摘要

       城市河流生物膜是潜在的耐药和耐药基因研究热点。携带抗性基因的生物膜群落可能受到城市排水（即污水处理厂废水和雨水径流）中污染物输入（如金属和抗生素）的影响；需要了解这些群落的生态学及其抗性。鉴于ARGs与金属抗性基因（MRGs）共现的潜在重要性，我们研究了三种ARGs（四环素[tetW]和磺胺类[sulI和sulII]）、四种MRGs（铅[pbrT]、铜[copA]，以及镉/钴/锌[czcA和czcC]），通过定量PCR和生物膜细菌群落组成，通过MiSeq 16S测序，在河流流域的城市化梯度（即发达地区、农业和森林地区）的四个时间点进行。结果表明，ARG和MRG的丰度受土地利用时间交互作用的显著影响，在一年中的特定时间内，更多的城市地区出现了更大的抗性丰度。还观察到，ARG和MRG剖面的变化受不同土地利用类型的群落组成差异的影响，这些差异是对次级流域土地利用驱动的河流理化参数（pH、氧化还原、温度、养分有效性和金属浓度）变化的响应。此外，这些群落中ARGs和MRGs之间的动态关系也呈强正相关。综上所述，我们的研究结果表明，人类活动引起的环境特性变化可能通过调节生物膜群落的时间和空间结构来驱动生物膜群落的ARG-MRG谱。

       Urban stream biofilms are potential hotspots for resistomes and antibiotic resistance genes (ARGs). Biofilm communities that harbor resistance genes may be influenced by contaminant input (e.g., metals and antibiotics) from urban drainage (i.e., Wastewater Treatment Plant effluent and stormwater runoff); understanding the ecology of these communities and their resistome is needed. Given the potential importance of the co-occurrence of ARGs and metal resistance genes (MRGs), we investigated the spatial and temporal distribution of three ARGs (tetracycline [tetW] and sulfonamides [sulI and sulII]), four MRGs (lead [pbrT], copper [copA], and cadmium/cobalt/zinc [czcA and czcC]) via quantitative PCR and biofilm bacterial community composition via MiSeq 16S sequencing at four time points along an urbanization gradient (i.e., developed, agriculture, and forested sites) in a stream's watershed. Our results revealed that ARG and MRG abundances were significantly affected by land use-time interaction, with greater resistance abundances occurring in more urban locations during particular times of the year. It was also observed that changes in ARG and MRG profiles were influenced by differences in community composition among land use types, and that these differences were in response to changes in stream physicochemical parameters (pH, redox, temperature, nutrient availability, and metal concentration) that were driven by sub-watershed land use. Moreover, the dynamics between ARGs and MRGs within these communities correlated strongly and positively with one another. Taken altogether, our results demonstrate that changes in environmental properties due to human activity may drive the ARG-MRG profiles of biofilm communities by modulating community structure over time and space.