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You searched for +publisher:"University of Adelaide" +contributor:("Sundstrom, Joanna F"). Showing records 1 – 2 of 2 total matches.

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University of Adelaide

1. Tek, Ee Lin. Phenotypic investigation of biofilm formation and transcriptional analysis of invasive growth of commercial wine Saccharomyces cerevisiae.

Degree: 2017, University of Adelaide

This study investigated the morphological properties, environmental effects on and gene expression of biofilms, more specifically referred to as mats, formed by laboratory and commercial wine strains of Saccharomyces cerevisiae. Two morphological assays were conducted: mat formation and plastic adhesion. Mat features varied between strains and included various architectures, cellular morphologies, and incidence of invasive growth. One commercial strain, L2056, formed mats where a sector produced a distinctive mat morphology, which was retained when subcultured. In considering the role of biofilms in winery conditions, mat formation assays were also performed with grape pulp and adhesion to the soft plastic of common winery hoses. All strains grew invasively on all agar media and appeared to conduct fermentation on the grape-pulp mat assay. Some strains also had the ability to adhere to winery hose plastic. When only limited nitrogen was available, both laboratory and commercial wine strains formed mats with a subpopulation of cells that switched to filamentous and invasive growth. Such invasive growth was influenced by nitrogen concentration, the presence of a neighbouring mat, and by the addition of yeast metabolites. Ethanol and hydrogen sulfide were found to enhance invasive growth of cells within mats exposed to low levels of nitrogen whereas tryptophol and 2-phenylethanol suppressed this enhancement. Sulfite was found to delay overall mat growth. In an effort to understand the cellular decision to switch morphology, changes in the transcriptome of invasively growing cells were studied. In this analysis, 272 genes were identified to be upregulated and 84 genes were downregulated in invasively growing cells. Of the ten largest differentially expressed genes, four were genes encoding hexose transporters (HXT3, HXT4, HXT6 and HXT7) which had an increase in transcript abundance up to 13-fold. One hypothetical gene (AWRI796_5153) with a 6-fold increase in transcript abundance, has translation sequence homologous to an amidase domain. Following differential expression and Gene Ontology analysis, five GO categories represented the 37 significantly enriched GO terms in the upregulated gene set of invasively growing cells, these being glucose import, carbohydrate metabolic process, fungal-type cell wall organisation, medium-chain fatty acid biosynthetic process and cellular water homeostasis. Since cellular water homeostasis has not previously been associated with invasive growth, and four out of five genes in this group were found to be significantly upregulated in the invasively growing cells, further analysis of deletion mutants of each of these confirmed that FPS1, encoding the glycerol export protein, is required for invasive growth of yeast mats in low nitrogen conditions. In summary, this work reports the phenotypic properties of commercial wine yeast biofilms in environments of both rich nutrient and low nitrogen, either in typical laboratory type agar media or in conditions simulating that of a grape or wine… Advisors/Committee Members: Jiranek, Vladimir (advisor), Sundstrom, Joanna F (advisor), Gardner, Jennifer Margaret (advisor), School of Agriculture, Food and Wine (school).

Subjects/Keywords: Saccharomyces cerevisiae; wine yeast; biofilm; mat; invasive growth; Research by Publication

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Tek, E. L. (2017). Phenotypic investigation of biofilm formation and transcriptional analysis of invasive growth of commercial wine Saccharomyces cerevisiae. (Thesis). University of Adelaide. Retrieved from http://hdl.handle.net/2440/113361

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Tek, Ee Lin. “Phenotypic investigation of biofilm formation and transcriptional analysis of invasive growth of commercial wine Saccharomyces cerevisiae.” 2017. Thesis, University of Adelaide. Accessed August 25, 2019. http://hdl.handle.net/2440/113361.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Tek, Ee Lin. “Phenotypic investigation of biofilm formation and transcriptional analysis of invasive growth of commercial wine Saccharomyces cerevisiae.” 2017. Web. 25 Aug 2019.

Vancouver:

Tek EL. Phenotypic investigation of biofilm formation and transcriptional analysis of invasive growth of commercial wine Saccharomyces cerevisiae. [Internet] [Thesis]. University of Adelaide; 2017. [cited 2019 Aug 25]. Available from: http://hdl.handle.net/2440/113361.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Tek EL. Phenotypic investigation of biofilm formation and transcriptional analysis of invasive growth of commercial wine Saccharomyces cerevisiae. [Thesis]. University of Adelaide; 2017. Available from: http://hdl.handle.net/2440/113361

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Adelaide

2. Jiang, Jiao. Use of directed evolution to generate multiple-stress tolerant Oenococcus oeni for enhanced malolactic fermentation.

Degree: 2017, University of Adelaide

This study aimed to optimise Oenococcus oeni for more efficient malolactic fermentation in wine with multiple stressors. First, a previously evolved ethanol tolerant strain, A90, was characterised for resistance to combined pH and ethanol stress in both MRSAJ and Red Fermented Chemically Defined Grape Juice Medium (RFCDGJM). A90 showed a similar viability in RFCDGJM compared to its parent, SB3, indicating the need for further improvement. With the success of the previous proof-of-concept directed evolution (DE) in O. oeni, a new DE was carried out to determine 1) if DE can be applied to further improve A90 in a wine-like environment using combinations of stressors to generate more superior strains with better general stress resistance; 2) how much further can A90 be developed, and how stable the new phenotype would be; 3) possible new patterns of stress response through study of the genetic basis for the superior phenotype. A continuous culture of A90 was established in a bioreactor and grown in a wine-like environment for approximately 350 generations with increasing ethanol and sulfur dioxide (SO₂), and decreasing pH over time. Samples of the population in the bioreactor were collected at three significant times during the DE to screen for improved isolates based on L-malic acid consumption and growth. Three strains, namely 1-161, 2-49 and 3-83, outperformed from a total of 378 isolates. With a view to applying these strains to the industry, in-depth physiological characterisations were undertaken. Aspects examined included tolerance to various oenologically related stressors such as ethanol, pH, SO₂ and medium chain fatty acids, as well as phenotype stability and fermentation ability under more realistic winemaking conditions, i.e. un-filtered wine and winery scale fermentation. Overall, 2-49 and 3-83 constantly displayed better growth and malolactic activity than the parent strain A90 in either lab-scale or winery-scale trials. Finally, whole genome sequencing of strains SB3, A90, 2-49 and 3-83 and genetic characterisation were utilised to investigate changes during DE in O. oeni. A total of 19 single nucleotide polymorphisms (SNPs) were found in 2-49 and 3-83 strains compared to A90. The SNPs identified may affect cell envelope and fatty acids biosynthesis, DNA translation and homeostasis of internal pH, leading to the improved performance of DE strains. Sequences were also compared to the available sequence for commercial strain VP41. Several mutations were identified in stress response genes, indicating VP41 and SB3-related strains might have different responses to stressors. SNPs in the predicted mleA promoter sequence may suggest a new mechanism of MLF activation. Additionally, Nucleotide BLAST was used to analyse the presence of genes with oenological traits in SB3-related strains. Genes associated with the release of desirable aromas were found, whilst genes involved in the formation of biogenic amines were absent. This study expands the knowledge regarding optimisation of O. oeni, and may be helpful for… Advisors/Committee Members: Jiranek, Vladimir (advisor), Grbin, Paul Ramon (advisor), Sumby, Krista M (advisor), Sundstrom, Joanna F (advisor), School of Agriculture, Food and Wine (school).

Subjects/Keywords: directed evolution; Oenococcus oeni; multiple-stress; malolactic fermentation; whole genome sequencing; Research by Publication

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Jiang, J. (2017). Use of directed evolution to generate multiple-stress tolerant Oenococcus oeni for enhanced malolactic fermentation. (Thesis). University of Adelaide. Retrieved from http://hdl.handle.net/2440/114505

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Jiang, Jiao. “Use of directed evolution to generate multiple-stress tolerant Oenococcus oeni for enhanced malolactic fermentation.” 2017. Thesis, University of Adelaide. Accessed August 25, 2019. http://hdl.handle.net/2440/114505.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Jiang, Jiao. “Use of directed evolution to generate multiple-stress tolerant Oenococcus oeni for enhanced malolactic fermentation.” 2017. Web. 25 Aug 2019.

Vancouver:

Jiang J. Use of directed evolution to generate multiple-stress tolerant Oenococcus oeni for enhanced malolactic fermentation. [Internet] [Thesis]. University of Adelaide; 2017. [cited 2019 Aug 25]. Available from: http://hdl.handle.net/2440/114505.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Jiang J. Use of directed evolution to generate multiple-stress tolerant Oenococcus oeni for enhanced malolactic fermentation. [Thesis]. University of Adelaide; 2017. Available from: http://hdl.handle.net/2440/114505

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.