Commensal adaptation of yeast Saccharomyces cerevisiae to grape-skin environment

Abstract

Abstract Saccharomyces cerevisiae, an essential player in alcoholic fermentation during winemaking, is rarely found in intact grapes. Although grape-skin environment is unsuitable for S. cerevisiae’s stable residence, S. cerevisiae or its relatives can increase population on grape berries after colonization during raisin production. Here, we addressed commensal adaptation of S. cerevisiae to grape-skin ecosystem. The yeast-like fungus Aureobasidium pullulans, a major grape-skin resident, exhibited broad spectrum assimilation of plant-derived carbon sources, including ω-hydroxy fatty acid, arising from degradation of plant cuticles. In fact, A. pullulans encoded and expressed esterase for cuticle degradation. When intact grape berries were used as a sole carbon source, non-fermentative A. pullulans or other residents accelerated S. cerevisiae’s alcoholic fermentation via increasing carbon availability. Thus, degradation and utilization of grape-skin materials by resident microbiota may account for their indigenous and S. cerevisiae’s commensal behaviors. Such plant-microbe symbiotic interaction may be a prerequisite for triggering spontaneous food fermentation.