Lactobacillus hilgardii and Lactobacillus brevis DNA analysis by restriction fragment length polymorphism (RFLP)

Fifteen heterofermentative lactobacilli belonging to the Lactobacillus hilardii and Lactobacillus brevis were studied. In a DNA/DNA hybridization test most of them give the expected answer since their DNA hybridized with the reference strain DNA probe from the same species. However, strains (of L. brevis) strongly hybridized with L. hilgardii ATCC 8290. This raised doubts on their taxonomical position because they had previously been identified as L. brevis. Restriction enzymes (EcoRI, BamHI, HindIII, PstI) were used in an RFLP (restriction fragment length polymorphism) study of these strains. 16S + 23S rRNA from Escherichia coli constituted the probe. Statistical analysis of all the patterns (i.e. four enzymes and 15 strains) led to the construction of a dendrogram. Finally, two main branches corresponded well with the results of conventional identification, because they associated L. hilgardii strains on one side and L. brevis on the other side. In addition, each branch was divided into subgroups. This method proved adapted to ribotype all the 15 strains except two, using these four enzymes.