Abstract: The effects of titanium dioxide (TiO2) nanoparticles on the intestinal microbiome and fecal metabolome in C57BL/6 mice were investigated and the correlation between the intestinal microbiome and fecal metabolome was analyzed. A control group and an experimental group were set up, which were orally administered with phosphate buffered saline (PBS) and 100 (mg/kg mb·d) of TiO2 nanoparticles for 13 continuous weeks, respectively. Blood glucose and lipids were measured. Furthermore, 16S rDNA gene sequencing and gas chromatography-mass chromatography (GC-MS) were used to identified the significantly differential microorganisms and metabolites between the two groups. Our results showed that compared with the control group, fasting blood glucose was significantly increased in the experimental group (P = 0.032). The relative abundance of Firmicutes, Allobaculum, Lactobacillus, and Oscillospira was increased. The differential metabolites were associated with the glycerolipid, galactose and tryptophan metabolic pathways. Firmicutes bacteria were negatively correlated with the differential metabolites, while bacteria from other phyla were positively correlated with the differential metabolites. Therefore, we infer that the subchronic toxicity of TiO2 nanoparticles to mice may be associated with abnormal glycolipid metabolism in feces.

Key words: titanium dioxide nanoparticles; gut; metabolome; microbiome