Potential Effects of Gut Microbiota in the Acute and Chronic Toxicity of Silver Nanoparticles to Daphnia magna

Abstract

The ecological toxicity of silver nanoparticles (AgNPs) has garnered growing concern. However, existing research primarily focuses on their acute toxicity using high doses, overlooking chronic low-dose exposure scenarios (more relevant to real environments) and the potential indirect effects mediated by gut microbiota (GM). Here, we compared the acute and chronic effects of AgNPs on Daphnia magna, examining survival, reproduction, GM alterations, and metabolic profiles. We found that acute exposure led to immediate mortality and metabolic disruptions, primarily affecting lipid and amino acid metabolism, whereas chronic exposure caused more severe reproduction failure and broader metabolic alterations, including changes in amino acids, carbohydrates, nucleic acids, energy production, and neural function. Both exposures disrupted GM composition, increasing Proteobacteria and decreasing Bacteroidetes, with chronic exposure causing more severe and lasting dysbiosis. Multiomics correlation analysis revealed that the GM plays a critical role in mediating AgNP-induced metabolic disturbances. Overall, our study highlights the differential toxicological effects of acute versus chronic AgNP exposure and underscores the importance of considering both the direct effects of nanoparticles on the host and the indirect effects mediated through the GM when assessing nanoparticle health risks. These findings provide a comprehensive understanding of AgNP toxicity and emphasize the need for integrated approaches in environmental risk assessment.