Molecular Methods Used for the Identification of Potentially Probiotic Lactobacillus reuteri Strains

Forty potentially probiotic Lactobacillus strains as well as reference strains of different genera were grown under standardised conditions. Cell masses were harvested and DNA was isolated. For identification, all strains were subjected to genus-specific polymerase chain reaction (PCR), and the affiliation with the genus Lactobacillus was confirmed for all isolates. Using two species-specific primer-pairs for Lactobacillus reuteri, specific amplicons were observed for eight of the forty investigated strains. For differentiation, these eight strains as well as the reference strains of the species L. reuteri and closely related species were subjected to randomly amplified polymorphic DNA (RAPD)-PCR using fourteen arbitrary primers. Two selected strains as well as probiotic and common reference strains were further investigated applying pulsed field gel electrophoresis (PFGE). With the latter two methods, individual profiles were found for most strains, but no difference between probiotic and common strains could be made out