摘要
      全氟辛酸（PFOA）是一类永久性有机污染物，经常在地表水和地下水中检测到，后者主要由含有微生物群落的多孔介质（如土壤、沉积物和含水层）组成。因此，我们研究了全氟辛烷磺酸对水生态系统的影响，发现在2.4μM全氟辛烷酸的刺激下，反硝化菌由于其宿主抗生素抗性基因（ARGs）而显著富集，其丰度是对照的1.45倍。此外，Fe（II）电子供体促进了反硝化代谢。具体而言，2.4μM全氟辛烷磺酸显著提高了总无机氮的去除率178.6%。微生物群落以反硝化细菌为主（丰度为67.8%）。值得注意的是，硝酸盐还原亚铁氧化（NRFO）细菌脱氯单胞菌、酸杆菌、慢生根瘤菌等显著富集。全氟辛烷磺酸驱动反硝化菌富集的选择压力是两倍。首先，毒性全氟辛烷磺酸诱导反硝化细菌产生ARGs，主要包括外排型（占55.4%）和抗生素失活型（占41.2%），提高了微生物对全氟辛烷酸的耐受性。随着可水平传播的ARGs总数增加47.1%，ARGs水平传播的风险增加。其次，Fe（II）电子通过通道蛋白-细胞色素c细胞外电子转移系统（EET）传输，促进硝酸还原酶的表达，进而进一步增强反硝化作用。总之，全氟辛烷磺酸调节了微生物群落结构，影响了微生物TN的去除功能，并增加了反硝化宿主对ARGs的贡献，但全氟辛烷酸诱导的ARGs产生可能会造成严重的生态威胁，需要全面研究。
Abstract
Perfluorooctanoic acid (PFOA), a class of permanent organic pollutants, is frequently detected in surface and ground water, with the latter made up primarily of porous media (such as soils, sediments, and aquifers) that harbor microbial communities. Therefore, we investigated the effects of PFOA on water ecosystems and found that, under stimulation by 2.4 μM PFOA, denitrifiers were significantly enriched due to their hosting antibiotic resistant genes (ARGs), which were 1.45 times more abundant than the control. Furthermore, denitrifying metabolism was enhanced by Fe(II) electron donation. Specifically, 2.4 μM PFOA significantly enhanced the removal of total inorganic nitrogen by 178.6%. The microbial community became predominated by denitrifying bacteria (67.8% abundance). Notably, the nitrate-reduction ferrous-oxidizing (NRFO) bacteria Dechloromonas, Acidovorax, Bradyrhizorium, etc. were significantly enriched. The selective pressures of PFOA driving the enrichment of denitrifiers were twofold. First, the toxic PFOA induced denitrifying bacteria to produce ARGs, mainly including the efflux (occupying 55.4%) and antibiotic inactivation (occupying 41.2%) types, which improved microbial tolerance to PFOA. The risk of horizontal ARGs transmission was elevated as the overall number of horizontally transmissible ARGs increased by 47.1%. Second, Fe(II) electrons were transported via the porin-cytochrome c extracellular electrons transfer system (EET), promoting the expression of nitrate reductases, which in turn further enhanced denitrification. In summary, PFOA regulated the microbial community structure and influenced microbial TN removal functions and increased the contribution of ARGs by the denitrifier hosts, but the PFOA-induced production of ARGs may pose a serious ecological threat that needs to be comprehensively investigated.

https://www.sciencedirect.com/science/article/abs/pii/S0043135423002488