Reductive sulfate assimilation, the biological process by which sulfur-containing amino acids and key derivatives are synthesized from sulfate, is broadly shared among bacteria, fungi, and plants. It is the major, if not sole source of methionine and cysteine for Saccharomyces cerevisiae during wine fermentation. Two obligate intermediates formed in the...
Nutritional shift-up experiments have revealed many important
macromolecular interactions in bacteria. It has been shown that RNA
synthesis can be dissociated from protein and DNA synthesis. The
rates of protein synthesis were found to be, at a given temperature,
strictly dependent on the numbers of mature ribosomes present.
DNA synthesis...
The catabolism of glucose by proliferating and resting cells of
two strains of Saccharomyces cerevisiae has been examined, with
respect to the nature and participation of concurrent glucose pathways
by means of the radiorespirometric method. The nicotinamide
nucleotide content, and nicotinamide nucleotide oxidase activities
in these cells were also examined....
The inhibitory effect of 2-deoxy-D-glucose (2-DG) upon the
metabolism of glucose and fructose by proliferating cells of
Saccharomyces cerevisiae (OSU strain 2) has been examined. By
the use of radiotracer methods, particularly radiorespirometric
techniques, it has been possible to demonstrate that the rate of
hexose assimilation by yeast cells is...
Existing methods for the estimation of relative participation of
glucose catabolic pathways make use of yield data of respiratory
¹⁴CO₂ or intermediary ¹⁴C products derived from glucose substrates
specifically labeled with ¹⁴C. Cumulative yields of respiratory
¹⁴CO₂ observed at the end of time course of complete substrate
utilization are analyzed...
An assay is described to measure sterol uptake in
Saccharomyces cerevisiae. This assay involves specific
binding of radioactively labelled sterol to actively
growing yeast cells.
It was found that uptake does not occur in stationary
cultures and that some growth is necessary for FY3 , a
sterol auxotroph, to take...
The positions of the DNase I hypersensitive sites within the
galactose gene cluster of the yeast Saccharomyces cerevisiaa have
been determined. When yeast nuclei were incubated with DNase I, the
purified DNA restriction endonuclease digested and analyzed by
Southern hybridization, five hypersensitive regions were observed in
this cluster of three...
The role of the yeast S-adenosylmethionine: Δ²⁴-sterol-C-methyltransferase
(SCMT) in sterol metabolism was investigated.
Structural analogs of S-adenosylhomocysteine were tested for
inhibition of the SCMT enzyme. A wide inhibitory range by these
compounds was observed, indicating which structural features of the
parent compound are important for binding to the enzyme. The...
I examined, in three separate studies, the active chromatin
structure of the yeast, Saccharomyces cerevisiae.
Yeast contains four proteins having amino acid compositions
typical of the high mobility group (HMG) proteins. Three of these
are eluted from chromatin by 0.35 M NaCl; one is not, but is eluted
by 0.25...
The efficiency of cellulose hydrolysis under straight saccharification and simultaneous saccharification and fermentation (SSF) conditions was evaluated using three lignocellulosic materials (switchgrass, cornstover, and poplar), which had been pretreated with dilute sulfuric acid under conditions which optimized xylose concentrations in the prehydrolysate liquid. Yields of glucose, cellobiose and ethanol obtained...
Sulfite mutants representing five complementation groups, previously derived from
an ethyl methanesulfonate-treated haploid strain of Saccharomyces cerevisiae were studied.
Although the wildtype S. cerevisiae strain used (isogenic to X2180-1 A) had a basal
tolerance for sulfite (7 μM free H₂SO₃), the sensitive and resistant mutants were found to
tolerate less...
A major challenge in ethanol production using lignocellulosic feed stock is
inefficient utilization of hemicellulose, which accounts for 30-40% of lignocellulosic
biomass. Xylose, comprising >60% of recoverable sugars from hemicellulose is a
major product of the hemicellulose hydrolysis. Utilization of this carbon source would
significantly increase the ethanol yield from...
The economically viable production of value added fuels and chemicals from lignocellulosic feedstocks hinges on our ability to quickly and efficiently transform structural carbon molecules to end products. The sugars in lignocellulosic biomass are held primarily within cellulose and hemicellulose. Cellulose is composed primarily of glucose monomers which are quickly...
The production of fuel ethanol from lignocellulosic biomass has the potential to replace a significant portion of non-renewable transport fuels. Woody feedstocks are composed of cellulose, hemicellulose, and lignin. Glucose, the monomer of cellulose, is readily utilized by wild-type S. cerevisiae, but xylose, which comprises 60% of the sugar in...
Studies investigating the effects of feeding diets
containing the yeast, Saccharomyces cerevisiae var.
boulardii (SCB), and a yeast culture (YC) containing S.
cerevisiae were conducted in market turkeys and Medium White
turkey breeder hens.
Increased utilization of dietary gross energy, N, Ca,
P, B, K, Mg, and Mn were observed...
In budding yeast, many of the genes that encode enzymes required for DNA precursor synthesis (MCB genes) are expressed under cell cycle control in late G1/S. The relationship between MCB gene expression, dNTP synthesis and DNA synthesis was investigated by using α factor-synchronized Saccharomyces cerevisiae. The levels of all four...
In an effort to understand the basis for sulfite detoxification in S. cerevisiae,
the functions of two genes were analyzed. SSU1, which encodes a plasma membrane
protein, was found to be required for efficient sulfite efflux. FZFl-4, a dominant
allele of a transcriptional activator of SSUl, was also found to...
The studies described in this thesis were motivated by ongoing efforts to develop lignocellulosic biomass as an efficient and practical source of renewable energy. Enormous problems complicate these efforts to reduce reliance on greenhouse gas-generating fossil fuels. Simply obtaining the fermentable sugars available in the cellulose and hemicellulose components of...
Malolactic fermentation (MLF) is important in the production of wines as it reduces acidity through the conversion of malic acid to lactic acid. However, successful MLF can be difficult to achieve due to yeast antagonism of the bacterium responsible for
the secondary fermentation, Oenococcus oeni. In particular, yeast produced sulfur...
Fermentation of the grape must into wine is one of the most important steps in winemaking. Selected yeast strains of Saccharomyces cerevisiae have been used for many years to ensure complete and even fermentations. The formation of volatile compounds also occurs during fermentation and will influence the sensory perception of...