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dc.contributor.advisorKock, J. L. F.
dc.contributor.advisorSwart, C. W.
dc.contributor.advisorVan Wyk, P. W. J.
dc.contributor.advisorPohl, C. H.
dc.contributor.advisorLodolo, E. J.
dc.contributor.authorDithebe, Khumisho
dc.date.accessioned2015-09-04T07:57:18Z
dc.date.available2015-09-04T07:57:18Z
dc.date.copyright2013-11
dc.date.issued2013-11
dc.date.submitted2013-11
dc.identifier.urihttp://hdl.handle.net/11660/1162
dc.description.abstractEnglish: It has previously been implicated in literature that intracellular gas bubbles cannot form in yeast cells even under high gas supersaturation conditions. Furthermore, not even protein-coated gas vesicles found in Cyanobacteria are expected in yeasts. The lack of intracellular gas bubbles has been attributed to the increased structuring of water and lack of water with nucleation properties. This, however, is considered a missing link since yeasts, the workhorses of the baking and brewing industry, are known to produce and vigorously release carbon dioxide (CO2) gas during fermentation. Here we resolve the missing link between CO2 production by glycolysis and the eventual release of CO2 from the cells, and show that yeasts are capable of producing intracellular gas bubbles which were found to occupy a significant part of the cell. These gas bubbles do not contain a membrane that surrounds them. Furthermore, addition of zinc to the growth medium resulted in the “galvanization” of the bubbles suggesting that the gas bubbles may possibly contain CO2. These findings should pave way for future research on CO2 behaviour under pressurized conditions that may have an impact on fermentation biotechnology. Furthermore we show that these intracellular gas bubbles deform cell organelles such as the nucleus. The skin surrounding the gas bubbles is able to withstand tension as they do not disintegrate when they come in contact with organelle membranes. Further research should now be performed on the mechanical effects of the gas bubbles on metabolic and coding functions of yeasts as gas bubbles deform and contort cell organelles. From these findings careful consideration is required during optimization of fermentation parameters to prevent CO2 toxicity effects on fermentation performance and flavor formation in practical brewing.en_ZA
dc.description.abstractAfrikaans: Volgens literatuur, kan intrasellulêre gasborrels nie in gisselle gevorm word nie, selfs nie onder hoë gassupersaturasie nie. Verder word selfs nie eens proteïenomhulde gasvesikels wat in Cyanobakterieë voorkom verwag in gisselle nie. Die afwesigheid van intrasellulêre gasborrels was toegeskryf aan die verhoogde strukturering van water en tekort aan water met kernvormingseienskappe. Die afwesigheid van gasborrels word as „n raaisel beskou aangesien giste, die werkesels van die bak en bierbrou industrieë, bekend is vir die vrystelling van groot hoeveelhede koolstofdioksied (CO2) tydens fermentasie. In hierdie stuk verklaar ons die raaisel aangaande die produksie van CO2 deur glikolise en die uiteindelike vrystelling van CO2 vanuit die selle en wys ons dat giste oor die vermoë beskik om intrasellulêre gasborrels to vorm wat „n groot deel van die selvolume uitmaak. Hierdie gasborrels het geen membraanomhulsel nie. Wanneer sink by die groeimedium gevoeg word vind daar “galvanisering” van die borrels plaas wat impliseer dat hierdie gasborrels CO2 bevat. Hierdie resultate behoort die weg te baan vir toekomstige navorsing rakende die optrede van CO2 onder druk en dit mag moontlik „n impak hê op biotegnologiese fermentasies. Verder wys ons ook dat hierdie borrels die selorganelle, soos onder andere die kern, vervorm. Die “vel” rondom die gasborrels kan drukking weerstaan en dus disintergreer die borrels nie wanneer dit in kontak kom met die organelmembraan nie. Verdere navorsing moet nou volg om die meganiese effek van die gasborrels op die metaboliese en koderingsfunksies van die gisselle te bepaal aangesien die borrels die organelle vervorm. Na aanleiding van hierdie resultate moet die vorming van gasborrels in ag geneem word tydens die optimisering van fermentasie parameters om CO2 toksisiteit te voorkom.af
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectCytoplasmen_ZA
dc.subjectYeasten_ZA
dc.subjectCell organelles -- Formationen_US
dc.subjectDissertation (M.Sc. (Microbial, Biochemical and Biotechnology))--University of the Free State, 2013en_ZA
dc.subjectBrewing yeasten_ZA
dc.subjectCarbon dioxideen_ZA
dc.subjectCompressionen_ZA
dc.subjectDeformationen_ZA
dc.subjectFermentationen_ZA
dc.subjectIntracellular gas bubblesen_ZA
dc.subjectNanoSAMen_ZA
dc.subjectOrganellesen_ZA
dc.titleGas bubble formation in the cytoplasm yeasten_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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