Characterization of Novel Lachancea thermotolerans Strains for Application in Table Olive Fermentation

Lachancea thermotolerans is a non-Saccharomyces yeast characterized by its biotechnological potential, due, among other reasons, to its capacity to produce L-lactic acid and its impact on the organoleptic profiles of final fermented products. While its traits have been widely studied in fermented beverages and vinification, its potential use in other fermented foods, such as table olives, has been poorly studied. For this reason, the characterization and laboratory screening of Lachancea thermotolerans strains were performed in the present study. In this context, the potential use of forty L. thermotolerans strains in Spanish-style table olives was discussed based on pH and salt concentration tolerance, two key stress factors in the production process. Furthermore, the effect of oleuropein-the most abundant polyphenol in raw drupes-on L-lactic acid production was described to better understand and predict the behavior of L. thermotolerans under real conditions. In addition to stress resistance and L-lactic acid production, the suitability of the strains was assessed through their resistance to cycloheximide and copper, key indicators of tolerance to antimicrobial agents and agricultural residues. Finally, Principal Component Analysis of mixed data (PCAmix) and Hierarchical Clustering on Principal Components (HCPC) were performed to stratify and describe the intraspecific variability of this species, leading to the preselection of fifteen promising L. thermotolerans strains for use as starter cultures in Spanish-style table olive elaboration.