Study on the association between microplastic exposure and gut microbiota based on metagenomics: A pilot study on 66 young college students in China

OBJECTIVE: This study aimed to evaluate the types and mass concentrations of microplastics found in the stools of young college students. The underlying connections between microplastic exposure and gut microbiota were revealed. METHODS: The study involved 66 participants, from whom stool samples were collected. Pyrolysis gas chromatography/mass spectrometry (Py-GCMS) was used to identify the types and mass concentrations of microplastics. Metagenomic sequencing was performed on the gut microbiota using high-throughput sequencing and metagenomic analysis techniques. Participants were divided into low group (LG) and high group (HG) based on the median mass concentration of microplastics in their stools. The differences in microbial diversity and species with significant differences between the two groups were analyzed. Spearman's correlation analysis was conducted to assess the associations between microbial characteristics and gene functions. RESULTS: The detection rate of microplastics in the stool samples was 98.5 %, with a median mass concentration of 54.7 μg/g. Significant differences were observed in gut microbiota between the two groups in terms of alpha and beta diversities. The relative abundance of Segatella copri was higher in the LG, while the relative abundance of Escherichia coli was higher in the HG. Compared with the LG, the gut microbiota in the HG exhibited an increase in the relative abundance of harmful bacteria, such as Dialister invisus, Clostridium fessum, and Evtepia gabavorous. The ADONIS analysis revealed that PS microplastics had a significant impact on the structure of the gut microbiota. However, no significant differences were observed among the metabolic pathways annotated in the Kyoto Encyclopedia of Genes and Genomes database between the two groups at either level I or II. CONCLUSION: Participants with higher mass concentrations of microplastics in their stools exhibited an increase in the abundance of harmful intestinal bacteria. PS microplastics had the most profound impact on the gut microbiota structure.