Gut microbiota and metabolic health risks from chronic low-dose microplastic exposure with focus on Desulfovibrio spp.

Humans inevitably ingest microplastics (MPs) through respiration and diet, yet the long-term effects of routine low-dose intake on the gut microbiota remain unclear. This study investigated the long-term impact of polystyrene microplastics (PS-MPs) on the gut microbiota and metabolism in mice at both low and high dosages. Male BALB/c mice were exposed to PS-MPs at concentrations of 0 (control: regular water), 10 (low-dose) and 100 µg mL^-1 (high-dose) for six-week experiment. Body weight, colon length, gut microbiota composition, and serum metabolites were assessed. Results indicated that long-term low-dose PS-MP intake significantly altered colon length and increased the abundance of Lepagella and Desulfovibrio spp., which are associated with colorectal cancer and gastrointestinal inflammatory diseases. Metabolomic analysis revealed significant impacts of PS-MP on lipid and amino acid metabolism in mice, activating metabolic pathways linked to cancer and neurological diseases. Notably, the upregulated abundance of Desulfovibrio spp. was significantly positively correlated with several risk metabolites (e.g., L-Glutamic gamma-semialdehyde, 8-Amino-7-oxonanoic acid, and Cer(d18:0/16:0)), which are closely related to the development of neurological disorders, metabolic diseases, and cancer. Moreover, PS-MP exposure promoted the conjugation of mobile antibiotic resistance genes and the formation of biofilms by opportunistic pathogens, potentially exacerbating microbial resistance and posing a public health threat. While this study systematically evaluated the longitudinal effects of PS-MPs on gut microbiota and metabolic profiles, further research is needed to clarify the specific molecular mechanisms. Overall, this study reveals the multifaceted impacts of microplastic exposure on host metabolism and health, underscoring the importance of assessing microplastic health risks and developing preventive measures.