# Harnessing the Enzymatic Potential of Indigenous Yeast Strains: Screening and Evaluation for Biocontrol and Oenological Advancements

## TL;DR

This study explores indigenous yeast strains for their potential in winemaking and biocontrol, identifying those with useful enzymatic activities.

## Contribution

The study introduces a comprehensive screening of indigenous yeast strains for multiple enzymatic and biocontrol functions in viticulture.

## Key findings

- Four yeast species showed chitinolytic activity, with H. uvarum 116 and T. delbrueckii Sut94 exhibiting the highest cell-associated and extracellular activities, respectively.
- P. guilliermondii ZIM 624 displayed the most comprehensive enzymatic profile and strong inhibition patterns against fungal growth.
- Field trials showed that P. guilliermondii ZIM 624 had more pronounced effects on 'Pinot noir' than on 'Pinot gris' in an integrated disease management approach.

## Abstract

The growing emphasis on sustainability, regional distinctiveness, and spontaneous fermentation in winemaking necessitates a more comprehensive understanding of local yeast populations and their functional mechanisms. In total, 115 indigenous yeast strains were examined for their enzymatic activities of potential vitivinicultural significance. The yeasts were screened for chitinase activity (biocontrol potential), glycosidase activity (terpene release), β-lyases (thiol release), and sulfite reductases (off-flavor formation), followed by quantitative analysis of the selected subsets. Yeasts were further evaluated for inhibition of fungal mycelial growth, VOC-mediated inhibition, and tolerance to commonly applied fungicides. Pre-field selection was refined using the niche overlap index and grapevine leaf disc assay. The results confirmed chitinolytic activity in four species; all strains exhibited hydrolase activities, with H. uvarum 116 displaying the highest cell-associated activity (6.32 U/g), while T. delbrueckii Sut94 showed the highest extracellular activity (1.36 U/g). β-glucosidase and β-lyase activities were widespread, whereas hydrogen sulfide production was infrequent. P. guilliermondii ZIM 624 showed the most comprehensive overall enzymatic profile, together with strong inhibition patterns. A field trial on Pinot cultivars (V. vinifera L.) further evaluated P. guilliermondii ZIM 624 within an integrated disease management approach, with responses being more pronounced in ‘Pinot noir’ than in ‘Pinot gris’.