Genotyping, identification and multifunctional features of yeasts associated to Bosana naturally black table olive fermentations

Directly brined black table olives of Bosana variety are a traditional food product of Sardinia island (Italy), spontaneously fermented by yeasts among other microorganisms. However, as far as we know, the identification, biotechnological and probiotic potential of this yeast community has not been investigated yet. In this work, a total of 72 yeast isolates previously obtained from Bosana olive brines were first genotyped by Random Amplified Polymorphic DNA (RAPD-PCR) analysis with primer M13, and then identified by sequencing of D1/D2 domains of rDNA 26S gene. The dominant species were Wickerhamomyces anomalus and Nakazawaea molendini-olei, albeit Candida diddensiae, Candida boidinii, Zygotorulaspora mrakii, and Saccharomyces cerevisiae were also present in lower proportions. For the different biotypes of yeasts obtained, the multivariate analysis of their technological (esterase, lipase and β-glucosidase activities, growth in presence of oleuropein, resistance and susceptibility to NaCl) and probiotic (removal of cholesterol, gastric and pancreatic digestions, biofilms assays alone and in co-culture with Lactobacillus pentosus) features, showed that W. anomalus Wa1 exhibited the best technological characteristics, while S. cerevisiae Sc24 and C. boidinii Cb60 showed promising probiotic features. Therefore, they may have potential application as multifunctional starters, alone or in combination with lactic acid bacteria, during olive processing, albeit further studies are necessary to validate these results.