摘要

      利用生物膜去除废水中有机物或营养物质的附着生长生物过程被认为含有抗生素抗性基因（ARGs）。这些过程中的生物膜在空间上是不均匀的，但是对于复杂的混合培养生物膜中ARGs的深度分层却知之甚少。为了解决这一知识空白，我们采用冷冻切片和定量聚合酶链反应相结合的实验方法，对实验室规模的旋转环形反应器中的生物膜中三种ARGs（sul1、ermB和qnrS）和1类整合子整合酶基因intI1的空间分布进行了定量研究。我们还利用高通量16S核糖体RNA（rRNA）基因测序来表征生物膜中的群落结构。ARG-sul1和integron-integrase基因intI1在靠近流体-生物膜界面的上层生物膜中的丰度高于下层生物膜，且与下层生物膜的距离和基因丰度呈显著相关。ermB和qnrS基因相对丰度较低。微生物群落结构随采样日期和距下卧层的距离变化显著。这些发现突出了废水处理生物膜中与底层之间距离的遗传和分类异质性，并表明sul1和intI1在流体生物膜界面附近特别丰富，其中细胞最有可能分离并流入处理系统的下游部分，并最终释放到通过废水进行环境保护。

       Attached growth bioprocesses that use biofilms to remove organic matter or nutrients from wastewater are known to harbor antibiotic resistance genes (ARGs). Biofilms in these processes are spatially heterogeneous, but little is known about depth stratification of ARGs in complex, mixed culture biofilms. To address this knowledge gap, we used an experimental approach combining cryosectioning and quantitative polymerase chain reaction to quantify the spatial distribution of three ARGs (sul1, ermB, and qnrS) and the class 1 integron-integrase gene intI1 in biofilms from a lab-scale rotating annular reactor fed with synthetic wastewater. We also used high throughput 16S ribosomal RNA (rRNA) gene sequencing to characterize community structure with depth in biofilms. The ARG sul1 and the integron-integrase gene intI1 were found in higher abundances in upper layers of biofilm near the fluid-biofilm interface than in lower layers and exhibited significant correlations between the distance from substratum and gene abundances. The genes ermB and qnrS were present in comparatively low relative abundances. Microbial community structure varied significantly by date of sampling and distance from the substratum. These findings highlight the genetic and taxonomic heterogeneity with distance from substratum in wastewater treatment biofilms and show that sul1 and intI1 are particularly abundant near fluid-biofilm interfaces where cells are most likely to detach and flow into downstream portions of treatment systems and can ultimately be released into the environment through effluent.

        https://onlinelibrary.wiley.com/doi/abs/10.1002/bit.26887