Research Articles (Institute for Wine Biotechnology)
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Browsing Research Articles (Institute for Wine Biotechnology) by Subject "Brettanomyces bruxellensis"
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- ItemNon-saccharomyces killer toxins : possible biocontrol agents against brettanomyces in wine?(South African Society for Enology and Viticulture, 2015) Mehlomakulu, N. N.; Setati, M. E.; Divol, BenoitRed wine spoiled by the yeast Brettanomyces bruxellensis is characterised by off-odours commonly described as horse sweat, phenolic, varnish and band-aid. The growth of this yeast in wine is traditionally controlled by the use of sulphur dioxide (SO2). However, the concentration of SO2, the pH of the wine, the presence of SO2-binding chemical compounds in the wine, as well as the strain of B. bruxellensis, determine the effectiveness of SO2. Other chemical preservatives have been tested, but are not much more efficient than SO2, and methods used to clean barrels are only partially effective. Filtration of wine and the use of electric currents/fields are also reported to alter the physical and sensory properties of wine. In this context, alternative methods are currently sought to achieve full control of this yeast in wine. Killer toxins have recently been proposed to fulfil this purpose. They are antimicrobial compounds secreted by Saccharomyces and non-Saccharomyces yeasts, displaying killer activity against other yeasts and filamentous fungi. They are believed to play a role in yeast population dynamics, and this killer phenotype potentially could be exploited to inhibit the growth of undesired microorganisms within a microbial ecosystem such as that occurring in wine. In this review, non-Saccharomyces killer toxins are described and their potential application in inhibiting B. bruxellensis in wine is discussed in comparison to other tried methods and techniques.
- ItemTranscriptomics unravels the adaptive molecular mechanisms of Brettanomyces bruxellensis under SO2 stress in wine condition(Elsevier, 2020-03-10) Valdetara, Federica; Skalic, Miha; Fracassetti, Daniela; Louw, Marli; Compagno, Concetta; Du Toit, Maret; Foschino, Roberto; Petrovic, Uros; Divol, Benoit; Vigentini, IleanaSulfur dioxide is generally used as an antimicrobial in wine to counteract the activity of spoilage yeasts, including Brettanomyces bruxellensis. However, this chemical does not exert the same effectiveness on different B. bruxellensis yeasts since some strains can proliferate in the final product leading to a negative sensory profile due to 4-ethylguaiacol and 4-ethylphenol. Thus, the capability of deciphering the general molecular mechanisms characterizing this yeast species’ response in presence of SO2 stress could be considered strategic for a better management of SO2 in winemaking. A RNA-Seq approach was used to investigate the gene expression of two strains of B. bruxellensis, AWRI 1499 and CBS 2499 having different genetic backgrounds, when exposed to a SO2 pulse. Results revealed that sulphites affected yeast culturability and metabolism, but not volatile phenol production suggesting that a phenotypical heterogeneity could be involved for the SO2 cell adaptation. The transcriptomics variation in response to SO2 stress confirmed the strain-related response in B. bruxellensis and the GO analysis of common differentially expressed genes showed that the detoxification process carried out by SSU1 gene can be considered as the principal specific adaptive response to counteract the SO2 presence. However, nonspecific mechanisms can be exploited by cells to assist the SO2 tolerance; namely, the metabolisms related to sugar alcohol (polyols) and oxidative stress, and structural compounds.