SELECTION OF POTENTIALLY PROBIOTIC LACTIC ACID BACTERIA FROM AN ITALIAN TRADITIONAL RAW MILK CHEESE

Objective: The growing interest in fermented foods is mainly due to their contribution to a healthy gut microbiota, mediated by foodborne microorganisms with potential benefits. The aim of this study was the characterization of fermentative microbiota of Pecorino di Picinisco, an Italian traditional PDO cheese obtained from ovine raw milk, and the evaluation of possible probiotic activities of selected strains. Methods: For lactic acid bacteria isolation, two selective media (MRS and LM17) and two growth temperatures (30 and 37 °C) were used. Strain selection and characterization at species level were performed by comparing Rep-PCR profiles and subsequent 16S rDNA sequencing. Adhesion to intestinal cells and antibiotic (ampicillin, erythromycin, tetracycline) susceptibility were evaluated. Results: From a total of forty isolates, eleven strains were identified and three of them, representative of the different species found (Lactococcus lactis, Lactiplantibacillus plantarum and Latilactobacillus curvatus) were selected to test probiotic activities, by comparing them to the reference strain Lacticaseibacillus rhamnosus GG (LGG). Since adhesion to gut mucosa is one of the main selection criteria for probiotics, Caco-2 cells were used as an in vitro model of human intestinal epithelium to evaluate the adhesion capacity of the three strains, which resulted able to adhere to cells, at levels comparable to those of LGG. Concerning safety, all the strains were susceptible to ampicillin, erythromycin and tetracycline, supporting their possible food and pharma applications. Conclusions: These promising results lay the ground for further investigations, aimed at confirming the probiotic potential of the three strains examined in this study.