# First Report of Pichia bruneiensis in a Spontaneous Sugarcane Juice Fermentation: A Case Study from an Artisanal Distillery in the Ecuadorian Amazon

## TL;DR

This study reports the first occurrence of Pichia bruneiensis in sugarcane juice fermentation in an Ecuadorian Amazon distillery.

## Contribution

The first documented case of Pichia bruneiensis in spontaneous sugarcane juice fermentation in the Ecuadorian Amazon.

## Key findings

- Three distinct yeast morphotypes were isolated from sugarcane juice fermentation.
- Pichia bruneiensis was identified in the final fermentation stage with ≥99% sequence identity.
- Yeast diversity decreased during fermentation, with one morphotype persisting until the end.

## Abstract

Spontaneous fermentation of sugarcane juice for the production of artisanal sugarcane spirits in the Ecuadorian Amazon is driven by native microbial communities; however, the yeast diversity involved in this process remains poorly characterized. In this descriptive case study, sugarcane juice samples were collected from a single artisanal distillery at three fermentation stages (0, 48, and 96 h). Yeasts were isolated using selective culture techniques, yielding three distinct morphotypes (Y01, Y02, and Y03). A progressive reduction in morphological diversity was observed during fermentation, with isolate Y01 persisting at the final stage (96 h). Differences in crystal violet staining indicated variability in cellular metabolic activity among the isolates under the conditions tested. Biochemical characterization using the API 20C AUX system, combined with molecular identification based on ITS rDNA sequencing, was performed for isolate Y01, which showed ≥99% sequence identity with Pichia bruneiensis. To the best of our knowledge, this study represents the first report of P. bruneiensis associated with spontaneous sugarcane juice fermentation in an artisanal distillery from the Ecuadorian Amazon. These findings provide a descriptive baseline on yeast biodiversity in this traditional fermentation system and support future studies aimed at the functional characterization of native yeasts involved in artisanal sugarcane spirit production.