Probiotic properties of two Lactobacillus strains in vitro

Two lactobacilli, L. rhamnosus MA27/6B and L. acidophilus MA27/6R, both of which are used in a commercial feed additive (Sorbial(R), France), were studied in vitro to see if they satisfied the general selection criteria for probiotic strains. Their ability to resist gastrointestinal conditions was demonstrated, as survival was not affected by lysozyme, low pH or bile. Behavior towards antibiotics was shown to be similar to that of other lactobacilli. Both strains demonstrated antibacterial activity towards pathogens involved in infectious diseases in animals (Escherichia coli, Salmonella, Clostridium, Pasteurella...), although L. rhamnosus MA27/6B was found to be more effective. These antibacterial activities may be attributable to the production of bacteriocin-like compounds. The Caco-2 cell line was used as an in vitro model of the intestinal epithelium to test the adhesion properties of these lactobacilli: L. acidophilus MA27/6R displayed greater adhesion (7 times greater) than L. rhamnosus MA27/6B. These in vitro findings suggest that both strains could have probiotic potential.