Figure 2.

Alterations in the fecal microbiota during tumorigenesis. Fecal samples were collected from control (Ctrl) and mid-ABX mice at various time points (ie, days 0, 56, 63, and 90) for taxonomy-based comparison of intestinal microbiota. (A) Principal coordinate analysis (PCoA) score plot based on the relative abundance of operational taxonomic units (OTUs) (97% similarity level). Bray Curtis dissimilarity matrices were generated to show the differences in the overall bacterial diversity across the samples. Each symbol represents a sample. (B) Shannon index showed different fecal microbial diversity in Ctrl and mid-ABX mice at various times. ∗P < .05. N = 3/group. (C and D) Relative abundance of bacterial phyla and families in the stool of Ctrl and mid-ABX mice at various times. Mid-ABX treatment resulted in relative abundance of the Enterobacteriaceae family (mainly Escherichia and unidentified genera). The label “D” with numbers indicated the taxonomic rank in the hierarchy. (E) Time-series plot of particular fecal bacterial taxa in the (a) Ctrl and (b) mid-ABX mice. Alterations in the relative bacterial abundance were indicated by the linear discriminant analysis score. Mid-ABX treatment depleted all of these bacteria on day 63. (F) PCoA plot of the relative abundance of OTUs in mouse stool after early, middle, and late ABX treatment. The 3 ABX regimens significantly disturbed the gut microbiota. (G) Shannon Index showed reductions in fecal microbial diversity by 3 ABX regimens. ∗P < .05. N = 4–6/group. (H) Percentages of bacterial family in the fecal microbiota of mice treated with early, middle, or late ABX. The Enterobacteriaceae family became predominant in stool samples in all 3 ABX regimens. N = 4–6/group.