Environmental effects of nanoparticles on the ecological succession of gut microbiota across zebrafish development

The environmental stresses could significantly affect the structure and functions of microbial communities colonized in the gut ecosystem. However, little is known about how engineered nanoparticles (ENPs), which have recently become a common pollutant in the environment, affect the gut microbiota across fish development. Based on the high-throughput sequencing of the 16S rRNA gene amplicon, we explored the ecological succession of gut microbiota in zebrafish exposed to nanoparticles for three months. The nanoparticles used herein including titanium dioxide nanoparticles (nTiO₂, 100 μg/L), zinc oxide nanoparticles (nZnO, 100 μg/L), and selenium nanoparticles (nSe, 100 μg/L). Our results showed that nanoparticles exposure reduced the alpha diversity of gut microbiota at 73-90 days post-hatching (dph), but showed no significant effects at 14-36 dph. Moreover, nTiO₂ significantly (p < 0.05) altered the composition of the gut microbial communities at 73-90 dph (e.g., decreasing abundance of Cetobacterium and Vibrio). Moreover, we found that homogeneous selection was the major process (16.6-57.8%) governing the community succession of gut microbiota. Also, nanoparticles exposure caused topological alterations to microbial networks and led to increased positive interactions to destabilize the gut microbial community. This study reveals the environmental effects of nanoparticles on the ecological succession of gut microbiota across zebrafish development, which provides novel insights to understand the gut microbial responses to ENPs over the development of aquatic animals.