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The physiological impact of exogenous phenylalanine on an oenological isolate of Kluyveromyces marxianus
Thesis (MScAgric)--Stellenbosch University, 2022.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2022
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| _version_ | 1867613966853734400 |
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| access_status_str | Open Access |
| author | Degenaar, Nadia |
| author2 | Divol, Benoit |
| author_browse | Degenaar, Nadia Divol, Benoit |
| author_facet | Divol, Benoit Degenaar, Nadia |
| author_sort | Degenaar, Nadia |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/125139 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:33.029Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/125139 The physiological impact of exogenous phenylalanine on an oenological isolate of Kluyveromyces marxianus Degenaar, Nadia Divol, Benoit Stellenbosch University. Faculty of Agrisciences. Dept. of Viticulture and Oenology. Kluyveromyces marxianus Phenylalanine -- Metabolism Ethanol Lipids Grapes -- South Africa Yeast -- Effect of stress on UCTD Thesis (MScAgric)--Stellenbosch University, 2022. ENGLISH ABSTRACT: A strain of Kluyveromyces marxianus, IWBT Y885, isolated from South African grape must within our research environment, shows promising attributes including increased production of the volatile alcohol 2- phenylethanol (2-PE) and its acetate ester derivative, 2-phenylethyl acetate (2-PEA). These compounds confer sweet, floral aromas and are therefore valuable to industries ranging from cosmetics to food and (alcoholic) beverages and can be produced from sugar and the aromatic amino acid (AAA) L-phenylalanine (Phe)’s catabolism via the Shikimate and Ehrlich pathways, respectively. The recently reported increased flux distribution of Phe toward the Ehrlich pathway in K. marxianus Y885 makes this yeast a promising candidate for biotechnological applications of 2-PE and 2-PEA production. Within this study, fungal Phe metabolism was extensively reviewed to provide adequate background of the intricacies at play in Phe-derived metabolite production by various yeasts. The research component of this thesis predominantly focusses on the catabolism of Phe via the Ehrlich pathway to produce 2-PE and 2-PEA in response to exogenous Phe supplementation, as well as assessing the consequent physiological impact of the amino acid on K. marxianus Y885 in terms of cell viability, fermentation performance, and further downstream impacts on lipid and amino acid metabolism. In terms of viability and fermentation performance, K. marxianus Y885 was found to experience comparatively greater sensitivity to Phe than Saccharomyces cerevisiae and other strains of K. marxianus. Notably, we demonstrated that K. marxianus strains fermented sugars more effectively in the absence of Phe. Furthermore, lipid supplementation did not mitigate any deleterious effects of Phe, however, they generally aided in viability maintenance and fermentation performance in the absence of Phe. Valuable foundational insight was gained into differing lipid utilisation between the two yeast species as well. Where aroma production is concerned, supplementing Phe augmented the production of 2-PE, with maximum titres of 3961.7±809.2 µM and 8386.9±1662.4 µM achieved for K. marxianus Y885 and S. cerevisiae EC1118, respectively. K. marxianus Y885 exhibited a higher production capability of 2-PEA, which suggests that this enhanced conversion be, at least in part, a compensatory detoxification mechanism for K. marxianus Y885, when considering this yeast’s sensitivity to Phe. Additionally, based on branched- chain amino acid (BCAA)-derived volatile outputs, links between BCAA and AAA catabolism via the Ehrlich pathway as well as potential regulatory mechanisms at play within this pathway were established. This study ultimately contributes to foundational knowledge of the unique metabolic regulation of Phe catabolism in K. marxianus Y885. The data generated indicate that regulatory mechanisms differ inter- and intra-specifically, thereby providing potentially relevant information for a variety of biotechnological applications, including winemaking. AFRIKAANSE OPSOMMING: ‘n Ras van Kluyveromyces marxianus, genoem IWBT Y885, wat geïsoleer is uit Suid-Afrikaanse druiwesap binne ons navorsingsomgewing, toon belowende eienskappe. Díe sluit in die verhoogde produksie van die vlugtige alkohol 2-fenieletanol (2-PE) en sy asetaat ester derivaat, 2-fenieletiel asetaat (2-PEA). Hierdie verbindings verleen soet, florele aromas en is dus waardevol vir verskeidende nywerhede- van skoonheidsmiddels tot voedsel en (alkoholiese) drinkgoed- en kan vervaardig word van die katabolisme van beide suikers, en die aromatiese aminosuur (AAA) L-fenylalanien (Phe) via die Shikimate en Ehrlich- paaie, onderskeidelik. Die onlangs gerapporteerde verhoogde vloedverspreiding van Phe na die Ehrlich- weg in K. marxianus Y885 maak hierdie gissoort 'n belowende kandidaat vir biotegnologiese toepassings van 2-PE- en 2-PEA-produksie. Ingevolge hierdie studie is Phe-metabolisme in swamme omvattend hersien om voldoende agtergrond te verskaf van die kompleksiteit wat voorkom in Phe-afgeleide metabolietproduksie deur verskeie giste. Die navorsingskomponent van hierdie tesis fokus hoofsaaklik op die katabolisme van Phe via die Ehrlich-weg om 2-PE en 2-PEA te produseer in reaksie tot eksogene Phe-aanvulling, asook die beoordeling van die gevolglike fisiologiese impak van die aminosuur op K. marxianus Y885 in terme van sellewensvatbaarheid, fermentasiegedrag en effekte verder in die proses af op lipied- en aminosuurmetabolisme. Wat lewensvatbaarheid en fermentasiegedrag betref, het ons gevind dat K. marxianus Y885 ‘n betreklike hoër sensitiwiteit teenoor Phe toon as Saccharomyces cerevisiae en ander rasse van K. marxianus. Ons het veral bewys dat K. marxianus oor die algemeen suikers meer effektief fermenteer in die afwesigheid van Phe. Verder het lipiedaanvullings geen newe effekte van Phe verbeter nie, maar oor die algemeen die werksaamheid van fermentasie ondersteun as gevolg van die instandhouding van lewensvatbaarheid in die afwesigheid van Phe. Waardevolle fundamentele insig is ook verkry oor verskille in lipiedbenutting tussen die twee gisspesies. Wat aromaproduksie betref, het die aanvulling van Phe die produksie van 2-PE verhoog, met maksimum konsentrasies van 3961.7±809.2 µM en 8386.9±1662.4 µM wat behaal is vir K. marxianus Y885 en S. cerevisiae EC1118, onderskeidelik. K. marxianus Y885 het 'n hoër produksievermoë van 2- PEA getoon, wat daarop dui dat hierdie verbeterde omskakeling, ten minste gedeeltelik, moontlik 'n kompenserende ontgiftingsmeganisme vir K. marxianus Y885 is as hierdie gis se sensitiwiteit aan Phe oorweeg word. Boonop, gebaseer op vertakte-ketting aminosuur (BCAA)-afgeleide aromaproduksie, is skakels tussen BCAA en AAA katabolisme via die Ehrlich-pad, sowel as potensiële regulatoriese meganismes wat binne hierdie pad plaasvind, vasgestel. Hierdie studie dra uiteindelik by tot grondliggende kennis van die unieke metaboliese regulering van Phe katabolisme in K. marxianus Y885. Die data wat gegenereer is, dui daarop aan dat regulatoriese meganismes inter- en intraspesifiek verskil, en voorsien potensieële relevante inligting vir 'n verskeidenheid van biotegnologiese toepassings, insluitend van wynmaak. Masters 2022-03-10T21:05:04Z 2022-04-29T12:55:41Z 2023-05-03T03:00:11Z 2022-04 Thesis http://hdl.handle.net/10019.1/125139 en_ZA Stellenbosch University 67 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Kluyveromyces marxianus Phenylalanine -- Metabolism Ethanol Lipids Grapes -- South Africa Yeast -- Effect of stress on UCTD Degenaar, Nadia The physiological impact of exogenous phenylalanine on an oenological isolate of Kluyveromyces marxianus |
| title | The physiological impact of exogenous phenylalanine on an oenological isolate of Kluyveromyces marxianus |
| title_full | The physiological impact of exogenous phenylalanine on an oenological isolate of Kluyveromyces marxianus |
| title_fullStr | The physiological impact of exogenous phenylalanine on an oenological isolate of Kluyveromyces marxianus |
| title_full_unstemmed | The physiological impact of exogenous phenylalanine on an oenological isolate of Kluyveromyces marxianus |
| title_short | The physiological impact of exogenous phenylalanine on an oenological isolate of Kluyveromyces marxianus |
| title_sort | physiological impact of exogenous phenylalanine on an oenological isolate of kluyveromyces marxianus |
| topic | Kluyveromyces marxianus Phenylalanine -- Metabolism Ethanol Lipids Grapes -- South Africa Yeast -- Effect of stress on UCTD |
| url | http://hdl.handle.net/10019.1/125139 |
| work_keys_str_mv | AT degenaarnadia thephysiologicalimpactofexogenousphenylalanineonanoenologicalisolateofkluyveromycesmarxianus AT degenaarnadia physiologicalimpactofexogenousphenylalanineonanoenologicalisolateofkluyveromycesmarxianus |