Evaluation of the gut microbiome alterations in healthy rats after dietary exposure to different synthetic ZnO nanoparticles

Aims Although synthetic ZnO nanoparticles (Nano-ZnO) as an alternative of ZnO compounds have been extensively used such as in livestock production, the increased consuming of Nano-ZnO has raised considerable concerns in environmental pollution and public health. Because of the low digestion of Nano-ZnO, the systematic studies on their interactions with gut microbiota remain to be clarified. Materials and methods Nano-ZnOs were prepared by co-precipitation (ZnO-cp) and high temperature thermal decomposition (ZnO-td) as well as the commercial type (ZnO-s). Transmission electron microscopy (TEM) was used to monitor the morphology of Nano-ZnO. CCK-8 assay was used for cytotoxicity evaluation. Total antioxidant capacity assay, total superoxide dismutase assay, and lipid peroxidation assay were used to evaluate oxidative states of rats. 16S rRNA was used to study the impact of Nano-ZnO on the rat gut microbiome. Key findings Both ZnO-cp and ZnO-td exhibited low cytotoxicity while ZnO-s and ZnO-td exhibited prominent antibacterial activities. After a 28-day oral feeding with 1000 mg/kg Zn at dietary dosage, ZnO-s showed slight effect on causing oxidative stress in comparison with that of ZnO-cp and ZnO-td. Results of 16S rRNA sequencing analysis indicated that ZnO-td as a promising short-term nano-supplement can increase probiotics abundances like strains belonged to the genus Lactobacillus and provide the antipathogenic effect. Significance The results of the gut microbiome alteration by synthetic Nano-ZnO not only provide solution to exposure monitoring of environmental hazard, but rationalize their large-scale manufacture as alternative additive in the food chain.