In this paper, we studied the spatial distribution and stress responses of resident Lactobacillus in various intestinal regions in order to clarify the ecological and functional properties of the microbes in mouse normal microflora. Lactobacillus reuteri and Lactobacillus intestinalis were identified as resident species by 16S rDNA analysis. Both lactobacilli were present in all regions of the intestinal tract (duodenum, jejunum+ileum, cecum and colon) at almost the same ratios based on colony shapes on LBS agar and the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) profiles using a genus-specific primer pair. Survivability of L. reuteri against heat shock, acid and bile salt treatments was markedly higher than that of L. intestinalis. Furthermore, almost all isolates of L. reuteri obtained from all intestinal regions grew in MRS broth with 0.5% bile salts, while almost all of the isolates of L. intestinalis failed to grow in the broth with 0.1% bile salts. These results suggest that resident lactobacilli, L. reuteri and L. intestinalis, in mice are able to colonize all intestinal regions with different environmental conditions, regardless of their stress response potentials.
Two hundred and forty nine Campylobacter isolates were discriminated between C. jejuni and C. coli by the hippurate hydrolysis test, three PCR methods using C. jejuni or C. coli specific primer sets, and the macrolide and quinolone line probe assay (MQ-LiPA). The results among the five methods were in agreement for all strains except for six strains, which were specified as C. coli by the hippurate hydrolysis test but as C. jejuni by the other methods. The data of 16S rDNA sequences in two out of these six strains, confirmed the strains were C. jejuni. These results suggest that MQ-LiPA is an effective method and can replace the hippurate hydrolysis test as other PCR methods.
In the present study, binding of bovine lactoferrin to bifidobacteria was demonstrated. This is the first report showing the binding of bovine lactoferrin to Bifidobactesrium spp. under a transmission electronic microscope using biotinylated bovine lactoferrin and gold-conjugated streptavidin. In addition, we confirmed that bovine lactoferrin-binding protein exists on the surface of bifidobacteria.