Journal: bioRxiv

Article Title: Roles of bacterial growth competition systems in colonization of the murine gut

doi: 10.64898/2026.05.11.724384

Figure Lengend Snippet: (A) Schematic overview of mouse experiment with intact gut microbiota. (B) Untreated BALB/c mice were inoculated orally with 10 E. coli R12 and the number of CFU were determined by platin fecal material on MacConkey agar plates with or without Rifampicin. The data is plotted as CFU/g feces relative to day 1. Each dot represents one mouse (n = 8). P values were obtained using Mann-Whitney U test comparing the different days to day 1 p.i. *, p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001. (C) Enterobacteriaceae before the infection measured as cfu/ g feces on MacConkey agar plates . (D) Overview of the E. coli R12 genome. Genes encoding CDI systems ( cdiBAI ), colicins ( colBI, colMI, colYI ), transfer proteins ( tra ), P pili ( pap ) as well as a vacuolating toxin are indicated.

Article Snippet: E.coli R12 was isolated from the feces of rats acquired from Charles River laboratories.

Techniques: MANN-WHITNEY, Infection

Journal: bioRxiv

Article Title: Roles of bacterial growth competition systems in colonization of the murine gut

doi: 10.64898/2026.05.11.724384

Figure Lengend Snippet: (A, B) To check for CDI activity, wild-type E. coli R12 and deletion mutants were co-cultured for 24 h on M9Gly+casAA solid media with (A) R12 lacking cdiBAI1 or cdiBAI2 or (B) MG1655 lacking ompC or complemented with CDI immunities. (C) Indicated R12 inhibitors were cocultured with R12 targets lacking colYI, colBI or colMI at a 10:1 ratio for 24 h on solid M9Gly+CAA minimal media to check for colicin activity. (D) MG1655 lacking the indicated colicin receptor were incubated with culture supernatant from R12 wt, Δ colB , Δ colY or Δcolicins for 4 h before measuring optical density. Data are the averages ± SEM of at least three independent experiments. For statistical analyses, two-way ANOVA with Tukey’s correction for multiple comparison (A, C), unpaired t-test (B, E) In D, significance was determined towards the Δcolicin supernatant for each target. ns, not significant, *, p ≤ 0.05, **, p ≤ 0.01, ***, p ≤ 0.001, **** ≤ 0.0001, ***** ≤ 0.00001.

Article Snippet: E.coli R12 was isolated from the feces of rats acquired from Charles River laboratories.

Techniques: Activity Assay, Cell Culture, Incubation, Comparison

Journal: bioRxiv

Article Title: Roles of bacterial growth competition systems in colonization of the murine gut

doi: 10.64898/2026.05.11.724384

Figure Lengend Snippet: (A) Untreated BALB/c mice were inoculated orally with 10 wildtype or mutant R12 lacking all five toxin delivery systems (Δcomplete). The CFU levels were determined by plating fecal material on MacConkey agar plates with or without Rifampicin. The data is plotted as CFU/g feces relative to day 1. Each dot represents one mouse (N=7 wt and n=8 Δcomplete). P values were obtained using Mann-Whitney U test comparing the mutant strain to WT. *, p ≤ 0.05, ** p ≤ 0.01. (B) 16S sequencing results. (C) The prevalence of Enterobacteriaceae at D0 and D8 was compared for wildtype and Δcomplete using Mann-Whitney U test. ** p ≤ 0.01. (D) Statistically significant differences in Muribaculaceae species annotated as ASV24 and ASV47 in table S2 between mice colonized with R12 WT. Efficient colonization (n=3) is shown as yellow bars and non-efficient colonization (n=5) as pink bars.. Error-bars are SEM. Statistical significance was determined using unpaired t-test. * = P<0.05. (E) Overview of the E. coli NF_6988 genome. Genes encoding CDI systems, colicin E7, microcin PDI, and transfer proteins ( tra ) are indicated. (F) Coculture experiments of E. coli R12 wildtype and Δcomplete, and NF_6988 mixed at 10:1, 1:1 or 1:10 starting ratio on solid M9Gly+CAA minimal media for 24 h. (G) Correlation of the initial ratio and end ratio of R12 to resident E. coli microbiota was analyzed using Spearmans’s correlation. (H) The x-axis lists the 34 carbon sources in the Biolog PM1 and PM2 MicroPlates found to be different between MG1655, R12 and NF_6988. Carbon sources shaded in blue could be used by a strain as defined by a threshold of background-subtracted A 590nm . Carbon sources utilized by R12 but not by NF_6988 are highlighted in bold and carbon sources utilized by R12 but not MG1655 are highlighted in red.

Article Snippet: E.coli R12 was isolated from the feces of rats acquired from Charles River laboratories.

Techniques: Mutagenesis, MANN-WHITNEY, Sequencing

Journal: bioRxiv

Article Title: Roles of bacterial growth competition systems in colonization of the murine gut

doi: 10.64898/2026.05.11.724384

Figure Lengend Snippet: (A) Schematic overview of mouse experiment. Antibiotic-treated BALB/c mice were orally inoculated with 10 E. coli K12 MG1655 and subsequently challenged with 10 of either wildtype or mutant E. coli R12. Each day fecal samples were collected and CFU counts were determined. (B) Mice pre-colonized with MG1655 were challenged with wildtype, or mutants lacking both CDI systems (ΔCDI), all three colicins (Δcolicins) or CDI systems and colicins (Δcomplete), and CFU counts of MG1655 and R12 were determined from fecal samples. Each dot represents one mouse. P values were obtained using Mann-Whitney U test comparing the mutant strains to WT. *, p ≤ 0.05.

Article Snippet: E.coli R12 was isolated from the feces of rats acquired from Charles River laboratories.

Techniques: Mutagenesis, MANN-WHITNEY