Characterization and in vitro properties of potential probiotic Bifidobacterium strains isolated from breast-fed infant feces

Probiotics are live microorganisms that when administered in adequate amounts, confer health benefits on the host. In this study, 13 strains of Bifidobacterium were isolated from three samples of breast-fed infant feces. The isolates were identified based on conservative gene sequencing and phylogenetic analysis. In vitro tests included survival under simulated gastrointestinal tract conditions, aggregation, hydrophobicity, intestinal epithelial cell adhesion, antimicrobial activity, and antibiotic resistance according to international guidelines for probiotics. The results suggest that B. bifidum, B. adolescentis, and B. breve had high adhesive ability compared with B. longum and B. catenulatum/B. pseudocatenulatum group strains. In particular, B. bifidum IF3-211 has a highest adhesion index (8273 ± 247 and 18,009 ± 1476 adhering bacteria per 100 HT-29 and Caco-2 cells, respectively), far higher than the two reference strains, B. lactis Bb12 and B. longum BBMN68. B. adolescentis IF1-11 showed highest autoaggregation (82.52 ± 0.24 %) and coaggregation (45.59 ± 4.16 %) with L. monocytogenes among isolates. In conclusion, B. bifidum IF3-211 and B. adolescentis IF1-11 showed promising characteristics as probiotic candidates that have good potential for application in food industry.