The fuel ethanol industry is now making use of a very efficient process where virtually all sugar substrates are converted to ethanol. Nevertheless, some metabolic by-products excreted from Saccharomyces cerevisiae tend to reduce the ethanol yield. Of such, glycerol is the major one, accounting for about 5-10% relative to the amount of ethanol produced. / Glycerol plays an important role in maintaining the redox balance within the cells by oxidizing the cytosolic NADH under anaerobic conditions. It is also believed that it acts as an osmoprotectant and would be favourably produced in high osmotic pressure conditions. / In order to mitigate the production of glycerol, various aeration strategies were investigated in a single-stage continuous fermentation system. Oxygen dissolved in the fermentation medium put the yeast in aerobiosis, acted as an oxidizing agent and hence minimised the specific glycerol production by 36% as compared to a completely anaerobic fermentation. / This has hardly been reproduced in a more industrially relevant system using a multi-stage continuous fermentation process. Indeed, oscillations in the concentrations of the various metabolites over time made difficult the assessment of significant changes. Nevertheless, these findings open the door to further investigations in order to understand the effect of oxygen in continuous fermentations using very high gravity feeds, such as in the fuel ethanol industry.

This thesis is concerned with cellular responses to stress including the adaptive response to H2O2, and the cellular roles of sumoylation in stress responses. 286 H2O2-sensitive Saccharomyces cerevisiae deletion mutants were screened and YAP1, SKN7, GAL11, RPE1, TKL1, IDP1 were identified to be important for adaptation to H2O2. The mutants fell into two groups based on their responses to acute and chronic doses of H2O2. Transcription factors Yap1p, Skn7p and Gal11p were important for both acute and chronic responses to H2O2. Yap1p and Skn7p were needed for up-regulation of anti-oxidant functions rather than generation of NADPH or glutathione. Adaptation was reduced in strains deleted for GPX3 and YBP1, which are involved in sensing H2O2 and activating Yap1p, but to a lesser extent than YAP1 deletion. RPE1, TKL1 and IDP1 deletants affected in NADPH production were chronically sensitive to H2O2, but resistant to an acute dose and other mutants affected in NADPH generation were also affected in adaptation. These mutants overproduced reduced glutathione (GSH) but maintained normal cellular redox homeostasis. Over-production of GSH was not regulated by transcription of the gene encoding -glutamylcysteine-synthetase. The Skn7p transcription factor is therefore important for the adaptive response to oxidative stress-induced by H2O2, and NADPH generation is also required for adaptation. The roles of sumoylation in stress responses and transcriptional regulation were examined by deleting the SUMO ligases Siz1p and Siz2p. Siz1p is required for tolerance to copper ions and DNA damage repair. Siz2p is involved in repression of stress responses, particularly oxidative stress and is required for activation of nucleotide and RNA metabolism, DNA processing and cell division. Both Siz1p and Siz2p act in parallel in the repressing heat-shock responses and in reducing chronological life span. Genome-wide transcriptional analysis showed that Siz1p and Siz2p repress the mitochondrial retrograde pathway and arginine biosynthesis, while activating some carbon and nitrogen metabolism genes. Sumoylation of proteins in the wild type was induced by nitrogen starvation or mitochondrial inhibition during the initial treatment. However, nitrogen starvation led to some protein degradation, while the SUMO-conjugated proteins were recycled in cells with disrupted mitochondrial functions.

Bibliography: leaves 182-190. / xv, 190 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Develops a suitable approach to determining the fundamental cell-wall mechanical properties of single biological cells, by combining the single-cell compression experiment with a mechanical model to determine the cell-wall mechanical properties of the yeast Saccharomyces cerevisiae / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1999

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Mannoproteins released during the fermentation of Saccharomyces cerevisiae in a chemically defined synthetic grape juice medium were isolated by ethanol precipitation. The proteins from the medium were fractionated by ion exchange chromatography. Fractions containing mannoproteins were identified by their UV absorption spectra and by the presence of polymeric mannose. A mannoprotein designated HPF2 was purified from one of the fractions by gel permeation chromatography, and had a high capacity to reduce heat-induced protein haze formation in white wine. After electrophoretic separation and transfer to nitrocellulose, HPF2 stained positively with an antibody (anti-HPFl) which had been raised against a previously isolated mannoprotein with known haze protective activity designated HPFL. Analysis of the carbohydrate portion of HPF2 using methylation analysis confirmed the presence of (1 -> 2), (1 -> 3) and (1 -> 2,1 -> 6) mannosyl residues and showed that it contained N-linked and possibly O-linked carbohydrate. Digestion of the mannoprotein with PNGase F resulted in a reduction in molecular weight, as measured by SDS-PAOE and confirmed the presence of N-linked carbohydrate. N-linked deglycosylation decreased the ability of HPF2 to protect wine from heatinduced protein haze. Protein sequence analysis of the peptides derived from the HPF2 mannoprotein obtained via digestion with endoproteinase Lys C led to the identification of the HPF2 structural gene in Saccharomyces cerevisiae followed by searching the Yeast Proteome Database for related sequences. Analysis of the deduced amino acid sequence of HPF2 from its structural gene indicated that HPF2 possessed a secretion signal at the NH₂-terminus, a putative OPI anchor site at the COOH-terminus and also contained serine and threonine rich regions at both the NH₂-terminus and COOHterminus. These regions may contain O-linked carbohydrate. There were also 15 potential glycosylation sites, five of which were classified from the peptide mapping data as likely glycosylation sites. These characteristics, combined with the results from the carbohydrate analysis, indicate that HPF2 was a mannoprotein derived from the yeast cell walls. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=678380 / Thesis (Ph.D.) -- University of Adelaide, Dept. of Plant Science, 2000

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Mannoproteins released during the fermentation of Saccharomyces cerevisiae in a chemically defined synthetic grape juice medium were isolated by ethanol precipitation. The proteins from the medium were fractionated by ion exchange chromatography. Fractions containing mannoproteins were identified by their UV absorption spectra and by the presence of polymeric mannose. A mannoprotein designated HPF2 was purified from one of the fractions by gel permeation chromatography, and had a high capacity to reduce heat-induced protein haze formation in white wine. After electrophoretic separation and transfer to nitrocellulose, HPF2 stained positively with an antibody (anti-HPFl) which had been raised against a previously isolated mannoprotein with known haze protective activity designated HPFL. Analysis of the carbohydrate portion of HPF2 using methylation analysis confirmed the presence of (1 -> 2), (1 -> 3) and (1 -> 2,1 -> 6) mannosyl residues and showed that it contained N-linked and possibly O-linked carbohydrate. Digestion of the mannoprotein with PNGase F resulted in a reduction in molecular weight, as measured by SDS-PAOE and confirmed the presence of N-linked carbohydrate. N-linked deglycosylation decreased the ability of HPF2 to protect wine from heatinduced protein haze. Protein sequence analysis of the peptides derived from the HPF2 mannoprotein obtained via digestion with endoproteinase Lys C led to the identification of the HPF2 structural gene in Saccharomyces cerevisiae followed by searching the Yeast Proteome Database for related sequences. Analysis of the deduced amino acid sequence of HPF2 from its structural gene indicated that HPF2 possessed a secretion signal at the NH₂-terminus, a putative OPI anchor site at the COOH-terminus and also contained serine and threonine rich regions at both the NH₂-terminus and COOHterminus. These regions may contain O-linked carbohydrate. There were also 15 potential glycosylation sites, five of which were classified from the peptide mapping data as likely glycosylation sites. These characteristics, combined with the results from the carbohydrate analysis, indicate that HPF2 was a mannoprotein derived from the yeast cell walls. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=678380 / Thesis (Ph.D.) -- University of Adelaide, Dept. of Plant Science, 2000

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Mannoproteins released during the fermentation of Saccharomyces cerevisiae in a chemically defined synthetic grape juice medium were isolated by ethanol precipitation. The proteins from the medium were fractionated by ion exchange chromatography. Fractions containing mannoproteins were identified by their UV absorption spectra and by the presence of polymeric mannose. A mannoprotein designated HPF2 was purified from one of the fractions by gel permeation chromatography, and had a high capacity to reduce heat-induced protein haze formation in white wine. After electrophoretic separation and transfer to nitrocellulose, HPF2 stained positively with an antibody (anti-HPFl) which had been raised against a previously isolated mannoprotein with known haze protective activity designated HPFL. Analysis of the carbohydrate portion of HPF2 using methylation analysis confirmed the presence of (1 -> 2), (1 -> 3) and (1 -> 2,1 -> 6) mannosyl residues and showed that it contained N-linked and possibly O-linked carbohydrate. Digestion of the mannoprotein with PNGase F resulted in a reduction in molecular weight, as measured by SDS-PAOE and confirmed the presence of N-linked carbohydrate. N-linked deglycosylation decreased the ability of HPF2 to protect wine from heatinduced protein haze. Protein sequence analysis of the peptides derived from the HPF2 mannoprotein obtained via digestion with endoproteinase Lys C led to the identification of the HPF2 structural gene in Saccharomyces cerevisiae followed by searching the Yeast Proteome Database for related sequences. Analysis of the deduced amino acid sequence of HPF2 from its structural gene indicated that HPF2 possessed a secretion signal at the NH₂-terminus, a putative OPI anchor site at the COOH-terminus and also contained serine and threonine rich regions at both the NH₂-terminus and COOHterminus. These regions may contain O-linked carbohydrate. There were also 15 potential glycosylation sites, five of which were classified from the peptide mapping data as likely glycosylation sites. These characteristics, combined with the results from the carbohydrate analysis, indicate that HPF2 was a mannoprotein derived from the yeast cell walls. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=678380 / Thesis (Ph.D.) -- University of Adelaide, Dept. of Plant Science, 2000

Thesis (M.Sc.)--York University, 2006. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 118-125). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR19667

Thesis (Ph. D.)--School of Biological Sciences. University of Missouri--Kansas City, 2007. / "A dissertation in cell biology and biophysics and molecular biology and biochemistry." Advisor: Antony A. Cooper. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 7, 2008 Includes bibliographical references (leaves 100-134). Online version of the print edition.

Proefschrift Universiteit van Amsterdam. / Auteursnaam op omslag: Léonie Raamsdonk. Met bibliogr., lit. opg. - Met samenvatting in het Nederlands.

Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.