Extended Data Fig. 7. Bacterial-to-human DNA ratio associated with time since birth.

(a) Bacterial 16S copy number per gram feces increased with time since birth (two-sided test of Spearman correlation, ρ = 0.5, P = 6×10⁻⁶, n = 85, 3 samples excluded due to no data on time since birth). (b) Bacterial 16S copy number per μL extracted DNA increases with time since birth (two-sided test of Spearman correlation, ρ = 0.5, P = 7×10⁻⁶, n = 85). (c) The bacterial-to-human DNA ratio is higher in samples collected after 16 hours with low human DNA relative to others (two-sided Mann-Whitney test, P = 4×10⁻¹¹, n₁ = 32 samples collected after 16 hours with low human DNA, n₂ = 53 others). Samples with a bacterial-to-human DNA ratio above unity are labeled with the subject ID. (d) The bacterial-to-human DNA ratio is higher in samples collected