Fungal diversity of lye treated olives. Characterizing Yeast Populations during Spanish Table Olive Fermentation: Insights from Metataxonomic Analysis

This study delved into the dynamic interplay between physicochemical factors and the evolution of yeast populations during the fermentation of Spanish-style table olives. Through a metataxonomic analysis of the Internal Transcribed Spacer (ITS) region, we aimed to unveil the fungal composition at various fermentation stages—both with and without inoculation. The findings showcased a synchronized uptick in lactic acid bacteria counts alongside yeast proliferation, particularly in the samples subjected to inoculation. Metataxonomic investigation unearthed noteworthy disparities across different fermentation time points. However, when considering the fermentation matrix or the inoculation process, no statistically significant differences emerged, a pattern underscored by Principal Component Analysis. Statistical scrutiny pinpointed two distinct Amplicon Sequence Variants (ASVs)—Candida and Aureobasidium—as accountable for the observed variances among the groups. Notably, Candida exhibited a marked reduction in presence on day 83 compared to day 0, whereas Aureobasidium demonstrated a significantly heightened presence on day 0 relative to both day 24 and day 83. At the inception of the process, prominent genera were Mycosphaerella (19.82%) and Apohysomyces (16.31%), hitherto unreported in the context of table olive processing. However, their prevalence dwindled to nearly negligible levels from day 24 onwards (<2%).