Fig. 4
Effect of TiO2 NPs on gut microbiota after oral administration for 90 days. a Top four relative abundance of bacteria at phylum-level. b Ratio of relative abundance between Firmicutes and Bacteroidetes, which may be closely related to adverse health effects of hosts. Comparison of Alpha Diversity of gut microbiota between different groups using Chao1 (c), ACE (d), and PD_Whole_Tree (e). f Comparison of Beta Diversity of gut microbiota between different groups using non-linear model NMDS method based on OTUs information in samples. * represents statistical difference (p < 0.05)