Navegando por Autor "Alvarez, Florencia"

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Biotechnological potential of yeast isolates from cachaça : the Brazilian spirit.
(2015) Conceição, Luís Eduardo Fernandes Rodrigues da; Saraiva, Margarete Alice Fontes; Diniz, Raphael Hermano Santos; Oliveira, Juliana; Barbosa, Gustavo Dimas; Alvarez, Florencia; Correa, Lygia Fátima da Mata; Mezadri, Hygor; Coutrim, Maurício Xavier; Afonso, Robson José de Cássia Franco; Lucas, Cândida Manuel Ribeiro Simões; Castro, Ieso de Miranda; Brandão, Rogélio Lopes
This study identified phenotypic traits appropriate for biotechnological applications of 118 yeasts isolated from cachaça distilleries. Different properties were verified: capacity to use alternative carbon sources; ability to tolerate high concentrations of sucrose, ethanol, methanol, aluminum and zinc as well as different pH values and foam production. Pichia guilliermondii and Pichia anomala strains were identified as the most promising ones for application in the second-generation biofuel industry, showing ability to grow on high glycerol concentrations. Other isolates, identified as Saccharomyces cerevisiae, produced bioethanol comparable to the industrial strains, and were therefore ideal for use in the first-generation ethanol industry. Some of these strains also showed high resistance to aluminum, as observed in sugarcane juice, and to intercycle washings with diluted sulphuric acid, as performed in the industrial bioethanol production process. In summary, yeast isolates from cachaça distilleries displayed robustness and phenotypic plasticity, which makes them interesting for biotechnological applications.
Detailed search for protein kinase(s) involved in plasma membrane H+-ATPase activity regulation of yeast cells.
(2015) Pereira, Renata Rebeca; Castanheira, Diogo Dias; Teixeira, Janaina Aparecida; Bouillet, Leoneide Érica Maduro; Ribeiro, Erica Milena de Castro; Trópia, Maria José Magalhães; Alvarez, Florencia; Correa, Lygia Fátima da Mata; Mota, Bruno Eduardo Fernandes; Conceição, Luís Eduardo Fernandes Rodrigues da; Castro, Ieso de Miranda; Brandão, Rogélio Lopes
This study displays a screening using yeast strains deficient in protein kinases known to exist in Saccharomyces cerevisiae. From 95 viable single mutants, 20 mutants appear to be affected in the glucose-induced extracellular acidification. The mutants that are unaffected in calcium signaling were tested for their sensitivity to hygromycin B. Furthermore, we verified whether the remaining mutants produced enzymes that are appropriately incorporated at plasma membrane. Finally, we measure the kinetic properties of the enzyme in purified plasma membranes from glucose-starved as well as glucose-fermenting cells. We confirmed the kinase Ptk2 involvement in H+−ATPase regulation (increase of affinity for ATP). However, the identification of the kinase(s) responsible for phosphorylation that leads to an increase in Vmax appears to be more complex. Complementary experiments were performed to check how those protein kinases could be related to the control of the plasma membrane H+−ATPase and/or the potential membrane. In summary, our results did not permit us to identify the protein kinase(s) involved in regulating the catalytic efficiency of the plasma membrane H+−ATPase. Therefore, our results indicate that the current regulatory model based on the phosphorylation of two different sites located in the C-terminus tail of the enzyme could be inappropriate.
Quality improvement and geographical indication of cachaça (Brazilian spirit) by using local selected yeast strains.
(2016) Barbosa, Edilene Alves; Souza, Magalhães Teixeira de; Diniz, Raphael Hermano Santos; Santos, Fernanda Godoy; Oliveira, Fábio Faria; Correa, Lygia Fátima da Mata; Alvarez, Florencia; Coutrim, Maurício Xavier; Afonso, Robson José de Cássia Franco; Castro, Ieso de Miranda; Brandão, Rogélio Lopes
Aims: In order to improve the quality and to create a biological basis for obtainment of the protected denomination of origin (PDO), indigenous yeast were isolated and characterized for use in Salinas city (the Brazilian region of quality cachac a production). Material and methods: Seven thousand and two hundred yeast colonies from 15 Salinas city distilleries were screened based on their fermentative behaviour and the physicochemical composition of cachac a. Molecular polymorphic analyses were performed to characterize these isolates. Results: Two Saccharomyces cerevisiae strains (nos. 678 and 680) showed appropriate characteristics to use in the cachac a production: low levels of acetaldehyde and methanol, and high ethyl lactate/ethyl acetate ratio respectively. They also presented polymorphic characteristics more closely related between themselves even when compared to other strains from Salinas. Conclusions: The application of selected yeast to cachac a production can contribute for the improvement of the quality product as well as be used as a natural marker for PDO. Significance and Impact of the Study: This study suggests that the use of selected yeast strains could contribute to obtain a cachac a similar to those produced traditionally, while getting wide acceptation in the market, yet presenting more homogeneous organoleptic characteristics, and thus contributing to the PDO implementation.
Variable flocculation profiles of yeast strains isolated from cachaça distilleries.
(2014) Alvarez, Florencia; Correa, Lygia Fátima da Mata; Araújo, Thalita Macedo; Mota, Bruno Eduardo Fernandes; Conceição, Luís Eduardo Fernandes Rodrigues da; Castro, Ieso de Miranda; Brandão, Rogélio Lopes
In cachaça production, the use of yeast cells as starters with predictable flocculation behavior facilitates the cell recovery at the end of each fermentation cycle. Therefore, the aim of this work was to explain the behavior of cachaça yeast strains in fermentation vats containing sugarcane through the determination of biochemical and molecular parameters associated with flocculation phenotypes. By analyzing thirteen cachaça yeast strains isolated from different distilleries, our results demonstrated that neither classic biochemical measurements (e.g., percentage of flocculation, EDTA sensitivity, cell surface hydrophobicity, and sugar residues on the cell wall) nor modern molecular approaches, such as polymerase chain reaction (PCR) and real-time PCR (q-PCR), were sufficient to distinctly classify the cachaça yeast strains according to their flocculation behavior. It seems that flocculation is indeed a strain-specific phenomenon that is difficult to explain and/or categorize by the available methodologies