Fig. 4: K. oxytoca toxin production is regulated through sugar availability and is important in GF mice.
a, Colony-forming units of S. Typhimurium grown alone or in co-culture with MK01 WT, sKO or cWT in tryptone with various sugars. Mean and s.e.m. of n = 3 experiments with n = 3 replicates. Con, control; GS, glycosides. b, Relative gene expression of npsA in MK01 WT in TB with added galactose or lactose. Mean ± s.e.m. one experiment with n = 3 samples with n = 3 replicates. Gal, galactose; Lac, lactose. c, Quantification of TM and TV in the SN of MK01 WT in TB media with galactose or lactose. Mean ± s.e.m. of n = 3 independent cultures. d, CI of S. Typhimurium in co-cultures with K. oxytoca MK01 WT, sKO or cWT in various sterile caecal contents. Mean ± s.e.m. of n = 4 experiments with n = 2 replicates. The dashed line indicates the inoculation ratio. e, Relative gene expression of npsA in MK01 WT in various caecal contents. Mean ± s.e.m. of one representative experiment from n = 3 samples with n = 3 replicates. f,g, Quantification of TM and TV (f) and of indole (g) in the SN of MK01 WT in various caecal contents. Mean ± s.e.m. of n = 3 independent cultures. h,i, Free lactose/galactose levels (h) and total free carbohydrate levels (i) from SNs of caecal content. Mean ± s.e.m. of n = 6 mice measured in duplicates. j–o, GF mice were colonized with MK01 WT or sKO or left untreated 4 days before infection. On day 0 mice were orally infected with S. Typhimurium, and BWL, survival and faecal colonization were monitored until day 6 p.i. j, BWL over the time of infection. d.p.i., days post infection; NS, not significant. k, Survival of various S. Typhimurium infected groups. Log-rank (Mantel–Cox) test between curves with ****P < 0.0001. l–n, Faecal colony-forming units of S. Typhimurium (l) and K. oxytoca (m), and resulting CI at various time points (n). DL, level of detection. The solid line indicates equal amounts of bacteria (index = 1). o, Faecal TM and TV in WT colonized animals. In j–n, mean ± s.e.m. of n = 2 experiments with n = 8 (PBS), n = 9 (WT) or n = 10 (sKO) mice per group. In b and e, ordinary one-way ANOVA with Holm–Šídák’s multiple comparisons test with *P < 0.05, ****P < 0.0001. In d and f–i, ordinary one-way ANOVA with Tukey’s multiple comparisons test between groups with *P < 0.05, **P < 0.01, ***P < 0.001 and ****P < 0.0001. In c and j–n, one-way ANOVA with Dunn’s multiple comparisons test between groups. In j and l–n, two-tailed Mann–Whitney U-test between two groups with *P < 0.05, **P < 0.01, ***P < 0.001 and ****P < 0.0001. See also Extended Data Fig. 6.
