Germfree mice (n=5/group) were colonized with wildtype, the lpxF deletion mutant (solid lines), and complemented (lpxF,lpxF+; dashed lines) B. thetaiotaomicron strains 7 days prior to initiation of inflammation by C. rodentium infection (A), no further treatment (B), infection with a non-inflammatory C. rodentium tir mutant (C), or exposure to 3% DSS ad libitum for 7 days (black bar) (D). Infection with C. rodentium strains is indicated by black arrowheads and relative C. rodentium abundances are reported as percent of total fecal DNA (shaded bars); error bars represent standard deviation and asterisks indicate significant (p<0.01) differences.