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1

Enantioselective bioreduction of propentofylline using yeast in water and organic solvents

100%
Pekala E., Latacz G., WojciK T.
|
2007
|
issue 2
174-180
EN
Propentofylline (PPT) is a drug used in the treatment of both vascular dementia and Alzheimer type dementia. Hydroxy-metabolites of propentofylline (OHPPT) also demonstrate the same biological activity as the parent compound. As steroisomers of HOPPT are not commercially available, we had to produce them for pharmacological and pharmacokinetic studies. The aim of this study was to find the strains of Saccharomyces cerevisiae yielding enantiomerically pure (R)- or (S)-1-(5-hydroxyhexyl)-3,5-dimethyl-7-propylxanthin (OHPPT) from PPT. In this paper, we present the results of stereoselective reduction of PPT into OHPPT when catalysed by whole cells of baker's and a few strains of wine yeast in water and organic solvents.
2

Classic techniques for improvement of industrial yeast strains. Part II ? Transmission of killer activity into laboratory and industrial strains of Saccharomyces cerevisiae by electrotransformation

100%
Salek A. T.
Biotechnologia
|
2002
|
issue 1
175-186
EN
Killer-sensitive strains of Saccharamocyces cerevisiae and Saccharomyces uvarum var. carlsbergensis were transformed by electroinjection using dsRNA isolated from a superkiller strain. Various recipient strains were used: both thermo-resistant and thermo-sensitive as well as mutants of industrial strains. Conversion of respiratory competent (rho+) into respiratory deficient (rho-) strains (mutants) resulted in a significant increase in the yield of electrotransformants and/or of long-term killer stability. Electrotransformation of rho- mutants of distillery and brewery strains resulted in more than 100 clones, which exhibited weak or strong killer activity over some or all of the experimental period of 10 months.
3

Classic techniques for improvement of industrial yeast strains: Part III ? A method for enucleation of Saccharomyces sp.

100%
Salek A. T.
Biotechnologia
|
2002
|
issue 1
187-194
EN
The first method for enucleation of yeast Saccharomyces cerevisiae is reported. Various strains, including some killer strain and respiratory-deficient mutants of Saccharomyces cerevisiae were enucleated after treatment with cytochalasin B. Removal of nuclei from protruding sphaeroplasts was induced by centrifugation in a Percoll density gradient. The enucleation yield (which averaged about 80%) and the quality of the cytoplasts were best when the yeast culture had been synchronized with nocodazole before the preparation. The presence of 1 mM CaCl2 and ATP (10 muM) in the enucleation medium prevented the formation of fragile products or aggregation. Cytoplasts could be stored for at least 1 day without visible deterioration.
4

Heterologus gene expression in S.cerevisiae

100%
Topczewska J.
Biotechnologia
|
1993
|
issue 3
184-195
EN
Yeast S.cerevisiae plays an important role of a host for expression and . High-level expression of foreign genes in S. cerevisiae is the result of a number of optimized reactions in the cell. In this article I will focus on the vectors designed for efficient expression and secretion of foreign proteins from yeast cells into the medium.
5

The comparison of praziquantel biotransformation in silico and in vitro

100%
Godawska A., Pekala E., Kiec-Kononowicz K.
Biotechnologia
|
2005
|
issue 1
215-222
EN
Praziquantel (PZQ) is a drug which is used by choice to schistosomiasis treatment. Currently, it is used in malaria treatment. PZQ undergoes extensive metabolism in human body, mainly in liver, by two cytochrome P-450 isoenzymes 2B1 and 3A. As a result of these biotransformations, numerous mono- and dihydroxylated derivates in B, C and D rings are formed. Only one metabolite has been identified and described, it is 4-hydroxypraziquantel (4-OH-PZQ). So for, the metabolites out of PZQ biotransformation were obtained under the influence of Cunnighamelle echinulata and Beauveria bassiana. There were the derivatives in position C7 and in D-ring (position is unknown). In our research, we would like to create a new model of PZQ biotransformation in vitro. For such purpose, Saccharomyces cerevisiae were used. The results of PZQ biotransformation in vitro under the influence of Saccharomyces cerevisiae were compared with computer simulation of PZQ metabolism performed by the use of Metabol Expert program.
6

Bioconversion of lignocallulosic materails

100%
Targonski Z.
Biotechnologia
|
1996
|
issue 3
116-130
EN
The degradation of lignocellulose to provide fuels and chemicals is a subject of intensive investigation.THis paper cutlines the current biotechnological methods and discisses the problems of cellulose and hemicellulose bioconversion to ethanol.The relationships between physical and chemical properties of lignocellulose and enzymatic hydrolysis are shown.The applications of genetic engineering to Trichoderma resei, Saccharomyces cerevisiae and other organisma increase the yield of ethanol from lignocellulosics material is described.
7

Growth and fermentative activities of yeasts Saccharomyces cerevisiae in the presence of killer toxin

100%
Drewicz E., Kregiel D., Oberman H.
Biotechnologia
|
1999
|
issue 2
25-37
EN
Killer yeasts or killer resistant yeasts can be used as starter cultures in fermentative industries to prevent the environments from contamination by wild yeasts. The aim of the work was to investigate the effect of killer yeasts of Saccharomyces cerevisiae T158C, producer of K1 killer toxin, on the wine yeasts Saccharomyces cerevisiae W11, producer of K2 killer toxin, and W6 strain which was sensitive to both toxins. Wine yeasts W6 and killer wine yeats W11 showed different survival rates and fermentative activity in the presence of killer toxin K1 secreted by T158C strain. Obtained results showed that killer yeasts may be usefull when the fermentative conditions (temperature, pH value) will be suitable the activity of killer toxins.
8

Malic acid metabolism by yeasts Schizosaccharomyces and Saccharomyces

100%
Kunicka A., Szopa J. S.
Biotechnologia
|
1996
|
issue 1
151-161
EN
The importance of malic acid degradation by yeasts during winemaking is pointed and metabolic pathways for maloalkoholic fermentation by Schizosaccharomyces and Saccharomyces and malate transport system are summarized.Due to methods both of classical genetics and genetic engineering new strains for industrial fermentation, which may utilize L-malic acid, can be developed.Yeasts cells are also considered good hosts for cloning the bacterial gene resposible for malolactic fermentation originated from Lactobacillus and Lactococcus.
9

Classic techniques for improvement of industrial yeast strains. Part I? Construction of ethanol-resistant and osmophilic industrial strains of Saccharomyces cerevisiae by electrofusion

100%
Salek A. T.
Biotechnologia
|
2002
|
issue 1
153-174
EN
The effective production of biomass or ethanol in industrial media of high osmolality requires new yeast strains. The present work focused on the development of such strains. Genetic engineering methods using cytoplasmatically-marked yeast (electrofusion of protoplasts of heterothallic haploids; electrotransformation of killer dsRNA or VLPs into haploids; generation of rho-) were used. The characteristics of the hybrids were evaluated by conventional analytical and instrumental methods, followed by statistical interpretation. After screening for a minimum 10% increase in industrially-relevant parameters, 3 osmophilic hybrids of baker's yeast, as well as 8 improved strains of distillery yeasts were selected. The baker?s yeasts showed optimum growth in a relatively concentrated molasses wort (1:5 ratio of molasses to final volume). The alcohol-resistant yeasts (including killer) produced up to 14.5% (w/w) ethanol in a medium containing 34% dissolved solids (a mixed mash of sucrose and potato). The characteristics of the alcohol-resistant and osmophilic yeasts were stable over several years of their industrial applications.The results show that electrical techniques (fusion to obtain hybrids, with interpretation by computer-aided image analysis, and transformation to give marked strains) can be used effectively enough for the construction of some industrially-productive yeasts.
10

Attempts to transform the killer factor of yeasts Saccharomyces cerevisiae to amylotytic yeasts Schwanniomyces occidentalis

88%
Stobinska H., Drewicz E., Kregiel D., Oberman H.
Biotechnologia
|
1997
|
issue 1
158-166
EN
The fermentation yeasts Saccharomyces cerevisiae capable of producing killer factor type K2 and amylolytic yeasts Schwanniomyces occidentalis were used to obtain the somatic hybrids by means of fusion protoplasts according to Fournier.The obtained hybrids showed amylolytic and fermentation activity.They also were characterized by the ability to form spores and to biosynthesize the killer factor.Their stability was dependent on the composition of the cultivation medium.
11

Genome-wide identification of genes involved in tolerance to various environmental stresses in Saccharomyces cerevisiae

88%
Auesukaree C., Damnernsawad A., Kruatrachue M., Pokethitiyook P., Boonchird C., Kaneko Y., Harashima S.
Journal of Applied Genetics
|
2009
|
vol. 50
|
issue 3
301-310
EN
During fermentation, yeast cells are exposed to a number of stresses ? such as high alcohol concentration, high osmotic pressure, and temperature fluctuation ? so some overlap of mechanisms involved in the response to these stresses has been suggested. To identify the genes required for tolerance to alcohol (ethanol, methanol, and 1-propanol), heat, osmotic stress, and oxidative stress, we performed genome-wide screening by using 4828 yeast deletion mutants. Our screens identified 95, 54, 125, 178, 42, and 30 deletion mutants sensitive to ethanol, methanol, 1-propanol, heat, NaCl, and H2O2, respectively. These deleted genes were then classified based on their cellular functions, and cross-sensitivities between stresses were determined. A large number of genes involved in vacuolar H+-ATPase (V-ATPase) function, cytoskeleton biogenesis, and cell wall integrity, were required for tolerance to alcohol, suggesting their protective role against alcohol stress. Our results revealed a partial overlap between genes required for alcohol tolerance and those required for thermotolerance. Genes involved in cell wall integrity and the actin cytoskeleton are required for both alcohol tolerance and thermotolerance, whereas the RNA polymerase II mediator complex seems to be specific to heat tolerance. However, no significant overlap of genes required for osmotic stress and oxidative stress with those required for other stresses was observed. Interestingly, although mitochondrial function is likely involved in tolerance to several stresses, it was found to be less important for thermotolerance. The genes identified in this study should be helpful for future research into the molecular mechanisms of stress response.
12

Using respiratory deficient mutants of Saccharomyces cerevisiae to glucose and xylose cofermentation with Pichia stipitis

88%
Kordowska-Wiatr M., Targonski Z.
Biotechnologia
|
1997
|
issue 4
94-102
EN
One of the main problems limiting the economic production of ethanol from lignocellulosic biomass is D-xylose fermentation. In a medium containing glucose and xylose, it is preferable to achieve conversion with glucose fermenting yeast like S. cerevisiae and xylose fermenting yeast like P. stipitis. In order to resolve this problem, it is better to use respiratory deficient mutants. In this research, respiratory deficient mutant strains S. cerevisiae V30 and Ja(a) were obtained and their ability to ferment glucose in coculture with P. stipitis was investigated. A higher xylose conversion was observed in P. stipitis cultivation with these mutants because of better oxygen conditions than in the culture with native S. cerevisiae. A degree of assimilated xylose did not efficiently increased ethanol yields but on the other hand it increased the production of yeast biomass. Process considerations in relation to the fermentative performances using different strains combinations are discussed.
13

Presence and significance of the infectious elements in technologically relevant yeasts' cells

75%
Dzwonek M., Gniewosz M., Primik M., Duszkiewicz-Reinhard W.
Biotechnologia
|
2005
|
issue 3
202-208
EN
The killer phenotype of Saccharomyces cerevisiae strains is based upon the presence of viruses in the cytoplasm of the yeast cells. Resent analysis of the molecular basis in these phenomenon let researchers to reveal its molecular mechanism and ecological function. Mammalian transmissible spongiform encephalopathiesare is likely due to the propagation of an abnormal form of some protein. Such infectious agents, which are termed prions, exist in yeasts. This review highlights the variety of infectious elements present in Saccharomyces cerevisiae as well as their influence on the yeasts properties.
14

Is there any mystery of ORPHANs ?

75%
Cebrat S., Dudek M., Mackiewicz P.
|
|
vol. 38
|
issue 4
365-372
EN
We have analysed the coding capacity of ORFs longer than 100 codons found in the yeast genome. Comparing the parameters describing the DNA asymmetry in the set of known genes and the set of all ORFs>100 codons we have found that there are about 4700 coding ORFs in the yeast genome. Since for more than 2300 ORFs recognisable functions have been already found and for about 2000 ORFs homology to known genes has been identified - only about 400 ORFs can be considered as orphans - ORFs without any known function or homology. This finding means that there is no mystery of orphans - a paradox showing that the fraction of orphans has been growing with the growing number of genes with known functions in the yeast genome.
15

The influence of environmental stresses on Saccharomyces cerevisiae yeast in ethanol fermentation

75%
Grajek W., Szymanowska D.
Biotechnologia
|
2008
|
issue 3
46-63
EN
The development of ethanol fermentation process brings numerous environmental stresses influenced by the survival and metabolism of industrial microorganisms. Saccharomyces cerevisiae strains have evolved to survive constant fluctuation in their external surroundings by special adaptation systems. These adaptation mechanisms involve reorganization of genomic expression by activation of transcriptional factors under stress conditions and production of suitable metabolites increased by cell survival. This review is focused on the metabolism and genetic response of cells to diverse environmental changes, especially to heat, osmotic, ethanol, oxidative, toxic and other physic-chemical stresses.
16

The yeast Saccharomyces cerevisiae in science and biotechnology

75%
Ulaszewski S.
Biotechnologia
|
1994
|
issue 1
17-31
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