magistrsko delo
Aleš Ogrinec (Avtor), Tomaž Accetto (Recenzent), Neža Čadež (Mentor), Neža Čadež (Član komisije za zagovor), Mojca Narat (Član komisije za zagovor), Tomaž Accetto (Član komisije za zagovor)

Povzetek

Cilj magistrske naloge je bil proučiti vpliv zaporedne uporabe kvasne biomase na izražanje genov vključenih v metabolno pot valina in to primerjati s koncentracijo diacetila v pivu ter drugih pomembnih aromatičnih komponent v pivu. Iz 31 zaporednih fermentacij piva, ki smo jih izvedli v mikro-fermentacijskem sistemu, ki je posnemal industrijske pogoje, smo odvzeli vzorce kvasne biomase za izolacijo RNA in jo prepisali v cDNA. S kvantitativnim PCR smo ugotovili spremembe v izražanju genov BDH1, BDH2, ILV2 in ILV6, ki kodirajo encime, ki so pomembni v metabolni poti valina in posledično vplivajo na produkcijo diacetila, katerega koncentracija se spreminja med zaporednimi uporabami kvasovk. V primerjavi s prvo fermentacijo, smo opazili naraščajoči trend izražanja vseh preiskovanih genov pri nadaljnjih zaporednih fermentacijah, do največjih sprememb je prišlo v izražanju gena BDH1, nekoliko manjših sprememb izražanja genov ILV2 in ILV6. Najmanjše spremembe v izražanju smo opazili pri genu BDH2. Koncentracije, diacetila in ostalih pomembnih aromatičnih spojin, acetaldehida, dimetil sulfida, propanola, izobutanola, etilacetata in izoamilacetata ki so bile določene s plinsko kromatografijo so pokazale, da pri zaporednih fermentacijah pride do sprememb tudi pri produkciji aromatičnih komponent piva. Kot posledica prekomerne zaporedne uporabe je diacetil presegel prag senzorične zaznave. Korelacije med preiskovanimi geni in koncentracijo diacetila v pivu nismo mogli potrditi.

Ključne besede

diacetil;zaporedne fermentacije;pivo;Saccharomyces pastorianus;ekspresija genov;

Podatki

Jezik: Slovenski jezik
Leto izida:
Tipologija: 2.09 - Magistrsko delo
Organizacija: UL BF - Biotehniška fakulteta
Založnik: [A. Ogrinec]
UDK: 602.3:582.282.23:579.25(043.2)
COBISS: 9100665 Povezava se bo odprla v novem oknu
Št. ogledov: 861
Št. prenosov: 341
Ocena: 0 (0 glasov)
Metapodatki: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Ostali podatki

Sekundarni jezik: Angleški jezik
Sekundarni naslov: Analysis of genes expression involved in diacetyl pathway between successive beer fermentation
Sekundarni povzetek: The aim of the master's thesis was to study the influence of the serial repitching of yeast biomass for the expression of genes involved in the metabolic pathway of valine and compare this with the concentration of diacetyl in beer and other important aromatic components in beer. From 31 successive beer fermentations carried out in a micro-fermentation system that mimicked industrial conditions, yeast biomass was taken for RNA isolation and was transcribed to cDNA. With quantitative PCR, changes in the expression of the BDH1, BDH2, ILV2 and ILV6 genes were analysed. These genes encode enzymes that are important in the valine metabolic pathway and consequently influence the production of diacetyl which concentration varies between successive use of yeast bimass. Compared to the first fermentation, we observed an increasing trend in the expression of all investigated genes in subsequent successive fermentations. The greatest changes occurred in the expression of the BDH1 gene, slightly smaller for genes ILV2 and ILV6. The smallest changes in expression were observed in the BDH2 gene. The concentration of diacetyl and other important aromatic compounds, acetaldehyde, dimethyl sulphide, propanol, isobutanol, ethyl acetate and isoamyl acetate determined by gas chromatography showed that changes in the production of aromatic beer components occur in successive fermentations. As a result of excessive successive use, diacetyl exceeded the sensory threshold. Correlation between the investigated genes and the concentration of diacetyl in beer could not be confirmed.
Sekundarne ključne besede: diacetyl;successive fermentation;genes expression;
Vrsta dela (COBISS): Magistrsko delo/naloga
Študijski program: 0
Komentar na gradivo: Univ. v Ljubljani, Biotehniška fak., Študij biotehnologije
Strani: X, 55 f.
ID: 10983223