RESUMO
An intergeneric osmotolerant hybrid yeast, PB2, was used together with the parental strains to study glycerol and arabitol production in batch culture. This fusion product was previously obtained by protoplast fusion between Torulaspora delbrueckii and Saccharomyces cerevisiae. Polyols and biomass production were determined in batch culture under aerobic conditions. Under the conditions tested, using PB2 hybrid and both parental strains, the best results were obtained with the hybrid. Arabitol reached a final concentration of 70 g/l and glycerol was increased to up to 50 g/l.
Assuntos
Glicerol/metabolismo , Hibridização Genética , Protoplastos/fisiologia , Saccharomycetales/metabolismo , Álcoois Açúcares/metabolismo , Meios de Cultura , Fermentação , Microbiologia Industrial/métodos , Pressão Osmótica , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Saccharomycetales/genética , Saccharomycetales/fisiologiaRESUMO
In the beginning there was yeast, and it raised bread, brewed beer, and made wine. After many not days but centuries and even millenia later, it was named Saccharomyces cerevisiae. After more years and centuries there was another yeast, and it was named Schizosaccharomyces pombe; now there were two stars in the yeast heaven. In only a few more years there were other yeasts, and then more, and more, and more. The era of the non-conventional yeasts had begun.
Assuntos
Leveduras/classificação , Leveduras/fisiologia , Biotecnologia/métodos , Leveduras/genéticaRESUMO
The dynamics of metabolism has been shown to be involved in the triggering of events that are concurrent with sporulation of the budding yeast Saccharomyces cerevisiae. Indeed, quantitative correlations have been demonstrated between sporulation and the rate of carbon substrate or oxygen consumption, and the fluxes through gluconeogenic and glyoxylate cycle pathways. The results suggest that an imbalance between catabolic and anabolic fluxes influences the occurrence of the differentiation process. The hypothesis that the initiation of sporulation is triggered by the accumulation of an intracellular metabolite is confronted with the notion that intermediary metabolism and the expression of genes involved in sporulation interact to trigger the differentiation process. Several pieces of evidence indicate that derepression of the gluconeogenic pathway is crucial for the initiation of sporulation. One of the possible pathways through which glucose repression hampers sporulation might be the repression of gluconeogenesis as well as that of respiratory activity, in turn modulating the expression of IMEL++. The stages defined in the dynamics of sporulating cultures, namely readiness and commitment, are related to metabolic events associated with sporulation. An interpretation in terms of metabolic flux dynamics is given to the reversal of commitment occurring when the normal progression to sporulation is somehow blocked. The quantitative data are here integrated in a model attempting to simulate the dynamics of metabolic as well as cellular events during sporulation. The model is envisaged as a test of the hypothesis that an imbalance between anabolism and catabolism is involved in initiation of the sporulation process. It is proposed that such an imbalance may be a signal for differential gene expression associated with the differentiation pathway.
Assuntos
Saccharomyces cerevisiae/fisiologia , Diferenciação Celular , Metabolismo Energético , Meio Ambiente , Regulação Fúngica da Expressão Gênica , Genes Fúngicos , Meiose , Modelos Biológicos , Esporos FúngicosRESUMO
Quantitative studies of metabolic fluxes during Saccharomyces cerevisiae sporulation on acetate in the presence of the glucose analog, 2-deoxy glucose (2dG) are reported. We have studied the inhibition of sporulation and associated catabolic or anabolic fluxes by 2dG. Sporulation frequencies decreased from 50% to 2% asci per cell at 2dG concentrations in the range of 0.03 to 0.30 g l-1, respectively. Under the same conditions, the acetate consumption flux was inhibited up to 60% and the glyoxylate cycle and gluconeogenic fluxes decreased from 0.7 and 0.3 mmol h-1 g-1 dw, respectively, to negligible values. We observed a linear correlation of the acetate consumption rate with the sporulation frequency by varying the 2dG concentration. The linear correlation was also verified between the frequency of sporulation and the fluxes through glyoxylate cycle and gluconeogenic pathways. In addition, the same association of inhibition of sporulation and metabolic fluxes was found in other S. cerevisiae strains displaying different potentials of sporulation. The results presented suggest that inhibition of sporulation in the presence of the glucose analog may be attributed, at least in part, to the inhibition of anabolic fluxes and might be associated with catabolite repression.
Assuntos
Desoxiglucose/farmacologia , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Acetatos/metabolismo , Saccharomyces cerevisiae/efeitos dos fármacos , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/metabolismo , Esporos Fúngicos/fisiologiaAssuntos
Mutagênese , Micologia/métodos , Saccharomyces cerevisiae/genética , Antibacterianos/farmacologia , Membrana Celular/metabolismo , Parede Celular/metabolismo , DNA Fúngico/efeitos dos fármacos , DNA Fúngico/genética , DNA Fúngico/efeitos da radiação , DNA Mitocondrial/genética , DNA Mitocondrial/efeitos da radiação , Resistência Microbiana a Medicamentos/genética , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Genes Fúngicos/efeitos dos fármacos , Genes Fúngicos/efeitos da radiação , Mutagênicos/farmacologia , Consumo de Oxigênio/genética , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/efeitos da radiação , TemperaturaAssuntos
Micologia/métodos , Saccharomyces cerevisiae/genética , Acriflavina/farmacologia , Fusão Celular/genética , DNA Fúngico/genética , DNA Mitocondrial/genética , Etídio/farmacologia , Técnicas de Transferência de Genes , Organelas/genética , Ploidias , Protoplastos , Reprodução/genética , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/fisiologiaRESUMO
An industrial strain of Saccharomyces cerevisiae was fused with an osmotolerant yeast, Debaryomyces hansenii, to obtain hybrids having increased tolerance to elevated salt concentrations. The hybrids were intermediate to parent species in production of ethanol and polyols.