Plastic pollution in aquatic environments, particularly microplastics (<5 mm), is an emerging health threat. The buoyancy, hydrophobic hard surfaces, novel polymer carbon sources and long-distance transport make microplastics a unique substrate for biofilms, potentially harbouring pathogens and enabling antimicrobial resistance (AMR) gene exchange. Microplastic concentrations, their polymer types and the associated microbial communities were determined in paired, contemporaneous samples from the Dutch portion of the river Rhine. Microplastics were collected through a cascade of 500/100/10 μm sieves; filtrates and surface water were also analysed. Microplastics were characterized with infrared spectroscopy. Microbial communities and selected virulence and AMR genes were determined with 16S rRNA-sequencing and qPCR. Average microplastic concentration was 213,147 particles/m³; polyamide and polyvinylchloride were the most abundant polymers. Microbial composition on 100–500 μm samples differed significantly from surface water and 10–100 μm or smaller samples, with lower microbial diversity compared to surface water. An increasingly ‘water-like’ microbial community was observed as particles became smaller. Associations amongst specific microbial taxa, polymer types and particle sizes, as well as seasonal and methodological effects, were also observed. Known biofilm-forming and plastic-degrading taxa (e.g. Pseudomonas) and taxa harbouring potential pathogens (Pseudomonas, Acinetobacter, Arcobacter) were enriched in certain sample types, and other risk-conferring signatures like the sul1 and erm(B) AMR genes were almost ubiquitous. Results were generally compatible with the existence of taxon-selecting mechanisms and reduced microbial diversity in the biofilms of plastic substrates, varying over seasons, polymer types and particle sizes. This study provided updated field data and insights on microplastic pollution in a major riverine environment.

水生环境中的塑料污染，尤其是微塑料（<5毫米），正在成为一种新兴的健康威胁。浮力，疏水性硬质表面，新颖的聚合物碳源和长距离运输使微塑料成为生物膜的独特基质，潜在地藏有病原体并实现了抗微生物剂（AMR）基因交换。在成对的同时期莱茵河荷兰部分样品中测定了微生物的浓度，其聚合物类型和相关的微生物群落。通过级联的500/100/10μm筛网收集微塑料；还分析了滤液和地表水。用红外光谱对微塑料进行了表征。通过16S rRNA测序和qPCR确定了微生物群落，选定的毒力和AMR基因。³；聚酰胺和聚氯乙烯是最丰富的聚合物。100–500μm样品中的微生物组成与地表水和10–100μm或更小的样品有显着差异，与地表水相比，微生物多样性较低。随着颗粒变小，观察到越来越多的“水样”微生物群落。还观察到了特定微生物分类群，聚合物类型和粒径以及季节和方法学影响之间的关联。某些样品类型中富含已知的生物膜形成和可塑性降解的分类单元（例如假单胞菌）和带有潜在病原体（假单胞菌，不动杆菌，变形杆菌）的分类单元，以及其他具有风险风险的特征，如sul1和erm（B）AMR基因几乎无处不在。结果通常与分类单元选择机制的存在和塑料基质生物膜中微生物多样性的减少（与季节，聚合物类型和粒径不同）相吻合。这项研究提供了有关主要河流环境中微塑性污染的最新现场数据和见解。