CHARACTERIZATION OF LACTOBACILLUS-SAKE ISOLATES FROM DRY-CURED SAUSAGES BY RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS OF THE 16S RIBOSOMAL-RNA GENE

Lactobacillus sake strains originally isolated from dry-fermented saus ages were characterized by phenotypic and genotypic methods, including DNA-DNA hybridization, restriction fragment length polymorphism (RFLP ), and 16S rDNA sequencing analysis, in order to establish their taxon omic position and relation to well defined reference species. Initiall y, isolates of Lact. sake showing a characteristic phenotype (melibios e-positive, maltose- and arabinose-negative) were identified by DNA-DN A hybridization. Subsequently, RFLP studies using EcoRI and HindIII as restriction enzymes, and cDNA from Escherichia coli or 16S rDNA from Lact. sake strains as probes, showed distinct polymorphism levels. Thu s, EcoRI-digested DNA probed with cDNA from E. coli disclosed the pres ence of a unique cluster for the meat isolates tested, allowing their differentiation from the reference type strain. When HindIII-digested DNA was hybridized with the cDNA probe, strain-specific patterns were obtained, showing a higher discrimination power. Considerable strain d ifferentiation was also observed when EcoRI and HindIII digests were h ybridized with 16S rDNA probes. Finally, sequence analysis of the 16S rDNA from one isolate also revealed a certain degree of genetic variab ility with respect to the reference strain of Lact. sake.