Intestinal Colonization Characteristics of Lactobacillus spp. Isolated from Chicken Cecum and Competitive Inhibition Against Salmonella typhimurium

Probiotics are live microbial feed supplements which beneficially affect the host animal by improving its intestinal microflora. To select the best Lactobacillus spp. as a chicken probiotic, probiotic characteristics of 10 selected Lactobacillus strains isolated from chicken cecum or obtained from KCTC were investigated. The strains were examined for resistance to pH 2.0 and 0.3% oxgall, and adhesion to cecal mucus and cecal epithelial cells. All strains grew in MRS containing 0.3% oxgall. However, Lb. plantarum AYM-10, Lb. fermentum YL-3, AYM-3, and Lb. paracasei YL-6 showed relatively high resistance to 0.3% oxgall. Lb. fermentum YL-3, YM-5, AYM-3, and Lb. paracasei YL-6 survived 4 hours of incubation at pH 2.0. Lb. fermentum YL-3, KCTC 3112, and Lb. plantarum AYL-5 were strongly adhesive to cecal mucus, while the rest showed moderate or low adhesion. Lb. plantarum AYM-10, AYL-1, and AYL-5 had good adhering properties to cecal epithelial cells (30.7$\pm$10.82, 40.2$\pm$20.90, and 14.5$\pm$4.22, respectively). Lb. fermentum YL-3, AYM-3, and KCTC 3547 showed Intermediate adhesion ability, and Lb. plantarum showed better adhesion ability to cecal epithelial cells than Lb. fermentum. Attached Lb. fermentum YL-3 to cecum after 60 min incubation was confirmed using CLSM. Lb. fermentum YL-3 attached to a matrix which was composed of a mucus layer adjacent to intracrypts and pericryptal region. Some Lb. fermentum YL-3 bound to mucosal epithelial cells. From these results, Lb. fermentum YL-3 was selected as a chicken probiotic. In vivo trials of chicks inoculated with Lb. fermentum YL-3 had decreased Salmonella population in cecal contents and livers (p<0.5).