Evaluation of physiological properties of yeast strains isolated from olive oil and their in vitro probiotic trait.

Virgin olive oil contains a biotic fraction represented by rich microbiota, including yeasts. The aim of this study was to investigate some physiological properties and the in vitro probiotic potential of yeast strains previously isolated from Italian virgin olive oil. Eleven yeast strains belonging to the species Candida adriatica, Candida diddensiae, Nakazawaea molendini-olei, Nakazawaea wickerhamii, Wickerhamomyces anomalus, and Yamadazyma terventina were used in this study and compared with the reference yeast Saccharomyces boulardii. Present research has demonstrated that unlike Saccharomyces boulardii which produce only satured and monounsatured fatty acids (MUFAs), the olive oil-borne yeast strains also synthesize polyunsatured fatty acids (PUFAs) in quantities greater than those found in olive oil, which provide health benefits. The survival in gastric and pancreatic juices, which is important for probiotic yeasts because it allows them to cross the human intestinal tract, has reached a maximum of 100% when yeast cells were coated with olive oil. Cholesterol was removed by 50% of the studied yeast strains, and among them, the best results were reached by the strains 2032 and 2033 of W. anomalus which appear the best probiotic candidate in terms of the in vitro probiotic trait evaluated. Further experiments are underway to confirm this findings.