Biological diversity of carbon assimilation among isolates of the yeast Dekkera bruxellensis from wine and fuel-ethanol industrial processes.

Dekkera bruxellensis is considered a spoilage yeast in winemaking, brewing and fuel-ethanol production. However, there is growing evidence in the literature of its biotechnological potential. In this work, we surveyed 29 D.

Production of ethanol fuel from enzyme-treated sugarcane bagasse hydrolysate using d-xylose-fermenting wild yeast isolated from Brazilian biomes.

In this study, we evaluated the potential of yeasts isolated from Amazon to produce second-generation ethanol from sugarcane bagasse delignified with alkaline hydrogen peroxide and hydrolysed with commercial enzyme preparation. The best efficiency savings in glucose and release of xylose were determined by considering the solids and enzyme loads. Furthermore, we selected UFMG-CM-Y473 strain with the best fermentative parameters.

On the catabolism of amino acids in the yeast Dekkera bruxellensis and the implications for industrial fermentation processes.

In the last years several reports have reported the capacity of the yeast Dekkera (Brettanomyces) bruxellensis to survive and adapt to the industrial process of alcoholic fermentation. Much of this feature seems to relate to the ability to assimilate limiting sources of nutrients, or somehow some that are inaccessible to Saccharomyces cerevisiae, in particular the sources of nitrogen. Among them, amino acids (AA) are relevant in terms of beverage musts, and could also be important for bioethanol.

Glutamine: a major player in nitrogen catabolite repression in the yeast Dekkera bruxellensis.

In the present work we studied the expression of genes from nitrogen central metabolism in the yeast Dekkera bruxellensis and under regulation by the Nitrogen Catabolite Repression mechanism (NCR). These analyses could shed some light on the biological mechanisms involved in the adaptation and survival of this yeast in the sugarcane fermentation process for ethanol production. Nitrogen sources (N-sources) in the form of ammonium, nitrate, glutamate or glutamine were investigated with or without the addition of methionine sulfoximine, which inhibits the activity of the enzyme glutamine synthetase and releases cells from NCR.

Production of sensory compounds by means of the yeast Dekkera bruxellensis in different nitrogen sources with the prospect of producing cachaça.

The distilled spirit made from sugar cane juice, also known as cachaça, is a traditional Brazilian beverage that in recent years has increased its market share among international distilled beverages. Several volatile compounds produced by yeast cells during the fermentation process are responsible for the unique taste and aroma of this drink. The yeast Dekkera bruxellensis has acquired increasing importance in the fermented beverage production, as the different metabolites produced by this yeast may be either beneficial or harmful to the end-product.

Oxygen-limited cellobiose fermentation and the characterization of the cellobiase of an industrial Dekkera/Brettanomyces bruxellensis strain.

The discovery of a novel yeast with a natural capacity to produce ethanol from lignocellulosic substrates (second-generation ethanol) is of great significance for bioethanol technology. While there are some yeast strains capable of assimilating cellobiose in aerobic laboratory conditions, the predominant sugar in the treatment of lignocellulosic material, little is known about this ability in real industrial conditions. Fermentations designed to simulate industrial conditions were conducted in synthetic medium with glucose, sucrose, cellobiose and hydrolyzed pre-treated cane bagasse as a different carbon source, with the aim of further characterizing the fermentation capacity of a promising Dekkera bruxellensis yeast strain, isolated from the bioethanol process in Brazil.

The influence of nitrate on the physiology of the yeast Dekkera bruxellensis grown under oxygen limitation.

A previous study showed that the use of nitrate by Dekkera bruxellensis might be an advantageous trait when ammonium is limited in sugarcane substrate for ethanol fermentation. The aim of the present work was to evaluate the influence of nitrate on the yeast physiology during cell growth in different carbon sources under oxygen limitation. If nitrate was the sole source of nitrogen, D.

5-Hydroxymethylfurfural induces ADH7 and ARI1 expression in tolerant industrial Saccharomyces cerevisiae strain P6H9 during bioethanol production.

The aims of this work were to obtain, by evolutionary engineering, an industrial strain of Saccharomyces cerevisiae tolerant to high concentrations of HMF and to determine the expression levels of genes previously described as responsible for this tolerance. Cells were grown under anaerobic and oxygen limited conditions, in the presence of glucose or sucrose as carbon sources. P6H9 strain presented high expression levels for genes ADH7 and ARI1 in presence of HMF.

A new set of reference genes for RT-qPCR assays in the yeast Dekkera bruxellensis.

The yeast Dekkera bruxellensis has been recently regarded as an important microorganism for bioethanol production owing to its ability to convert glucose, sucrose, and cellobiose to ethanol. The aim of this work was to validate a new set of reference genes for gene expression analysis by quantitative real-time PCR in D. bruxellensis and compare the influence of the method of choice for quantification of mRNA levels with the reliability of our data.

Quantitative aerobic physiology of the yeast Dekkera bruxellensis, a major contaminant in bioethanol production plants.

Dekkera bruxellensis has been described as the major contaminant yeast of industrial ethanol production, although little is known about its physiology. The aim of this study was to investigate the growth of this yeast in diverse carbon sources and involved conducting shake-flask and glucose- or sucrose-limited chemostats experiments, and from the chemostat data, the stoichiometry of biomass formation during aerobic growth was established. As a result of the shake-flask experiments with hexoses or disaccharides, the specific growth rates were calculated, and a different behavior in rich and mineral medium was observed concerning to profile of acetate and ethanol production.

Construction of integrative plasmids suitable for genetic modification of industrial strains of Saccharomyces cerevisiae.

The development of efficient tools for genetic modification of industrial yeast strains is one of the challenges that face the use of recombinant cells in industrial processes. In this study, we examine how the construction of two complementary integrative vectors can fulfill the major requirements of industrial recombinant yeast strains: the use of lactose assimilation genes as a food-grade yeast selection marker, and a system of integration that does not leave hazardous genes in the host genome and involves minimal interference in the yeast physiology. The pFB plasmid set was constructed to co-integrate both LAC4-based and LAC12-based cassettes into the ribosomal DNA (rDNA) locus to allow yeast cells to be selected in lactose medium.

The ability to use nitrate confers advantage to Dekkera bruxellensis over S. cerevisiae and can explain its adaptation to industrial fermentation processes.

The yeast Dekkera bruxellensis has been regarded as a contamination problem in industrial ethanol production because it can replace the originally inoculated Saccharomyces cerevisiae strains. The present study deals with the influence of nitrate on the relative competitiveness of D. bruxellensis and S.