Microbiologia
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11840
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Resultados da Pesquisa
Item Screening of yeasts isolated from brazilian environments for the 2-Phenylethanol (2-PE) production(Biotechnology and Bioprocess Engineering, 2018-06) Lima, Lorena Azevedo de; Diniz, Raphael Hermano Santos; Queiroz, Marisa Vieira de; Fietto, Luciano Gomes; Silveira, Wendel Batista daPhenylethanol alcohol, or 2-phenylethanol (2-PE) production by yeasts has been considered a promising alternative to its chemical synthesis. In order to evaluate the potential of yeast strains isolated from different Brazilian environments, we evaluated the 2-PE production of 267 strains. Among them, the Kluyveromyces marxianus CCT 7735 yeast stood out as being the best 2-PE producer. The K. marxianus CCT 7735 growth was impaired by 2-PE; nevertheless, this effect is less pronounced than the inhibition reported for certain Saccharomyces cerevisiae strains. The maximum 2-PE titer obtained under optimized conditions was 3.44 g/L, 28% higher than the titer achieved under unoptimized conditions. The optimized conditions were: 30ºC, and glucose and L-phe concentrations of 3.0 and 4.0 g/L, respectively. Moreover, the specific production rate of 2-PE increased twofold compared to the unoptimized conditions.Item Optimizing ethanol production by thermotolerant Kluyveromyces marxianus CCT 7735 in a mixture of sugarcane bagasse and ricotta whey(Food Science and Biotechnology, 2015-08) Ferreira, Priscila Gonçalves; Silveira, Fernando Augusto da; Santos, Raquel Cristina Vieira dos; Genier, Hugo Leonardo André; Diniz, Raphael Hermano Santos; Ribeiro Jr., José Ivo; Fietto, Luciano Gomes; Passos, Flávia Maria LopesThe simultaneous saccharification and fermentation (SSF) process is a promising strategy to obtain ethanol from cellulosic biomass. In this study, sugarcane bagasse was supplemented with ricotta whey to increase the sugar, vitamin, and trace metal concentrations in the fermentation medium. The optimum conditions for SSF ethanol production from a mixture of sugarcane bagasse and ricotta whey produced by Kluyveromyces marxianus CCT 7735 were evaluated considering five factors: cellulase concentration, cellulosic biomass concentration, pH, temperature, and agitation. The highest ethanol yield was 49.65 g/L with a cellulosic biomass of 80 g/L, pH value of 5.05, agitation at 65 rpm and temperature of 39.2°C. The results demonstrated that a mixture of the cellulosic residue of sugarcane bagasse and ricotta whey is promising for ethanol production because the ethanol yield in the mixture was higher than that in single substrate of sugarcane bagasse.Item Optimizing ethanol production by thermotolerant Kluyveromyces marxianus CCT 7735 in a mixture of sugarcane bagasse and ricotta wh(Food Science and Biotechnology, 2015-05-01) Ferreira, Priscila Gonçalves; Silveira, Fernando Augusto da; Santos, Raquel Cristina Vieira dos; Genier, Hugo Leonardo André; Diniz, Raphael Hermano Santos; Ribeiro Jr., José Ivo; Fietto, Luciano Gomes; Passos, Flávia Maria Lopes; Silveira, Wendel Batista daThe simultaneous saccharification and fermentation (SSF) process is a promising strategy to obtain ethanol from cellulosic biomass. In this study, sugarcane bagasse was supplemented with ricotta whey to increase the sugar, vitamin, and trace metal concentrations in the fermentation medium. The optimum conditions for SSF ethanol production from a mixture of sugarcane bagasse and ricotta whey produced by Kluyveromyces marxianus CCT 7735 were evaluated considering five factors: cellulase concentration, cellulosic biomass concentration, pH, temperature, and agitation. The highest ethanol yield was 49.65 g/L with a cellulosic biomass of 80 g/L, pH value of 5.05, agitation at 65 rpm and temperature of 39.2°C. The results demonstrated that a mixture of the cellulosic residue of sugarcane bagasse and ricotta whey is promising for ethanol production because the ethanol yield in the mixture was higher than that in single substrate of sugarcane bagasse.Item Transcriptome analysis of the thermotolerant yeast Kluyveromyces marxianus CCT 7735 under ethanol stress(Applied Microbiology and Biotechnology, 2017-08-03) Diniz, Raphael Hermano Santos; Villada, Juan C.; Alvim, Mariana Caroline Tocantins; Vidigal, Pedro Marcus Pereira; Vieira, Nívea Moreira; Lamas-Maceiras, Mónica; Cerdán, María Esperanza; González-Siso, María-Isabel; Lahtvee, Petri-Jaan; Silveira, Wendel Batista daThe thermotolerant yeast Kluyveromyces marxianus displays a potential to be used for ethanol production from both whey and lignocellulosic biomass at elevated temperatures, which is highly alluring to reduce the cost of the bioprocess. Nevertheless, contrary to Saccharomyces cerevisiae, K. marxianus cannot tolerate high ethanol concentrations. We report the transcriptional profile alterations in K. marxianus under ethanol stress in order to gain insights about mechanisms involved with ethanol response. Time-dependent changes have been characterized under the exposure of 6% ethanol and compared with the unstressed cells prior to the ethanol addition. Our results reveal that the metabolic flow through the central metabolic pathways is impaired under the applied ethanol stress. Consistent with these results, we also observe that genes involved with ribosome biogenesis are downregulated and gene-encoding heat shock proteins are upregulated. Remarkably, the expression of some gene-encoding enzymes related to unsaturated fatty acid and ergosterol biosynthesis decreases upon ethanol exposure, and free fatty acid and ergosterol measurements demonstrate that their content in K. marxianus does not change under this stress. These results are in contrast to the increase previously reported with S. cerevisiae subjected to ethanol stress and suggest that the restructuration of K. marxianus membrane composition differs in the two yeasts which gives important clues to understand the low ethanol tolerance of K. marxianus compared to S. cerevisiae.