Safety traits, genetic and technological characterization of Lacticaseibacillus rhamnosus strains.

Lacticaseibacillus rhamnosus is a species extensively studied and employed in food production for its widely recognized probiotic properties. This study aimed to enhance understanding of this species by characterizing a diverse range of strains sourced from international collections or isolated from various origins, such as dairy products, sourdoughs, wine or must, and human bodily excreta. Initially, 60 Lbs. rhamnosus strains underwent genotypic characterization utilizing Rep-PCR, RAPD, and Sau-PCR techniques to evaluate their genetic relationships and eliminate clones. Subsequently, a phenotypic characterization was conducted to assess strain resistance to different stressors such as pH, NaCl, and ethanol. Furthermore, particular attention was given to food safety aspects concerning the potential use of these strains as food starters and/or probiotics. This included investigating antibiotic resistance profiles, antimicrobial capabilities, biogenic amines production, presence of genes associated with ethyl carbamate production, and the occurrence of technologically relevant enzymes such as monoamine oxidase and diamine oxidase. The analyses revealed significant genetic variability among strains, with limited correlation to their sources of isolation. Additionally, strain-specific phenotypic traits were observed, emphasizing the importance of thorough strain characterization for food applications. • High genetic diversity observed among Lacticaseibacillus rhamnosus strains. • Three strains particularly sensitive to antibiotics, also to vancomycin. • 85 % of the strains exhibited α or β haemolysis. • 18 out of 60 strains displayed mono-copper oxidase (MCO) activity. • Strain-specific traits emphasize the need for characterization and tailored selection. [ABSTRACT FROM AUTHOR]