Browsing by Author "Plaza, Verónica"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Cell wall modifications in Saccharomyces cerevisiae wine yeast through adaptive laboratory evolution with Tebuconazole
    (2025) Becerra Bevensee, Kevin Andrew; Plaza, Verónica; Castillo, Luis; Godoy Olivares, Liliana
    Saccharomyces cerevisiae is the most used yeast for wine production around the world. Several characteristics make this yeast the wine yeast of excellence; among them is a great tolerance to higher concentrations of sugar and alcohol. Nevertheless, some compounds could have detrimental effects on its development like pesticides. Tebuconazole is one of the most common fungicides used in agriculture, belonging to the largest group of fungicides, the triazoles chemical group, that act on sterol biosynthesis. Yeasts have different responses to compensate for stress, and changes in their cell wall are one of the main ones. This work aimed to obtain new variants of S. cerevisiae through adaptive laboratory evolution (ALE) using Tebuconazole as selection pressure and to evaluate changes in yeast cell wall structure, composition, and fermentative behavior. Three new variants of S. cerevisiae were obtained. Analysis of the relative expression of genes associated with cell wall components showed that the third variant obtained YCPUC209C, had overexpression of genes FKS1, FKS3, CHS3, and SED1 in comparison with the original strain, also morphological analysis through TEM microscopy showed that YCPUC209C had an increase of 22.2% of cell wall thickness and 19% increase in the amount of glucan in comparison to the original strain. These cell wall changes were accompanied by hypersensitive to β-1,3-glucanase activity. Increased tolerance to pesticides Buprofezin and Spirotetramat presence during alcoholic fermentation was achieved by YCPUC209C, improving fermentative efficiency parameter. Changes in cell wall structure and composition reported in this work open new lines of analysis like the evaluation of yeast pesticide dissipation capacity since it is reported that components, such as glucan and chitin, can bond to these contaminants, reducing their residues in the wine.
  • Thumbnail Image
    Item
    Recent Advances in the Study of the Plant Pathogenic Fungus Botrytis cinerea and its Interaction with the Environment
    (2017) Castillo, Luis; Plaza, Verónica; Larrondo Castro, Luis Fernando; Canessa, Paulo
  • Thumbnail Image
    Item
    Step-Wise Ethanol Adaptation Drives Cell-Wall Remodeling and ROM2/KNR4 Activation in Brettanomyces bruxellensis
    (2025) Hernández-Cabello, Leslie; Rojas-Torres, Nachla; Godoy Olivares, Liliana; G-Poblete, Camila; Concha, Yarabi; Plaza, Verónica; Castillo, Luis; Mora-Montes, Héctor M.; Ganga, María Angélica
    Brettanomyces bruxellensis has been described as the main spoilage microorganism in wines due to its ability to produce volatile phenols, which negatively impact the final product’s organoleptic properties. This yeast can grow and survive in environments that are too nutritionally poor and stressful for other microorganisms, and one of the stressful conditions it can endure is the high alcohol content in wine. In this study, cell wall morphology and the expression of some genes related to its composition were characterized under increasing ethanol concentrations to establish a possible ethanol resistance mechanism. B. bruxellensis LAMAP2480 showed greater resistance to β-1,3-glucanase activity when grown in media supplemented with 5% or 10% ethanol compared with the control assay (without ethanol). Transmission electron microscopy showed no significant differences in cell wall thickness during the different adaptation stages. However, the amount of wall polysaccharides and chitin briefly increased at 1% ethanol but returned to baseline at 5% and 10%. The amount of wall-associated protein increased progressively with each increment in ethanol concentration. In addition, overexpression of the ROM2 and KNR4/SMI1 genes was observed at 10% ethanol. These results suggest that the integrity of the cell wall might play an important role in the adaptation of B. bruxellensis to an ethanol-containing medium.