Microbial ecology of microplastic biofilm in fresh- and wastewater

"Microplastics are emerging contaminants of concern in the freshwater environment due to their ecotoxicity to aquatic organisms. A secondary concern related to microplastic pollution is that these particles may serve as carriers of microbial communities from source waters into receiving waters. A limited number of field studies have raised alarm that the biofilm communities on microplastics in the fresh and marine water environment may possess pathogens, perhaps due to by-pass of disinfection processes for wastewater derived microplastics. Here, we were interested in understanding the role of source water quality, polymer type, and microplastic particle size on the resulting biofilm microbial communities. A controlled laboratory was performed to investigate the microbial communities observed in bulk water compared to those in the microplastic biofilm via high throughput sequencing. The biofilm community varied as a function of source water and polymer type, but not particle size. The biofilm microbial communities differed from the bulk water communities but using qPCR, they did not have a higher prevalence of indicator organisms based (BacHum gene copies / 16S rRNA gene copies). These data can help us better understand microprticle biofilms in different water environments."由于微塑料对水生生物具有生态毒性，其已成为淡水环境中备受关注的新兴污染物。与微塑料污染相关的另一项隐患在于，这些颗粒可作为微生物群落的载体，将其从源头水体输送至受纳水体。目前已有少量实地研究敲响警钟，指出淡水与海水环境中微塑料表面的生物膜群落可能携带病原体，这或许与源自废水的微塑料未经过消毒工艺处理有关。本研究旨在探究源头水体水质、聚合物类型以及微塑料粒径对最终形成的生物膜微生物群落的影响。通过开展控制变量室内实验，采用高通量测序技术对比分析主体水体与微塑料生物膜中的微生物群落结构。研究发现，生物膜群落组成随源头水体水质与聚合物类型发生变化，但不受微塑料粒径影响。尽管生物膜微生物群落与主体水体微生物群落存在显著差异，但通过实时定量PCR（qPCR）分析可知，其指示生物的相对丰度并未更高（以BacHum基因拷贝数与16S rRNA基因拷贝数的比值为衡量标准）。本研究数据有助于更深入地认识不同水环境中的微塑料生物膜特性。