典型微塑料生物膜上病原菌的富集特征与生态风险预测

Enrichment Characteristics and Ecological Risk Prediction of Pathogens on Typical Microplastic Biofilms

微塑料作为水体环境中微生物定殖的新兴生态位可能会选择性富集病原菌,从而导致严重的生态风险和对公众健康的潜在威胁,然而不同微塑料生物膜上病原菌的富集特征及其生态风险尚不明晰.通过野外原位孵育试验,使用16S rRNA高通量测序技术探究了聚乙烯(PE)、聚丙烯(PP)、聚苯乙烯(PS)、聚对苯二甲酸乙二醇酯(PET)和聚氯乙烯(PVC)这5种典型微塑料生物膜上细菌群落结构的差异、人类病原菌的赋存特征以及生态风险的预测.结果显示,经过28 d原位孵育后所有微塑料表面均形成了明显的生物膜,并且所有微塑料生物膜上细菌群落的多样性和丰富度均高于周围水体,表明微塑料对周围水体中的微生物具有显著的富集作用.每种类型微塑料生物膜上均形成了独特的细菌群落结构,特别是PVC更倾向于选择性富集变形菌门(Proteobacteria)的细菌.使用HPB数据库共注释出47种人类病原菌,有6种被识别为Ⅰ类重点控制的抗生素耐药性病原菌.微塑料生物膜上人类病原菌的检出种类和相对丰度均高于周围水体,巴尔通氏体(Bartonella)、伯克霍尔德氏菌属(Burkholderia)和布鲁氏菌属(Brucella)等优势病原菌均选择性富集在微塑料生物膜上.基于BugBase的微生物功能表型预测结果显示,微塑料生物膜上生物膜形成、移动元件和潜在致病性3种功能表型的占比分别增加了2.38%~5.57%、0.82%~7.13%和3.04%~8.30%,主要是由属于α-变形菌纲(α-Proteobacteria)和γ-变形菌纲(γ-Proteobacteria)的细菌贡献.研究结果不仅揭示了微塑料生物膜上选择性富集的机会性病原菌可能会导致水体环境中致病性和抗生素耐药性传播风险的加剧,也为正确评估水体环境中微塑料污染带来的生态风险提供参考依据.

As an emerging niche colonized by microorganisms,microplastics may selectively enrich pathogens,resulting in crucial ecological risks and potential threats to public health in aquatic environments.However,the enrichment characteristics and ecological risks of pathogens on different microplastic biofilms remain unclear.In this study,16S rRNA high-throughput sequencing technology was used to investigate the differences in the bacterial community structure,occurrence characteristics of pathogens,and prediction of ecological risks on five typical microplastic biofilms of polyethylene(PE),polypropylene(PP),polystyrene(PS),polyethylene terephthalate(PET),and polyvinyl chloride(PVC)through a field in-situ incubation experiment.The results showed that after 28 d of in situ incubation,the macroscopic biofilms were formed on the surface of all microplastics,and the diversity and richness of the bacterial community on all microplastic biofilms were higher than in the surrounding water,indicating that the microorganisms in the surrounding water were selectively enriched on microplastics.Each type of microplastic biofilm had formed a unique bacterial community structure;in particular,PVC microplastics were more inclined to selectively enrich the members of Proteobacteria.A total of 47 human pathogens were identified using the HPB database,including six antibiotic resistance pathogens belonging to the lists of critical priority control.The number and total abundance of human pathogens detected on microplastic biofilm were higher than those in the surrounding water,and the dominant pathogens such as Bartonella,Burkholderia,and Brucella were selectively enriched on microplastic biofilms.Microbial phenotype prediction results based on BugBase showed that three functional phenotypes including biofilm formation,mobile element contained,and potentially pathogenic on microplastic biofilms had significantly increased by 2.38%-5.57%,0.82%-7.13%,and 3.04%-8.30%,respectively,which were mainly contributed by α-Proteobacteria and γ-Proteobacteria.These results not only indicate that the selective enrichment of opportunistic pathogens on microplastic biofilms may lead to the increased risk of pathogenicity and antibiotic resistance co-spread but also provide reference for the accurate assessment of ecological risks caused by microplastic pollution in aquatic environments.