Phenotypic and genotypic aspects of Lactobacillus sanfranciscensis strains isolated from sourdoughs in Italy

Abstract

Physiological properties and genetic characteristics of 44 strains of Lactobacillus sanfranciscensis, isolated in Italy from sourdough samples for salted and sweet baked products, were investigated. Data were compared with those obtained for reference strains belonging to the same and to related species. Phenotypic analysis showed the presence of two main groups, the first including strains able to ferment glucose and maltose, the second including strains fermenting only maltose. Other few isolates exhibited individual different fermentation patterns. Genetic diversity was evaluated by using Amplified Ribosomal 16S rDNA Restriction Analysis and Amplified 16S-23S rDNA Spacer Region Analysis. Electrophoretical patterns of fragments generated by Hinf I indicated a polymorphism within 16S rDNA gene that allowed the subdivision ofLb. sanfranciscensis strains in two groups. The reliability to use Dde I and Hinf I 16S rDNA restriction analysis for differentiation of Lb. sanfranciscensis strains from the other phylogenetically related Lactic Acid Bacteria was demonstrated. The amplification of the intergenic spacer region produced a unique electrophoretical profile of three bands (approximately 300, 390 and 580 bp) for all Lb. sanfranciscensis strains; this analysis proved to be helpful for the discrimination of sourdough lactobacilli at species level, but was unable to distinguish among the isolates belonging to the same species. Results of grouping, obtained by genetic analyses, did not agree with those attained with phenotypic analysis, and no relation with the geographic area of isolation or type of product was found.