Characterization and species recognition of Lactobacillus plantarum strains by restriction fragment length polymorphism (RFLP) of the 16S rRNA gene

Twenty-one strains, labelled Lactobacillus plantarum or Lact. plantarum-like, and isolated from different natural sources, were characterized by restriction fragment length polymorphism (RFLP) of the 16S rRNA gene using HindIII and EcoRI cleaved chromosomal DNA, together with Lact. plantarum ATCC 14917(T), Lact. pentosus ATCC 8041(T), Lact. plantarum ATCC 10776 and Lact. plantarum ATCC 8014. The fermentation patterns on API 50CH were recorded at 30°C and 37°C for all strains. The phenotypes were heterogeneous, and the ability to ferment 17 of the 49 carbohydrates varied. The fermentation of some carbohydrates, for example D-raffinose and D-arabitol, was temperature-dependent. Strains having identical API profiles were separated by the plasmid profile. All strains but one (affiliated to Lact. casei) had identical 16S ribosomal DNA sequences (Lact. plantarum/Lact. pentosus). The RFLP study resulted in identical ribopatterns for 17 of the strains, including the type strain of Lact. plantarum (pattern A1). Four strains had related fragment patterns to that of Lact. plantarum sensu stricto; three of these strains had more than 60% DNA: DNA homology to the type strain of Lact. plantarum, and one had less than 50% DNA: DNA homology to Lact. plantarum ATCC 14917(T). Two strains had fragment patterns similar to the type strain of Lact. pentosus, and they had more than 80% DNA: DNA homology to Lact. pentosus ATCC 8041(T). One of the Lact. pentosus strains shared one band with the A1 pattern. The ribopatterns of Lact. plantarum were homogeneous (identical for 85% of the strains), irrespective of phenotype and source of isolation. RFLP of the 16S rRNA genes using EcoRI and HindIII might be used for species recognition of Lact. plantarum, but seems less suitable for strain typing.