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Coal from the Highveld seam 4 deposit was studied to determine and understand the influence of density and particle size on the high temperature combustion characteristics. All of the charring, as well as the combustion experiments were conducted in a high temperature horizontal tube furnace where charring was done at 1100 °C and combustion at 1000 °C. The furnace was equipped with carbon monoxide and carbon dioxide analysers to monitor carbon conversion during experimentation. The parent coal was characterised in terms of proximate analysis, ultimate analysis, calorific value analysis and FTIR analysis. The chars were investigated with FTIR analysis. The coals were categorized according to density from +1.4 g.cm-3 to -2.0 g.cm-3 using 0.2 g.cm-3 intervals and the particle size effect was studied using particles of 20, 30 and 40 mm diameter. The characterization results showed that the moisture content of the coal samples tended to decrease as the particle density increased and that the smaller particles tended to have a higher moisture content. The volatile matter and fixed carbon content decreased as the coal density increased, while both had a relatively even distribution across the size ranges. The ash content was found to significantly increase as the density increased. Elemental analysis revealed that that carbon-, hydrogen- and nitrogen- content decreased as density increased with a relatively even distribution of the different size ranges. High sulphur values were observed in the high density particles. This was attributed to a higher pyrite content in this fraction. Smaller particles tended to have a higher oxygen content. Calorific value analysis showed that the high density fraction had a very low heating value and that the overall sample value would be improved by removing the high density fraction. FTIR analysis showed that the properties of density separated fractions varied significantly; this was most prominent in the substitution structures occurring on the aromatic structures. It was found that the chemical composition of the size separated particles remained relatively constant. The properties of char particles with different densities tended to become more similar, especially with regard to their aromatic substitution structures. The characterization of the different coal samples showed that the parameters were generally significantly different for the different density fractions but did not vary significantly across the particle size ranges. It was also found that significant shattering occurred at heating rates of 50 °C/min, while very little shattering was observed at 15 °C/min. The low density particles formed porous ash residues, while the high density particles formed very hard and solid ash residues that could contain unreacted carbon in the core. Combustion studies showed that particle density and size had a significant influence on the time required for complete conversion of the chars. The low density particles required less time for full conversion than the high density particles and the smaller particles reacted faster than the larger particles. Modelling of the experimental data showed that the shrinking unreacted core model can be used to describe the combustion characteristics of both the size and density separated particles. The controlling mechanism was found to be a combination of internal and external diffusion. From the modelling results it was found that effective ash layer diffusion became more prominent as the density increased and that the obtained mass transfer coefficients correlated well with values found in literature. Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2011

International audience; Saccharomyces cerevisiae metabolizes arginine, one of the major amino acids in grape musts, to ornithine and urea during wine fermentations. Wine yeast strains of S. cerevisiae do not fully metabolize urea during grape must fermentation. Urea is secreted by yeast cells and it reacts spontaneously with ethanol in wine to form ethyl carbamate, a potential carcinogenic agent for humans. The lack of urea catabolism by yeast in wine may be ascribed to the transcriptional repression of the DUR1,2 gene by good nitrogen sources present in the grape must. We expressed the DUR1,2 gene under control of the S. cerevisiae PGK1 promoter and terminator signals and integrated this DUR1,2 expression cassette, flanked by ura3 sequences, into the URA3-locus of the industrial wine yeast UC Davis 522. In vivo assays showed that the metabolically engineered industrial strain reduced ethyl carbamate in Chardonnay wine by 89.1%. Analyses of the genotype, phenotype, and transcriptome revealed that the engineered yeast 522EC- is substantially equivalent to the parental 522 strain.

Cider has experienced a rise in popularity in the province of Ontario. Industrial fermentation of dessert apples (Malus domestica Borkh.) by domesticated Saccharomyces wine yeast is the preferred production method of Ontario cideries. Here, four novel Saccharomyces yeasts were isolated and characterized based on their ability to ferment apple must. The fermentation kinetics of all four novel strains were also compared under five different nitrogen supplementation regimens. The isolates differed in their consumption of cider sugars although all successfully completed fermentations. Supplementing with amino acids or diammonium phosphate (DAP) caused an increase in must attenuation compared to no nitrogen addition. The addition of amino acids or DAP 72 hours into the fermentation enabled several isolates and industrial yeasts to increase the production of fruity-associated flavour compounds such as higher alcohols and esters. Overall, the findings provide Ontario cideries with new resources to sustain continued growth of the already burgeoning industry.

Brettanomyces bruxellensis is beginning to gain popularity in the craft brewing industry; however, a lack of research on this yeast and lengthy fermentation times present challenges for brewers. Here eight novel Brettanomyces strains were characterized and two were chosen for secondary and co-pitch fermentations, along with the industry standard BSI Drei. The ester and phenol content of these beers was slightly lower than that found in primary Brettanomyces fermentations. Regardless, mixed fermentations proved to be a viable approach to developing beers with "Brett character" in a shortened timeframe. It was also observed that ester and phenol synthesis peaked around day 14 and near the end of the fermentation, respectively. Furthermore, supplementation of thiamine or various amino acids to the pre-growth or fermentation appeared to have a positive effect on fermentation rate in a strain dependent manner. Overall, these findings will allow brewers to be better informed when developing products using Brettanomyces. OMAFRA-University of Guelph Research Program (Product development through value chains; UoG2016-2623); OMAFRA-University of Guelph Gryphons LAAIR (LAAIR2015-5142)

Traditional sparkling wines are the product of carbonation and aging of a base wine with yeast in the bottle, where yeast cell compounds are released over time which contribute to flavour and appearance. This often lengthy process is known as autolysis. Our lab identified several proteins related to autophagy that result in autolysis when overexpressed. Overexpression of autophagy-related genes ATG3 and ATG4 in industrial wine yeast was found to be a suitable strategy to accelerate cell death and autolysis of wine yeast during nitrogen starvation. We also found that that ATG3 and ATG4 overexpression has pleiotropic ramifications: reduced turnover of autophagic cargo, vacuolar fragmentation, abnormal accumulation of lipids, and accelerated generation of ROS, all of which precede cell death and likely contribute to the impaired response to nitrogen stress. These results work toward solving an important industrial problem, as well as furthering our understanding of autophagy regulation during starvation.

During aging of high quality sparkling wine, yeasts that have finished fermentation slowly die and release metabolites into the wine that are responsible for characteristic taste and foaming properties. Two of the main processes that aid in aging are autolysis and autophagy but their regulation during secondary fermentation remains largely unknown. Microarray analysis of the Saccharomyces cerevisiae strain DV10 during secondary fermentation yielded some potential targets for future studies regarding these processes. Several stress pathways were identified as well as the GATA transcription factors GAT2, GAT3, and GAT4. Many proposed targets of GATA transcription factors are part of the ATG family of autophagy genes, which had one or more copies of the GATA consensus sequence in their promoters. This possible relationship is of particular interest due to the poorly understood roles of these GATA factors and could lead to better understanding of the regulatory processes of autophagy.

An investigation was undertaken to determine the distribution of chemical-, petrographic- and mineralogical properties of large coal particles of different sizes and densities and to evaluate a suitable reaction rate model for combustion of corresponding chars. This was undertaken in order to contribute to the knowledge of the combustion kinetics of large particles in fluidized bed combustion and moving bed combustion/gasification. The study was confined to a mineral rich (24.1 wt%) and inertinite rich (74 wt%) parent coal (precursor) that was separated into different sizes and density fractions. The combustion reactive properties of chars prepared at 1100 °C and at a reaction temperature of 1000 °C were determined using a horizontal tubular furnace with the associated on-line analysers and temperature controllers. Coal particles in the size range of 0.50–53 mm diameter and density from 1.4 g cm−3 to 2.0 g cm−3 were studied. The characterisation of the different coal samples consisting of ash content, maceral content, fuel ratios and calorific values showed that the parameters did not vary significantly over the particle size ranges, but were different for the different density fractions. Combustion studies showed that particle size and density influenced the time required for complete conversion of the chars. The smaller particles and low density particles reacted faster and the modeling of the experimental data showed that the isothermal shrinking un-reacted core model with film and ash layer diffusion was applicable. The effective ash layer diffusion becomes more prominent as the density increased and the mass transfer coefficients correlated well with published results National Research Foundation, South Africa

The wine yeast Saccharomyces cerevisiae experiences a range of stress conditions during wine fermentation. These stresses include osmotic stress, hypoxia, nutrient starvation, cold stress and increasing ethanol stress as fermentable sugars are converted to ethanol. These various stresses affect the functionality of the plasma membrane, cell wall and subsequently the yeast’s efficiency during fermentation. Etp1, a poorly characterized protein has been shown to have several different fermentation related phenotypes; it is needed for the turnover of the hexose transporter Hxt3 upon a shift from glucose to ethanol, and the transcriptional activation of the stress response genes HSP12 and HSP26 under ethanol stress. The molecular function of Etp1 during fermentation is not understood. This research aims to understand the molecular mechanism of Etp1 function and its involvement in Chardonnay fermentation using the S. cerevisiae M2 wine yeast strain. OMAFRA, Genome Canada

Saccharomyces cerevisiae are unicellular organisms that are highly adaptable to acute changes in nutrient availability. The two main signaling pathways that allow S. cerevisiae to sense and respond to changes in glucose availability in the environment are the conserved cAMP/PKA and AMPK/Snf1 kinase-dependent pathways. The conserved TORC1 pathway is primarily responsible for allowing cells to respond to the availability of nitrogen. Studies have shown that S. cerevisiae, but not mammalian and plant cells, regulate nuclear tRNA trafficking in response to nutrient stress. Here, we show that the yeast species of the Saccharomyces genus, but not Schizosaccharomyces pombe and Kluyveromyces lactis specifically regulate nuclear tRNA export in response to nutrient stress, providing further evidence that regulation of nuclear tRNA export in response to nutrient availability is not evolutionarily conserved. We also established that amino acid and nitrogen starvation affects nuclear export of a subset of tRNAs in S. cerevisiae. Inhibition of TORC1 signaling by rapamycin treatment, which simulates nitrogen starvation, also affects nuclear export of the same subset of tRNAs, suggesting that the TORC1 signaling pathway plays a role in regulating nuclear export of the tRNAs in response to nitrogen level. Regulation of nuclear export of these tRNAs by nitrogen deprivation is most likely due to an effect on the function of the nuclear tRNA export receptors, as overexpression of the tRNA export receptor, Los1p, restores export of the tRNAs during nitrogen starvation. These findings suggest that the TORC1 signaling pathway may, in part, regulate nuclear export of the tRNAs by affecting the function of the tRNA export receptors. In contrast to amino acid and nitrogen starvation, glucose depletion affects nuclear export of all tRNA species in S. cerevisiae. Evidence obtained suggests that nuclear retention of tRNA in cells deprived of glucose is due to a block in nuclear re-import of the nuclear tRNA export receptors. Retention of the receptors in the cytoplasm is not caused by activation of Snf1p, but by the inactivation of PKA during glucose deprivation. Furthermore, regulation of nuclear re-import of the receptors is not due to phosphorylation of the tRNA export receptors by PKA. However, PKA phosphorylates known components of the tRNA export machinery. A model that is consistent with the data is that PKA and an unknown mechanism regulate the activity of these components or an unidentified protein(s) to control nuclear re-import of the receptors in response to glucose availability.

The pdf file contains numerous hyperlinks and bookmarks to facilitate navigation. This thesis will be of interest to those working with topics such as data mining of microarray data, novel gene function discovery and prediction, and genome-wide responses to fermentation stresses. High throughput technologies such as microarrays and modern genome sequencers produce enormous amounts of data that require novel data processing. This thesis proposes a method called Interdependent Correlation Cluster (ICC) to analyze the relations between genes represented by microarray data that are conditioned on a specific target gene. Based on Correlation Clustering, the proposed method analyzes a large set of correlation values related to the gene expression profiles extracted from given microarray datasets. The proposed method works on any size microarray datasets and could be applied to any target gene. In this study the selected target gene, NSF1 /USV1 / YPL230W, encodes a poorly characterized C2H2 zinc finger transcription factor (TF) involved in stress responses in yeast. The method is successful in the identification of novel NSF1 functional roles during fermentation stress conditions in the M2 industrial yeast strain. The new identified functions include regulation of energy and sulfur metabolism, protein synthesis, ribosomal assembly and protein trafficking as well as other processes. NSF1 involvement in sulfur metabolism was experimentally confirmed using biological laboratory techniques. Importantly, implication of NSF1 in sulfur metabolism regulation has highly relevant implications to wine and beer production industries concerned with production of compounds having sulfur-like off odour (SLO) and toxic properties. The correlation clustering also provides a means of understanding complex interactions existing between genes. Ministry of Training, Colleges and Universities of Ontario (Ontario Graduate Scholarship and Ontario Graduate Scholarships in Science and Technology); The Natural Sciences and Engineering Research Council of Canada (NSERC)

Maintaining intracellular ion homeostasis is crucial for cellular survival and function. In the yeast 'Saccharomyces cerevisiae', exposure to high NaCl concentrations results in an accumulation of Na+ ions intracellularly leading to a disruption in ion homeostasis. To combat this accumulation of Na+ ions the yeast activates the transcription of the gene 'ENA1' encoding a Na+-ATPase that extrudes Na+ ions from the cell. The protein Nha1p is also required to extrude Na+ ions out of the cell. Research presented in this thesis indicates that components of the Vid30c protein complex play an important role in the yeast's tolerance to NaCl stress with Vid28p playing a more central and dominant role. The 'VID28' and' VID24' genes are required for growth during exposure to high concentrations of NaCl. Many components that are a part of or are linked to the Vid30c are required for the NaCl induced activation of the 'ENA1' promoter with Vid28p being of particular importance. Down-regulation of the ' ENA1' promoter in the 'vid28'[Delta] mutant is due to improper activation of 'ENA1' transcription most likely through Crz1p. In addition, components of the Vid30c are also required to regulate the intracellular levels of Na+ and K+ ions during sodium stress, however this is unlikely due to the regulation of Nha1p. This thesis presents novel functions of components of the Vid30c that are required for the yeast to adapt to NaCl stress.