Search results for "YEAST"
showing 10 items of 792 documents
The Influence of The Degree of Grinding to Obtain of Some Fermented Mashes Based on Whole Wheat and Husked Millet
2011
The purpose of this article was to study the influence of degree of milling whole wheat (was ground in 4 variants of grain) and husked millet (was finely ground) to obtain fermented mashes type Braga. There have been 4 mashes of grist of whole wheat, grist husked millet, hop pellets and water and were boiled under continuous stirring and then cooled. Their content has diluted with water and then strainer by pressed through a sieve. Each mash-filtrate has divided in two and added white sugar 7%, resulting two series of sweet mashes. One has inoculated with a mixed culture of yeast and lactic bacteria and the other only with yeast culture. After fermentation were analyzed fermented mashes (pH…
Degradation of vanillic acid and production of guaiacol by microorganisms isolated from cork samples
2003
The presence of guaiacol in cork stoppers is responsible for some cases of cork taint causing unpleasant alterations to wine. We have performed a characterization of the cork-associated microbiota by isolating 55 different microorganisms: eight yeast, 14 filamentous fungi or molds, 13 actinomycetes and 20 non-filamentous bacteria. A screening for degradation of vanillic acid and guaiacol production showed that none of the filamentous fungi could achieve any of these processes. By contrast, five of the eight yeast strains isolated were able to degrade vanillic acid, although it was not converted to guaiacol. Guaiacol production was only detected in four bacterial strains: one isolate of Baci…
Industrial production of dried yeast: plasma membrane as a survival indicator of air drying process
2011
International audience; Preservation of microorganisms by desiccationis a major industrial interest.However, study of cell survival mechanismsthat occur during desiccation is complex. In this work, the impact of the magnitude and the kinetics of dehydration on yeastsurvival wereevaluatedin either hyperosmotic liquid medium or a gaseous environment. Asame lethal magnitude of dehydration and a same lethal kinetic effect were found. As previously shown for osmotic stress, this work demonstrate that yeast survival after drying was also related to plasma membrane disorganization, suggesting a similar passive rearrangement of the membrane components.Hyperosmotic treatment in liquid medium represe…
Anhydrobiosis of yeast: changes of cell surface structures and non-conventional applications of anhydrobiosis
2014
Darba mērķis bija veikt pētījumus par anhidrobiozi jaunu teorētisku faktu atklāšanai un plašināt raugu anhidrobiozes praktisku izmantošanu. Atklāta atsevišķu šūnas sieniņas proteīnu un citoplazmatiskās membrānas transportieru nozīmīga loma raugu dzīvotspējas saglabāšanā anhidrobiozes stāvoklī. Parādīts, ka citoplazmatiskās membrānas transportiera Agt1 izmaiņas dehidratācijas/rehidratācijas laikā ir raugu celmu specifiskās. Izstrādāta jauna mikroorganismu immobilizācijas metode. Parādīta iegūto immobilizēto preparātu efektīvā izmantošana etanola ražošanā un notekūdeņu attīrīšanā, ka arī konstatēta šo preparātu augsta stabilitāte. Atzīmēts, ka immobilizācija ievērojami paaugstina šūnu reziste…
Mitochondrial inheritance and fermentative : oxidative balance in hybrids between Saccharomyces cerevisiae and Saccharomyces uvarum.
2008
Breeding between Saccharomyces species is a useful tool for obtaining improved wine yeast strains, combining fermentative features of parental species. In this work, 25 artificial Saccharomyces cerevisiae × Saccharomyces uvarum hybrids were constructed by spore conjugation. A multi-locus PCR‐restriction fragment length polymorphism (PCR‐RFLP) analysis, targeting six nuclear gene markers and the ribosomal region including the 5.8S rRNA gene and the two internal transcribed spacers, showed that the hybrid genome is the result of two chromosome sets, one coming from S. cerevisiae and the other from S. uvarum. Mitochondrial DNA (mtDNA) typing showed uniparental inheritance in all hybrids. Furth…
Mitochondria inheritance is a key factor for tolerance to dehydration in wine yeast production
2015
UNLABELLED Mitochondria are the cell's powerhouse when organisms are grown in the presence of oxygen. They are also the source of reactive oxygen species that cause damage to the biochemical components of the cell and lead to cellular ageing and death. Under winemaking conditions, Saccharomyces yeasts exclusively have a fermentative metabolism due to the high sugar content of grape must. However, their production as an active dry yeast (ADY) form required aerobic propagation and a dehydration process. In these industrial steps, oxidative stress is particularly harmful for the cell. In this work, we analysed the impact of the mitochondrial genome on oxidative stress response, longevity and d…
Mitotic Recombination and Genetic Changes in Saccharomyces cerevisiae during Wine Fermentation
2000
Natural strains of Saccharomyces cerevisiae are prototrophic homothallic yeasts that sporulate poorly, are often heterozygous, and may be aneuploid. This genomic constitution may confer selective advantages in some environments. Different mechanisms of recombination, such as meiosis or mitotic rearrangement of chromosomes, have been proposed for wine strains. We studied the stability of the URA3 locus of a URA3/ura3 wine yeast in consecutive grape must fermentations. ura3/ura3 homozygotes were detected at a rate of 1 x 10(-5) to 3 x 10(-5) per generation, and mitotic rearrangements for chromosomes VIII and XII appeared after 30 mitotic divisions. We used the karyotype as a meiotic marker an…
Effect of tin and lead chlorotriphenyl analogues on selected living cells.
2010
Three kinds of living cells, human embryonic kidney cells, Saccharomyces cerevisiae, and Escherichia coli, were tested for their sensitivity to chlorotriphenyltin and chlorotriphenyllead. The tin compound proved definitely more toxic than the lead derivative, particularly in the case of the human embryonic kidney cells devoid of any protective cell wall. Electron paramagnetic resonance (EPR) comparative studies carried out by using a natural model liposome system (egg yolk lecithin) confirmed considerable changes within the lipid bilayer upon doping by the aforementioned additives, which may be crucial to the mechanism of the observed cell cleavage. The individual dopants revealed diverse i…
The use of trypsin to solubilize wall proteins from Candida albicans led to the identification of chitinase 2 as an enzyme covalently linked to the y…
2002
The use of trypsin to break proteins covalently linked to the yeast walls of Candida albicans released approx. 50% of the proteins, but also glucose and N-acetylglucosamine. Analysis by affinity chromatography indicated that glucose and/or N-acetylglucosamine formed part of the same supramolecular complexes with mannoproteins. These complexes would represent a new type of cell wall structuration in which beta-1,6 glucan and chitin are linked to proteins. An internal peptide from a 50-kDa protein released by trypsin was sequenced, showing 100% identity with chitinase 2 protein and 92% with chitinase 3. The electrophoretic mobility of the chitinase 2 protein was changed by treatment with Endo…
Characterisation of the yeast Pichia membranifaciens and its possible use in the biological control of Botrytis cinerea, causing the grey mould disea…
2001
Pichia membranifaciens strain FY-101, isolated from grape skins, was found to be antagonistic to Botrytis cinerea, the causal organism of the grey mould disease of the grapevine. When grown together on solid as well as liquid media, the yeast brings about the inhibition of this parasitic fungus, coagulation and leakage of its cytoplasm, and suppression of its ability to produce the characteristic grey mould symptoms on the grapevine plantlets. In vitro experiments confirm that this yeast can be used as a biological control organism against B. cinerea. An account of the molecular characterisation of P. membranifaciens (complete sequence of the ITS region of its ribosomal DNA, GenBank accessi…