Differentiation of Lactobacillus isolates from infant faeces by SDS-PAGE and rRNA-targeted oligonucleotide probes

Isolates of lactobacilli from infant faeces phenotypically characterized as Lactobacillus paracasei subsp. paracasei (six strains), Lact. rhamnosus (s ix strains), Lact. gasseri (three strains), Lact. acidophilus (one strain) and Lact. fermentum/reuteri (three strains) according to recent classificat ion systems were subjected to SDS-PAGE of whole cell proteins and rRNA-targ eted oligonucleotide probe hybridization, in order to confirm the phenotypi c characterization and elucidate the exact taxonomic position of the three strains that had properties between fermentum and reuteri. Results suggeste d a good agreement between the phenotypic characterization, SDS-PAGE and rR NA-targeted oligonucleotide probe hybridization for strains of all species except for the Lact. fermentum/reuteri strains. Results obtained by rRNA pr obes suggested a possible phylogenetic relatedness of the strains to Lact. reuteri. Isolates from infant faeces with interesting probiotic properties could be used as components of fermented milk products.