Fig. 1

Microbial population changes in response to the antibiotic treatments and host responses to V. cholerae infection in each treatment group. Adult mice were divided into four groups and treated with PBS (a), streptomycin (SM) (b), Vancomycin (VAN) (c), or clindamycin (CL) (d). Treatments were performed as described in “Methods” section. Fecal matter was collected at the end of the treatment, and microbial DNA was extracted for 16S rRNA gene amplicon sequencing. Microbial compositions at the phylum level are shown in pie charts. Relative abundance of each phylum is proportional to the arc length of each slice. Five dominant phyla (i.e., Bacteroidetes, Firmicutes, Verrucomicrobia, Deferribacteres, and Proteobacteria) numbered from 1 to 5 are indicated with different colors. Following treatment, mice in each group were infected with 5 × 10⁸ CFU of N16961 cells. At 24 h post-infection, fecal matter collected from each group (e–h) was subject to microbial composition analysis. *The Proteobacteria phylum shown in panel H includes V. cholerae at 8.81% abundance. At the end of the infection period, mouse gastrointestinal tracks were extracted from each group to visualize infection-induced phenotypes (i–l). Red arrowheads shown in panel l indicate regions of small intestine with fluid accumulation, while a black arrowhead shows the cecum, where the size is remarkably smaller than in other mice. Dotted lines in panels i–l indicate the large intestines