摘要

      持续暴露于低浓度的抗生素（亚最低抑制浓度：亚MIC）被认为会导致环境微生物群产生抗微生物耐药性（AMR）。然而，环境细菌群落中抗生素暴露与耐药性选择之间的关系仍然知之甚少，也未得到证实。因此，我们测量了20种抗生素的浓度、耐药性质量，并分析了从普瓦捷（法国）污水处理厂（WWTP）上游（UPS）和下游（DWS）（排放点）收集的河流生物膜中微生物的分类组成。统计分析结果表明，UPS收集的生物膜中的抗生素含量、耐药性和微生物组组成与DWS收集的有统计学差异。根据Procrustes分析，微生物群落组成和抗生素含量可能是DWS样本中抗生素耐药性基因（ARGs）组成的决定因素。然而，网络分析表明，在生物膜中测量的抗生素的出现和浓度与抗生素抗性基因和可移动遗传元件的出现和丰度无关。此外，网络分析表明，在生物膜收集的UPS中，几种ARGs和三类细菌/藻类（拟杆菌门，incertae sedis）、蓝藻/叶绿体和硝化螺旋菌）之间存在共现模式。在收集的样本中，抗生素对耐药性基因的选择没有直接影响，这表明抗生素耐药性的出现可能不仅是由于抗生素的存在，而且是一个更复杂的过程，涉及细菌群落（生物）和非生物基质之间相互作用的累积效应。然而，这项研究证实，污水处理厂是各种ARG的重要来源，需要进一步努力和立法，明确规定污水处理厂废水中抗生素和耐药性决定因素的浓度限制，以防止其在环境中的传播和持久存在。Continuous exposure to low concentrations of antibiotics (sub-minimal inhibitory concentration: sub-MIC) is thought to lead to the development of antimicrobial resistance (AMR) in the environmental microbiota. However, the relationship between antibiotic exposure and resistance selection in environmental bacterial communities is still poorly understood and unproven. Therefore, we measured the concentration of twenty antibiotics, resistome quality, and analyzed the taxonomic composition of microorganisms in river biofilms collected upstream (UPS) and downstream (DWS) (at the point of discharge) from the wastewater treatment plant (WWTP) of Poitiers (France). The results of statistical analysis showed that the antibiotic content, resistome, and microbiome composition in biofilms collected UPS were statistically different from that collected DWS. According to Procrustes analysis, microbial community composition and antibiotics content may be determinants of antibiotic resistance genes (ARGs) composition in samples collected DWS. However, network analysis showed that the occurrence and concentration of antibiotics measured in biofilms did not correlate with the occurrence and abundance of antibiotic resistance genes and mobile genetic elements. In addition, network analysis suggested patterns of co-occurrence between several ARGs and three classes of bacteria/algae: Bacteroidetes incertae sedis, Cyanobacteria/Chloroplast, and Nitrospira, in biofilm collected UPS. The absence of a direct effect of antibiotics on the selection of resistance genes in the collected samples suggests that the emergence of antibiotic resistance is probably not only due to the presence of antibiotics but is a more complex process involving the cumulative effect of the interaction between the bacterial communities (biotic) and the abiotic matrix. Nevertheless, this study confirms that WWTP is an important reservoir of various ARGs, and additional efforts and legislation with clearly defined concentration limits for antibiotics and resistance determinants in WWTP effluents are needed to prevent their spread and persistence in the environment.

https://www.frontiersin.org/articles/10.3389/fmicb.2022.795206/full