Plastisphere-Derived Extracellular Vesicles: Hotspots for Antibiotic Resistance Genes and Virulence Factor Genes

Extracellular vesicles (EVs) are produced by a wide range of microorganisms, serving as a unique reservoir and transporter for antibiotic resistance genes (ARGs) and virulence factor genes (VFGs). While the plastisphere is recognized as a hotspot for ARGs and potential pathogens, it remains unclear whether pathogenic bacteria in the plastisphere release ARGs and VFGs within EVs, with potential to amplify health risks. We investigated the presence of ARGs and VFGs within EVs and their microbial origins in the plastisphere via a long-term controlled microcosm experiment. Our results reveal that the abundance of EVs in the plastisphere can reach up to 1011/m2. Various ARGs and mobile genetic elements (MGEs) were detected in plastisphere-derived EVs, showing a hierarchical enrichment along the environment-plastisphere-EVs pathway. These EVs-releasing microbes in the plastisphere have been found in plastic samples across the globe. Some potential pathogens associated with EVs were enriched in the plastisphere and displayed a strong correlation with VFGs. Additionally, we observed that heavy metal pollution significantly enhances the presence of ARGs in plastisphere-derived EVs. Interestingly, when exposed to heavy metal stress, EVs derived from plastispheres incubated in soil and water showed distinct alterations in ARGs driven by different underlying mechanisms. Our findings shed light on the prevalence of ARGs, and the pathogenic characteristics of EVs in the plastisphere, highlighting the potential dissemination of ARGs and pathogenicity through plastisphere EVs.

细胞外囊泡（Extracellular vesicles, EVs）可由多种微生物产生，是抗生素抗性基因（antibiotic resistance genes, ARGs）与毒力因子基因（virulence factor genes, VFGs）的独特储存库与转运载体。尽管塑料圈（plastisphere）被公认为抗生素抗性基因与潜在病原体的热点生境，目前仍不清楚塑料圈中的致病菌是否会通过细胞外囊泡释放抗生素抗性基因与毒力因子基因，进而存在放大健康风险的可能性。本研究通过长期受控微宇宙实验，探究了塑料圈中细胞外囊泡内抗生素抗性基因与毒力因子基因的存在情况及其微生物来源。研究结果显示，塑料圈中细胞外囊泡的丰度最高可达10¹¹/平方米。从塑料圈分离得到的细胞外囊泡中检测到多种抗生素抗性基因与可移动遗传元件（mobile genetic elements, MGEs），并呈现出"环境-塑料圈-细胞外囊泡"这一通路的层级富集特征。这类可释放细胞外囊泡的塑料圈微生物，已在全球范围内的塑料样本中被检出。部分与细胞外囊泡相关的潜在致病菌在塑料圈中富集，且与毒力因子基因呈现显著相关性。此外，本研究观察到重金属污染可显著提升塑料源细胞外囊泡中抗生素抗性基因的丰度。值得注意的是，当暴露于重金属胁迫时，土壤与水体中培育的塑料圈来源细胞外囊泡，其携带的抗生素抗性基因会因不同的潜在调控机制发生显著差异变化。本研究结果阐明了塑料圈中抗生素抗性基因的流行情况与细胞外囊泡的致病特征，凸显了通过塑料圈细胞外囊泡传播抗生素抗性基因与致病原的潜在风险。