Plasmid analysis, comparative genomics and transcriptomics of beer-spoilage lactic acid bacteria emphasizing the role of dissolved carbon dioxide and traditional beer-spoilage markers

Bergsveinson, Jordyn 1990-

Plasmid analysis, comparative genomics and transcriptomics of beer-spoilage lactic acid bacteria emphasizing the role of dissolved carbon dioxide and traditional beer-spoilage markers

dc.contributor.committeeMember	Ziola, Barry
dc.contributor.committeeMember	Mckay, Gordon
dc.contributor.committeeMember	Deneer, Harry
dc.contributor.committeeMember	Korber, Darren
dc.contributor.committeeMember	White, Aaron
dc.creator	Bergsveinson, Jordyn 1990-
dc.date.accessioned	2020-02-11T20:52:35Z
dc.date.available	2020-02-11T20:52:35Z
dc.date.created	2015-11
dc.date.submitted	November 2015
dc.date.updated	2020-02-11T20:52:35Z
dc.description.abstract	Specific isolates of lactic acid bacteria (LAB) are capable of growing in and spoiling beer, and are the cause of product and process contamination, and financial loss for brewers the world over. To date, our understanding of how these contaminants are able to grow in beer is limited to analysis of hop-tolerance mechanisms, with a limited number of putative hop-tolerance genes having been described. In order to demonstrate that these hop-tolerance genes are incomplete descriptors of overall beer-spoilage ability, the transcriptional activity of these genes in two different beer-spoilage related (BSR) LAB isolates, and the prevalence and sequence conservation of hop-tolerance gene horC in BSR LAB with varying beer-spoilage ability is examined. This analysis is followed by work demonstrating that the total plasmid profile of a beer-spoilage LAB, and not just plasmids harboring hop-tolerance genes, contributes to the isolate’s overall beer-spoilage phenotype and highlights redundancy in potential beer-spoilage mechanisms. The next chapter provides evidence that the presence of dissolved CO2 (dCO2) in beer selects for the ability of LAB to spoil packaged beer, and that tolerance to this stress is not correlated with hop-tolerance, indicating that dCO2 stress is an important part of the total beer environment. This is followed by the presentation and analysis of the genome of the rapid beer-spoiling isolate Lactobacillus brevis BSO 464 and subsequent RNA sequencing for this isolate when grown in degassed and gassed beer so as to elucidate which genes are active when grown in beer, and when grown specifically in the presence of dCO2. Global transcriptome sequencing of this L. brevis isolate and Pediococcus claussenii ATCC BAA-344T when each were grown in growth-limiting concentrations of hops was also performed in order to clarify the hop-specific transcriptional response from that of the response when these isolates grow in the total beer environment. Lastly, comparison is made between available genomes of BSR LAB to reveal that the specific brewery environment a BSR LAB is recovered from, influences genetic variability and that comparison within a given LAB species reveals genetic differences that can be exploited as beer-spoilage genetic markers. This comparative analysis reveals that the total plasmid-coding capacity strongly influences individual BSR LAB beer-spoilage phenotype and the environment they are able to grow in. Overall, beer-spoilage ability is shown to be adaptive and acquired incrementally and not solely as a result of the presence of hop-tolerance genes.
dc.format.mimetype	application/pdf
dc.identifier.uri	http://hdl.handle.net/10388/12613
dc.subject	Beer-spoilage
dc.subject	Brewing
dc.subject	Genomics
dc.subject	Hop-tolerance
dc.subject	Lactic acid bacteria
dc.subject	Plasmid analysis
dc.subject	RNA sequencing
dc.subject	Transcriptomics
dc.title	Plasmid analysis, comparative genomics and transcriptomics of beer-spoilage lactic acid bacteria emphasizing the role of dissolved carbon dioxide and traditional beer-spoilage markers
dc.type	Thesis
dc.type.material	text
thesis.degree.department	Medicine
thesis.degree.discipline	Health Sciences
thesis.degree.grantor	University of Saskatchewan
thesis.degree.level	Doctoral
thesis.degree.name	Doctor of Philosophy (Ph.D.)