| Summary: | The purpose of this study was to explore the inoculated fermentation of cv. Kalamata natural black olives using selected strains of yeast cultures with multifunctional potential. For this purpose, five yeast starters belonging to <i>Candida boidinii</i> (four starters) and <i>Saccharomyces cerevisiae</i> (one starter), previously isolated from table olive fermentation of the same variety and screened for their technological characteristics and probiotic potential, were inoculated in brines at the beginning of fermentation. Microbial populations (lactic acid bacteria, yeasts, and <i>Enterobacteriaceae</i>), pH, titratable acidity, organic acids, and ethanol were monitored during fermentation for a period of 5 months. At the same time, the survival of each starter was assessed by culture-dependent molecular identification at the beginning (0 days), middle (75 days), and final stages (150 days) of fermentation in the brines and olives (at the end of the process only). The results revealed the coexistence of yeasts and lactic acid bacteria (LAB) throughout fermentation in most processes and also the absence of <i>Enterobacteriaceae</i> after the first 20 days of brining. The population of yeasts remained 2 log cycles below LAB counts, except for in the inoculated treatment with <i>C. boidinii</i> Y28, where the yeast starter prevailed from day 60 until the end of the fermentation, as well as in the inoculated treatment with <i>C. boidinii</i> Y30, where no LAB could be detected in the brines after 38 days. At the end of the process, LAB ranged between 4.6 and 6.8 log<sub>10</sub> CFU/mL, while yeasts were close to 5.0 log<sub>10</sub> CFU/mL, except for the inoculated fermentation with <i>C. boidinii</i> Y27 and spontaneous fermentation (control), in which the yeast counts were close to 3.5 log<sub>10</sub> CFU/mL. At the end of fermentation, the recovery percentage of <i>C. boidinii</i> Y27 was 50% in the brines and 45% in the olives. <i>C. boidinii</i> Y28 and <i>S. cerevisiae</i> Y34 could be recovered at 25% and 5% in the brine, respectively, whereas neither starter could be detected in the olives. For <i>C. boidinii</i> Y30, the recovery percentage was 25% in the brine and 10% in the olives. Finally, <i>C. boidinii</i> Y31 could not be detected in the brines and survived at a low percentage (10%) in the olives.
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