Identification and determination of relatedness of lactobacilli using different DNA amplification methods

Several DNA amplification-based methods were used for identification and evaluation of the relation between lactobacilli isolated from breastfed full-term infant faeces (31 strains), dairy products (5 strains) and silage (1 strain). Twenty-seven strains isolated from infant faeces were identified as Lactobacillus rhamnosus (9), Lactobacillus gasseri (6), Lactobacillus paracasei (4), Lactobacillus fermentum (4), Lactobacillus salivarius (2), Lactobacillus plantarum (1), and Lactobacillus helveticus (1) using 10 species-specific polymerase chain reactions (PCRs), multiplex PCR for the Lactobacillus casei group, and sequencing of 16S rDNA. Four strains were not identified. Six strains isolated from dairy products and silage were identified as Lactobacillus rhamnosus. A repetitive extragenic palindromic polymerase chain reaction (rep-PCR) with primer (GTG)₅ and a randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) with primer M13 were used for confirmation of species identification. Fingerprints were used for evaluation of the relatedness of lactobacilli. Differences between strains from infant faeces, dairy products, and silage were not detected.