Effect of Kluyveromyces thermotolerans on Saccharomyces cerevisiae during fermentation processes

NALLY, M.C.; PONSONE, M.L.; GODOY, S. DEL C.,; PESCE, V.M.; TORO M.E.; VAZQUEZ F.; CHULZE, S.N.

Bari

Congreso; II International Symposium on Postharvest Pathology: Using Science to Increase Food Availability; 2015

International Society for Horticultural Science (ISHS), the International Society of Plant Pathology (ISPP), the Italian Phytopathological Society (SIPaV) and EXPO2015.

Introduction: Fungal diseases are one of the main reasons for economic losses in viticulture in pre and postharvest. Aspergillus section Nigri species have been reported as agents of black grape rot. Antagonistic microorganisms as biological control of plant pathogens are a sustainable alternative to synthetic fungicides. In previous studies, our group isolated two yeasts strains (Kluyveromyces thermotolerans RCKT4 and RCKT5) that inhibited Aspergillus growth and decreased OTA accumulation in wine grapes. However, there are no data about the effects of K. thermotolerans biofungicides during oenological fermentations. The aim of this work was to evaluate the impact of biofungicides in pure and mixed cultures with S. cerevisiae BSc203 (an oenological strain) during microfermentations. Matherials and Methods: Pure and mixed cultures (1% BSc203-99% biofungicide; 50% BSc203-50% biofungicide; 99% BSc203-1% biofungicide) were inoculated in commercial must. All fermentation samples were periodically withdrawn and spread on WLN- Agar plates (Log10 UFC/ml), in which both colonies strains can be differentiated. Results: In co-cultures, Saccharomyces (BSc2013)/Kluyveromyces (RCKT5, RCKT4), BSc203 concentration was no significantly different to pure BSc203 concentration, except in the co-culture 99% RCKT4-1% S. cerevisiae, at the end of fermentations (22 days). Cells concentration of BSc203 (in 99% K.th./1%S.c.) was 1.38 Log10 cycle lower than in its pure culture. Conclusion: K. thermotolerans RCKT4 affect the growth of S. cerevisiae when this biofungicide was inoculated in high proportions.