Bmal1 deletion alters bacterial abundances in fecal microbiota in mice. Fecal microbiota compositions from WT and Bmal1 KO mice at all time points across the day were compared. (A) Fecal microbiota composition from individual WT mice (blue) and Bmal1 KO mice (red) were clustered separately according to Principal Coordinate Analysis of Unweighted UniFrac (Left) and Weighted UniFrac (Right) distances. The percentages of variation explained by principal coordinates PC1 and PC2 are indicated on the x and y axes. (B) The relative abundance of Proteobacteria was decreased and that of TM7 was increased in Bmal1 KO mice, whereas those of Bacteroidetes and Firmicutes were not altered. (C) The inferred absolute abundance of Baceroidetes, Firmicutes, and Proteobacteria were decreased in Bmal1 KO mice, whereas that of TM7 was not altered. NWT = 5, NBmal1 KO = 6. **P < 0.01, ***P < 0.001, ****P < 0.0001 by Mann–Whitney test. All remained significant when adjusted to control for a false positive rate of 5%.