magistrsko delo
Petra Šenica (Avtor), Uroš Petrovič (Recenzent), Hrvoje Petković (Mentor), Miha Tome (Komentor)

Povzetek

Kvasovka Saccharomyces cerevisiae je eden od modelnih organizmov za evkariontske celice, ki se pogosto uporablja v industriji. Kvasovke se že tisočletja uporablja v proizvodnji piva, predvsem zaradi dobre zmožnosti izkoriščanja ogljikovih hidratov kot vira energije. V pivovarski industriji uporaba rekombinantnih tehnik za manipulacijo mikroorganizmov ni dovoljena, zato je za izboljšave sevov potrebno poseči po drugačnih pristopih. Eden od primerov je usmerjena evolucija z mutagenezo, kjer med povzročenimi mutacijami s selekcijskim pritiskom izberemo tiste, ki so odgovorne za želeni fenotip. Eden izmed ciljev magistrskega dela je bila tako postavitev metodologije usmerjene evolucije. Z UV in EMS mutagenezo ter gojenjem na gojišču YNB z maltozo kot edinim virom ogljika ob prisotnosti 2-deoksi glukoze (2DG) v vlogi selekcijskega pritiska smo pridobili proti 2DG odporne mutante industrijskega seva S. cerevisiae. Te mutante smo testirali v fermentacijah, sprva v manjšem volumnu (2 mL), potem pa smo 12 po fenotipu primernih izolatov podrobno testirali še v večjem volumnu (50 mL). S pomočjo HPLC smo merili vsebnost glukoze, maltoze, glicerola in etanola v času bioprocesa, z namenom ugotovitve, koliko in v kakšnem zaporedju je posamezen sev porabljal maltozo in glukozo. Ugotovili smo, da smo pri določenih sevih odpravili katabolno represijo z glukozo, saj so sevi spremenili zaporedje porabe sladkorjev glede na kontrolni sev S. cerevisiae.

Ključne besede

kvasovke;Saccharomyces cerevisiae;proizvodnja piva;fermentacija piva;poraba sladkorjev;glukoza;maltoza;usmerjena evolucija;mutageneza;selekcijski pritisk;

Podatki

Jezik: Slovenski jezik
Leto izida:
Tipologija: 2.09 - Magistrsko delo
Organizacija: UL BF - Biotehniška fakulteta
Založnik: [P. Šenica]
UDK: 663.45:602.3:582.282.23:575.224.4
COBISS: 70423811 Povezava se bo odprla v novem oknu
Št. ogledov: 492
Št. prenosov: 78
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: Improving physiological traits of brewing yeasts with directed evolution
Sekundarni povzetek: The yeast Saccharomyces cerevisiae is one of model organisms for eukaryotic cells and it often used in industry. It is one of the most widely used organisms and, due to its efficient utilization of carbohydrates in the fermentation process, it has been used in beer production for centuries. The use of recombinant techniques for genetic manipulation of microorganisms is not welcomed in the food industry. Therefore, other strain improvement techniques have to be used. One of them is application of directed evolution with mutagenesis; via selection pressure, we can isolate mutants with improved phenotype which can be beneficial for example in the beer production process. The main goal of this work was to establish and evaluate the methodology of directed evolution in yeast to generate mutants with desired traits. Using UV and EMS mutagenesis and cultivation on YNB medium containing maltose as the sole carbon source and 2-deoxyglucose (2DG) as the selective pressure, we obtained several 2DG-resistant mutants of the industrial strain S. cerevisiae. To evaluate the phenotype of the isolated mutants, we initially carried out fermentation in smaller volume (2 ml). We then selected 12 mutants and evaluated glucose and maltose utilization ability, which was tested in fermentations at a 50 ml scale. The content of glucose, maltose, glycerol and ethanol was measured by HPLC. The amount of glucose and maltose consumed during fermentation was compared to the parent strain. We were able to successfully abolish catabolic repression with glucose in selected mutants, considering that altered succession of sugar utilization was observed compared to the parent strain.
Sekundarne ključne besede: yeasts;Saccharomyces cerevisiae;beer production;beer fermentation;carbohydrates;glucose;maltose;directed evolution;mutagenesis;selection pressure;
Vrsta dela (COBISS): Magistrsko delo/naloga
Študijski program: 0
Komentar na gradivo: Univ. v Ljubljani, Biotehniška fak., Študij mikrobiologije
Strani: XIII, 63 f., [23] f. pril.
ID: 13153752