Bmal1 deletion differentially alters the relative abundances at genus level in female and male mice. The relative abundances at genus level in male WT mice (green), male Bmal1 KO mice (blue), female WT mice (orange), and female Bmal1 KO mice (red). The relative abundances of Bacteroidales spp., F16 spp., and Clostridiaceae spp. were increased in both male and female Bmal1 KO mice. The relative abundances of Helicobacter and Lactobacillaceae spp. were decreased in both male and female Bmal1 KO mice. The relative abundances of Prevotella and Turicibacter were decreased in male but increased in female Bmal1 KO mice. The relative abundances of Rikenellaceae spp., Bacteroidales(other), Clostridiales spp., and Rikenella were increased in male Bmal1 KO mice. The relative abundance of Allobaculum, S24-7 spp. and Sutterella were decreased in male Bmal1 KO mice. The relative abundance of Peptococaceae spp. and Ureaplasma were increased in female Bmal1 KO mice. NWT = 5, NBmal1 KO = 6. Mean ± SEM shown. *P < 0.05, **P < 0.01, ****P < 0.0001 by Mann–Whitney test. Twenty two out of 23 remained significant when adjusted to control for a false positive rate of 5%.