Suspended activated sludge (AS) and carrier-attached biofilms simultaneously exist in an integrated fixed film activated sludge (IFAS) system. However, the differentiation of antibiotic resistance genes (ARGs) and microbial communities in different types of biofilms is rarely reported. In this study, successions of ARGs and microbial communities of AS and two types of suspended carrier-attached biofilms over seasons were investigated in the IFAS system of one municipal wastewater treatment plant. Results showed that substantial differences were found in the distribution pattern of ARGs, bacterial communities, and predicted microbial function between AS and attached biofilms. The relative abundances of all detected ARGs in AS were significantly higher than those in attached biofilms. ARGs with higher relative abundances generally existed in K3 carrier (surface area ≥ 800 m²/m³) attached biofilms than those in K1 carrier (surface area ≥ 450 m²/m³) biofilms. The relative abundances of ARGs were negatively correlated with temperature and biochemical oxygen demand (BOD₅) and positively correlated with ammonium nitrogen contents for AS but not for attached biofilms. No significant relationship was found between the extracellular polymeric substance (EPS) content and ARG abundance for all samples. Temperature, BOD₅, and ammonium nitrogen contents were closely connected to microbial communities. The Bray–Curtis distance of bacterial communities between two adjacent sampling seasons for AS was larger than those of two attached biofilms. Network analysis indicated that the AS network had more positive links and intense connections than the attached biofilm networks, potentially facilitating the dissemination of ARGs. The differential distribution of ARGs among the three types of samples was significantly correlated with the microbial co-occurrence network topological properties. Bray–Curtis distance and network analysis suggest that microbial community is more robust in attached biofilms than in suspended AS. This work provides a more in-depth understanding of ARGs and microbial community distributions in wastewater biofilms.

悬浮的活性污泥（AS）和附有载体的生物膜同时存在于集成的固定膜活性污泥（IFAS）系统中。然而，很少有人报道不同类型生物膜中抗生素抗性基因（ARGs）和微生物群落的分化。在这项研究中，在一个市政废水处理厂的IFAS系统中，调查了不同季节的AS的ARGs和AS微生物群落以及两种类型的悬浮在载体上的悬浮生物膜的连续性。结果表明，AS和附着的生物膜之间的ARGs分布模式，细菌群落以及预测的微生物功能之间存在实质性差异。AS中所有检测到的ARG的相对丰度均显着高于附着的生物膜中的相对丰度。² / m ³）附着的生物膜要比K1载体（表面积≥450 m ² / m ³）生物膜中的附着。ARGs的相对丰度与温度和生化需氧量（BOD ₅）呈负相关，与AS而不是附着的生物膜上的铵态氮含量呈正相关。在所有样品的细胞外聚合物（EPS）含量和ARG丰度之间均未发现显着关系。温度，生化需氧量₅，铵态氮含量与微生物群落紧密相关。AS的两个相邻采样季节之间细菌群落的Bray-Curtis距离大于两个附着的生物膜的细菌距离。网络分析表明，与附属的生物膜网络相比，AS网络具有更积极的联系和更紧密的联系，从而有可能促进ARG的传播。三种类型样品中ARGs的差异分布与微生物共生网络的拓扑特性显着相关。Bray-Curtis距离和网络分析表明，附着生物膜中的微生物群落比悬浮AS中的微生物群落更强健。这项工作提供了对废水生物膜中的ARGs和微生物群落分布的更深入的了解。