could rapidly enrich the antibiotic resistome in receiving environments by increasing HGT and fortuitously selecting for efflux pump genes, thus contributing to ARG propagation.

         https://pubs.acs.org/doi/abs/10.1021/acs.est.9b04116