Improvement of Nitrogen Assimilation and Fermentation Kinetics under Enological Conditions by Derepression of Alternative Nitrogen-Assimilatory Pathways in an IndustrialSaccharomyces cerevisiaeStrain
Sie können Bookmarks mittels Listen verwalten, loggen Sie sich dafür bitte in Ihr SLUB Benutzerkonto ein.
Medientyp:
E-Artikel
Titel:
Improvement of Nitrogen Assimilation and Fermentation Kinetics under Enological Conditions by Derepression of Alternative Nitrogen-Assimilatory Pathways in an IndustrialSaccharomyces cerevisiaeStrain
Beteiligte:
Salmon, Jean-Michel;
Barre, Pierre
Erschienen:
American Society for Microbiology, 1998
Erschienen in:Applied and Environmental Microbiology
Beschreibung:
<jats:title>ABSTRACT</jats:title><jats:p>Metabolism of nitrogen compounds by yeasts affects the efficiency of wine fermentation. Ammonium ions, normally present in grape musts, reduce catabolic enzyme levels and transport activities for nonpreferred nitrogen sources. This nitrogen catabolite repression severely impairs the utilization of proline and arginine, both common nitrogen sources in grape juice that require the proline utilization pathway for their assimilation. We attempted to improve fermentation performance by genetic alteration of the regulation of nitrogen-assimilatory pathways in<jats:italic>Saccharomyces cerevisiae</jats:italic>. One mutant carrying a recessive allele of<jats:italic>ure2</jats:italic>was isolated from an industrial<jats:italic>S. cerevisiae</jats:italic>strain. This mutation strongly deregulated the proline utilization pathway. Fermentation kinetics of this mutant were studied under enological conditions on simulated standard grape juices with various nitrogen levels. Mutant strains produced more biomass and exhibited a higher maximum CO<jats:sub>2</jats:sub>production rate than the wild type. These differences were primarily due to the derepression of amino acid utilization pathways. When low amounts of dissolved oxygen were added, the mutants could assimilate proline. Biomass yield and fermentation rate were consequently increased, and the duration of the fermentation was substantially shortened.<jats:italic>S. cerevisiae</jats:italic>strains lacking URE2 function could improve alcoholic fermentation of natural media where proline and other poorly assimilated amino acids are the major potential nitrogen source, as is the case for most fruit juices and grape musts.</jats:p>