PMC

Enumeration of lactobacilli (on MRS without erythromycin) in the feces of mice inoculated with the wild type (three mice) or the lsp mutant (four mice). Means and standard errors of the mean (bars) are shown.

In vivo and ex vivo adherence of L. reuteri 100-23C and the lsp mutant to the forestomach epithelium assessed by SEM. The bars represent one micrometer. Forestomach epithelium of an uninoculated RLF mouse (A) and of mice inoculated with wild-type L. reuteri 100-23C (B) and the lsp mutant strain (C). (D) Ex vivo adherence of wild-type L. reuteri 100-23C to epithelium.

Maps of L. reuteri 100-23 genes selectively induced in the murine gastrointestinal tract. (A) msrB; (B) xylA; (C) met. P, promoter regions identified by in vivo expression technology. The sequences downstream of msrB and met are depicted, including stop codons (grey), and stem-loop structures possibly representing rho-independent terminators are indicated by arrows.

SDS-PAGE of cell surface proteins. (A) Surface proteins of L. reuteri 100-23 extracted using a buffer containing SDS and 3-mercaptoethanol without (lane 1) and with (lane 2) sonication. The protein that was used for detection of the lsp gene is marked with an arrow. (B) Surface proteins of the wild type (lane 1) and the lsp mutant (lane 2) extracted with a buffer containing lysozyme and mutanolysin. Lsp is marked with an arrow.

Competition between wild-type and mutant strains. Mixtures of mutant and wild type (1:1) were used to inoculate RLF mice, and the percentage of mutants in the total Lactobacillus population was determined after 7 days. lsp (solid squares), xylA (open triangles up), msrB (solid circles), met (open triangles down). (F/S, forestomach; JEJ, jejunum; C, cecum). (A) Dose ca. 5 × 10⁷ bacteria per mouse. (B) Dose ca. 10⁵ bacteria per mouse. Values for individual mice are shown. Bars indicate medians.