Dominance of non-Saccharomyces yeasts in artisanal mezcal fermentations

TL;DR

This study shows that non-Saccharomyces yeasts dominate the fermentation process in mezcal production, challenging previous assumptions about the role of Saccharomyces.

Contribution

The study reveals that non-Saccharomyces yeasts are the dominant fungal genera in mezcal fermentations, with no dominance of Saccharomyces.

Findings

Non-Saccharomyces yeasts like Hanseniaspora, Pichia, and Zygosaccharomyces were the dominant fungal genera in mezcal fermentations.

Saccharomyces was not the dominant yeast in any of the 15 fermentations analyzed.

Lactic acid bacteria and acetic acid bacteria were the dominant bacterial groups.

Abstract

Mezcal is a spirit obtained from the fermentation and distillation of juices obtained from different agave species. It is one of the distilled beverages with great sociocultural value in different regions of Mexico, and in recent years, it has also gained great economic importance. It is known to present differences in its flavour, thanks to the richness of compounds incorporated within the spirit, which vary according to the agave species used, the microbial population present and the processes involved in its manufacture. This variety reflects the richness of local traditions and the craftsmanship behind its production. The main objective of the present work was to explore parameters that could impact fungal and bacterial diversity. The microbiome of bacteria and yeasts present in fermentations in the same distillery, in two different years and with three different agave species was investigated by metataxonomic analysis obtained from the sequencing of regions V3–V4 for bacteria and ITS1 for yeasts. The results showed that the dominant fungal genera in the fermentations correspond to non-Saccharomyces yeasts (Hanseniaspora, Pichia and Zygosaccharomyces). A major finding was that Saccharomyces was not the dominant yeast in any of the 15 fermentations characterized. The dominant bacteria belong to the groups of lactic acid bacteria and acetic acid bacteria. The statistical analysis of the alpha and beta diversities shows that the main statistical differences are seen in the year of fermentation rather than in the species of agave used. Finally, the microbial consortium was composed of the same genera during the different fermentations studied; the fundamental difference was the dominant genus in each fermentation.

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