Bioprospecting of native Metschnikowia pulcherrima strains for biocontrol and aroma enhancement in the wine production chain

Abstract

Metschnikowia pulcherrima is a well-studied non-conventional oenological yeast due to its positive contributions to winemaking as a bioprotective agent and as an aroma-enhancing starter in sequential fermentations with Saccharomyces cerevisiae (Binati et al., 2023; Canonico et al., 2023). The primary antagonistic property of this yeast is attributed to the production of pulcherrimin; it is effective against a wide range of spoilage yeasts and filamentous fungi, including Botrytis cinerea (Morata et al., 2019). In addition to its antimicrobial capabilities, M. pulcherrima also exhibits notable extracellular enzymatic activity, such as β-glucosidase and β-lyase activities, which enhance the aromatic compounds concentrations, improving the sensory profile of the wine (Canonico et al., 2023). Within this framework, the present study aimed to select novel M. pulcherrima strains exhibiting specific traits that could enhance wine aroma and serve as an effective and sustainable tool for managing fungal diseases in vineyards. Indeed, the vast phenotypic variability observed within these species of these technological characteristics required a bioprospecting strategy to find the most promising candidates. Here, we analyzed a collection of 136 native M. pulcherrima strains from different origins to evaluate their β-glucosidase and β-lyase activities, pulcherrimin production, and H₂S generation through targeted enzymatic assays. Three commercial strains were used for comparison. The results confirmed considerable strain-to-strain variability, particularly in β-glucosidase and β-lyase patterns, suggesting diverse biotechnological potential. The five high-performing native strains with superior aromatic release capabilities were then tested in vitro and in vivo to assess their effectiveness in controlling B. cinerea and their potential application on grapes. The intense biocontrol activity of the yeasts against the phytopathogen observed in the trials supports their use as protective agents during grape maturation to reduce fungal contamination risks. In conclusion, native M. pulcherrima strains emerge as promising multifunctional organisms, offering vineyard and winemaking management advantages. Their antimicrobial, enzymatic, and aromatic potential aligns with the growing demand for sustainable and environmentally friendly practices, making them a valuable natural alternative to chemical treatments in agricultural and oenological contexts.

Funding

This study was financially supported by the Italian Ministry of Agriculture, Food Sovereignty and Forestry (MASAF), project WINERED, Innovative interdisciplinary approaches for reducing the environmental impact of vinification.