Characterization and evaluation of anti-Salmonella enteritidisactivity of indigenous probiotic lactobacilli in mice

Abstract

AbstractLactobacilli (n= 24), isolated from human infants and yogurt, showed variablein vitroactivity againstSalmonella enteritidis(8.0 ± 1.0 to 16.6 ± 0.5 mm) and other gut pathogens (9.0 ± 1.0 to 15.3 ± 0.5 mm), as determined by a well diffusion assay. The isolates were identified asLimosilactobacillus fermentum(FY1, FY3, FY4, IL2, and IL5),Lactobacillus delbrueckii(FY6 and FY7),Lactobacillussp. (IL7), andLactobacillus gasseri(IL12). All isolates showed variablein vitrotolerance to acidic pH for 3 h and visible growth at pH 4 and in the presence of 0.3% ox-bile. The antibiotic susceptibility profile ofLactobacillusisolates indicated resistance against vancomycin, ciprofloxacin, streptomycin, and lincomycin. Isolates had variable auto-aggregation and showed variable capabilities to co-aggregate withS. enteritidis. Based on all tested parameters,L. fermentumIL2,L. fermentumIL5, andL. gasseriIL12 were selected for co-culture experiments, followed byin vivoevaluation in Balb/c mice. All the selected isolates resulted in a 100% reduction inS. enteritidisin broth.Lactobacillusisolates efficiently colonized mouse guts and inhibitedS. enteritidiscolonization. Overall, there was ≥99.06% and ≤4.32 Mean log10reduction inSalmonellacounts in mice feces within 7 days. The study, thus, provided characterized lactobacilli that could be considered as potential ingredients for probiotic formulations intended to preventS. enteritidisinfection in humans.