摘要
      与回收废水相关的生物膜由不同种类的微生物群落组成，这些微生物群落持续暴露于抗生素残留物中。抗生素耐药性细菌（ARB）及其相关抗生素耐药性基因（ARGs）的存在也确保了生物膜的持续选择压力，生物膜可以被视为抗生素耐药性传播的热点，但也可以在抗生素降解中发挥作用。在本研究中，在六种抗生素暴露（10µg L−1）开始和2周后收集的再生废水和生物膜样品中，跟踪了抗生素降解和四种ARG（qnrS、sul1、blaTEM、ermB）以及两种可移动遗传元件（MGE）（包括IS613和intl1）的丰度。抗生素被部分降解，并保持在文献中描述的环境样品的最低最低抑制浓度（MIC）以上。在生物膜和再生废水中检测到的最丰富的基因是sul1、ermB和intl1。在暴露的2周内，生物膜中这些基因的相对丰度增加，但在对照样品中发现了最高值（没有抗生素压力），这表明细菌群落组成和多样性是生物膜中耐药性选择和繁殖的驱动力，而不是暴露于抗生素。对浮游生物和生物膜细菌群落进行了表征。浮游生物细胞被经典地定义为“悬浮液中自由流动的细菌”，而不是固着状态（所谓的生物膜）：Costerton等人（1999）所说的“封闭在自产聚合物基质中并粘附在惰性或活表面上的细菌细胞的结构化群落”。
在含有抗生素的回收废水中，一些已知携带ARG的属，如链球菌属、Exigobacterium属、无色原体属、甲基藻科和卟啉单藻科的丰度增加。生物膜的存在降低了废水中这些属的水平，但相反，生物膜也可以作为这些细菌的蓄水池，使低多样性废水重新定植。似乎保持高度多样性对于限制浮游细菌中抗微生物耐药性的传播很重要。抗生素对光学相干断层扫描（OCT）监测的生物膜发育没有影响。需要进一步研究，以阐明生物膜中物种间交流对抗生素降解、耐药性发展和传播的作用。
Abstract
Reclaimed wastewater associated biofilms are made up from diverse class of microbial communities that are continuously exposed to antibiotic residues. The presence of antibiotic resistance bacteria (ARB) and their associated antibiotic resistance genes (ARGs) ensures also a continuous selection pressure on biofilms that could be seen as hotspots for antibiotic resistance dissemination but can also play a role in antibiotic degradation. In this study, the antibiotic degradation and the abundance of four ARGs (qnrS, sul1, blaTEM, ermB), and two mobile genetic elements (MGEs) including IS613 and intl1, were followed in reclaimed wastewater and biofilm samples collected at the beginning and after 2 weeks of six antibiotics exposure (10 µg L−1). Antibiotics were partially degraded and remained above lowest minimum inhibitory concentration (MIC) for environmental samples described in the literature. The most abundant genes detected both in biofilms and reclaimed wastewater were sul1, ermB, and intl1. The relative abundance of these genes in biofilms increased during the 2 weeks of exposure but the highest values were found in control samples (without antibiotics pressure), suggesting that bacterial community composition and diversity are the driven forces for resistance selection and propagation in biofilms, rather than exposure to antibiotics. Planktonic and biofilm bacterial communities were characterized. Planktonic cells are classically defined “as free flowing bacteria in suspension” as opposed to the sessile state (the so-called biofilm): “a structured community of bacterial cells enclosed in a self-produced polymeric matrix and adherent to an inert or living. surface” as stated by Costerton et al. (1999).

The abundance of some genera known to harbor ARG such as Streptococcus, Exiguobacterium, Acholeplasma, Methylophylaceae and Porphyromonadaceae increased in reclaimed wastewater containing antibiotics. The presence of biofilm lowered the level of these genera in wastewater but, at the opposite, could also serve as a reservoir of these bacteria to re-colonize low-diversity wastewater. It seems that maintaining a high diversity is important to limit the dissemination of antimicrobial resistance among planktonic bacteria. Antibiotics had no influence on the biofilm development monitored with optical coherence tomography (OCT). Further research is needed in order to clarify the role of inter-species communication in biofilm on antibiotic degradation and resistance development and spreading.

https://www.sciencedirect.com/science/article/abs/pii/S0043135422007795