Rapid Identification of Lactobacillus acidophilus and Bifidobacterium by a 16S rRNA PCR Method

Background: Probiotics are live microorganisms that, when administered, have beneficial effects on human health. Hence, various probiotic organisms belonging to the genera Lactobacillus and Bifidobacterium are being increasingly used in food and pharmaceutical products. For regulatory compliance, simple and reliable analytical methods are required for selective enumeration of different probiotic organisms present in food and pharmaceutical formulations. Objective: This study aimed to establish a rapid PCR-based method for the identification and differentiation of Lactobacillus acidophilus and Bifidobacterium strains. Methods: Species-specific and genus-specific primers for Lactobacillus and Bifidobacterium were designed based on their 16S rRNA gene sequence. Genomic DNA of different Lactobacillus and Bifidobacterium strains were subjected to PCR with annealing temperature specific for respective primer pairs. Results: Lactobacillus acidophilus primers gave positive PCR results only with Lactobacillus acidophilus strains and not with other Lactobacillus species, whereas Bifidobacterium genus-specific primers gave positive PCR results with most of the Bifidobacterium strains. Conclusion: The three species-specific L. acidophilus primer pairs and three genus-specific primer pairs of Bifidobacterium used in this study could easily identify and differentiate Lactobacillus acidophilus and Bifidobacterium with high specificity.