Characterization of technological and probiotic properties of indigenous Lactobacillus spp. from south Brazil

In this study, we isolated Lactobacillus spp. from bovine raw milk and artisanal cheese from southern Brazil, and evaluated their technological and probiotic potential to select new isolates for producing healthy fermented dairy foods with differentiated tastes and flavours. We obtained 48 new lactobacilli isolates, which were isolated from raw milk (38) and cheese (10). These bacterial isolates were closely related with ten species: Lactobacillus paracasei (50% of the isolates), L. parabuchneri (15%), L. pentosus (13%), L. zeae (4%), L. plantarum (4%), L. otakiensis (4%), L. casei (4%), L. harbinensis (2%), L. diolivorans (2%), and L. rhamnosus (2%). Isolates CH112 and CH131 showed the greatest acidification potential, reducing the pH of milk to below 5.3 after incubation for 6 h at 32 °C. Considering proteolytic activity and diacetyl production, isolates ML88a, ML04, and ML12 showed the most promising results. Isolate ML12 showed 100% survival rate when inoculated in gastric juice at pH 2.5. The evaluation of antibacterial activity of the lactobacilli showed that the pathogens Listeria monocytogenes, Staphylococcus aureus, Salmonella enteritidis, and Salmonella Typhimurium were strongly inhibited by the pure lactobacilli cultures. Five Lactobacillus isolates (ML01, ML04, ML12, ML88, and CH139) showed both technological and probiotic characteristics. Principal Component Analysis (PCA) was used to investigate correlations among technological and probiotic characteristics, and identified new promising lactobacilli isolates for exploring their characteristics. This study reveals the importance of selecting new microorganisms with potential applicability in the food industry for developing functional foods with differentiated aromas and flavours.