Commensalism in yeast bacteria interactions: a study of the relationship between Metschnikowia pulcherrima and Oenococcus oeni

Mestrado Vinifera Euromaster - Viticulture and Enology - Instituto Superior de Agronomia

This research work addresses the under explored interaction between malolactic bacteria and non-Saccharomyces yeast, specifically commercial strains of Metschnikowia Pulcherrima and Oenococcus oeni. Chemically defined media and two chardonnay juices were used to evaluate sequential and co-inoculated malolactic fermentation strategies, investigating the effect of M. Pulcherrima on O. oeni viability and malolactic fermentation kinetics. L-malic acid consumption, and bacteria viability were tracked during fermentation, along with sampling for organic acid analysis. Our findings showed the addition of M. pulcherrima significantly influenced malolactic fermentation kinetics and increased O. oeni bacteria viability in chemically defined media, and select Chardonnay treatments. Further work is investigating the source of commensalism between M. pulcherrima and O. oeni. Exploring alternative strain pairs and understanding non- Saccharomyces and bacteria interactions will help increase winemakers control when implementing co-inoculation strategies for malolactic fermentation. This has a promising application in the industrial production of sparkling base wine, increasing malolactic fermentation efficiency and closing the gap for potential spoilage associated with conducting malolactic after alcoholic fermentation

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