Comparative studies on potential probiotic characteristics of Lactobacillus acidophilus strains

Background: Probiotics are live microorganisms present in food and dietary supplements that beneficially affect the individual by improving the intestinal microbial balance properties. Their market value and biological potential is enormous because of their health-promoting properties. Therefore, comparative studies on probiotic potential of three selected strains of Lactobacillus acidophilus were carried out during this work. Method: The selected strains of Lactobacillus acidophilus (NCIM 2660, NCIM 2903 and NCIM 2285) were assessed for tolerance to pH (pH 2.5) and oxgall (0.3%), adhesion to Caco-2 cells, antimicrobial properties against test microorganisms and susceptibility to antibiotics. Results: The distinguished characteristics of strain NCIM 2903 were high acid tolerance, antagonistic activity against all test micro-organisms and adhesion to Caco-2 cells (225±33 cells adhering to 100 Caco-2 cells). Strain NCIM 2285 exhibited bile tolerance and inability to grow in presence of five of the antibiotics used. Strain NCIM 2285 indicated moderate adhesion to Caco-2 cells. The strain NCIM 2660 was unable to grow in presence of any of the twelve antibiotics. In contrast, control plates without discs of antibiotics exhibited confluent growth. It was a desirable feature. However, NCIM 2660 exhibited poor adhesive property. The optimum temperature of growth for all three strains was found to be 37oC. Conclusions: Significant differences in the probiotic characteristics of the three strains were recorded. In the cumulative assessment, strain NCIM 2903 could be regarded as the potential probiotic contender. These studies will help in selecting the probiotic micro organisms in a more rational manner for further applications.