Genetic and technological characterization of wild Lactobacillus delbrueckii strains reveals low diversity but strong typicity. Ldelbrueckii_sn

Investigate the diversity of a given species could gave clues for the development of autochthonous starter cultures. However, few studies focused on the intraspecies diversity of Lactobacillus delbrueckii strains, a technological important lactic acid bacterium for the dairy industry. For this reason, Lactobacillus delbrueckii strains from the Saint-Nectaire PDO area were isolated and characterized. Genetic diversity was determined based on core genome phylogenetic reconstruction and pangenome analysis, while phenotypic assessments encompassed proteolysis and volatile compound production potential. In total, 15 L. delbrueckii ssp. lactis strains were isolated. The genetic analysis and proteolytic activities measurement revealed low variability among these Saint-Nectaire isolates, while substantial genetic variability was observed within the L. delbrueckii ssp. lactis subspecies as a whole. The volatile compound profiles slightly differed among strains and some isolates produced volatile compounds that could be of particular interest for cheese flavor development. While the genetic diversity among Saint-Nectaire isolates was relatively modest compared to overall subspecies diversity, their distinct characteristics and pronounced differentiation from publicly available genomes position them as promising candidates for developing autochthonous starter cultures for cheese production.