Search

Opravili smo dve hitri molekularni tehniki za identifikacijo enoloških kvasovk, ki so bile izolirane iz vinogradov z ekološko in intergrirano pridelavo grozdja. Najprej smo določili 15 Saccharomyces kvasovk s pomočjo analize multipleks PCR med zbranimi 131 izolati, nato smo s pomočjo ribotipizacije ITS določili približno 98 kvasovk do nivoja vrste, ki so bile potrjene tudi s sekvenciranjem regije ITS. Določili smo 16 vrst vinskih kvasovk: Hanseniaspora uvarum, H. valbyensis, H. opuntiae / H. uvarum, Lachancea thermotolerans, Candida tropicalis, Candida sp. / Starmerella sp., Metschnikowia pulcherrima, Pichia kudriavzevii, P. terricola, P. kluyveri, Wickerhamomyces anomalus, Kodamaea ohmeri, S. bacillaris, Saccharomyces cerevisiae, Saturnispora diversa in Torulaspora delbrueckii. Ugotovili smo, da so najdene kvasovke običajne naseljevalke grozdne mikroflore ter da je način pridelave grozdja vplival na pojavljanje določenih vrst v obravnavanih vinogradih. Nadalje smo testirali kvasovke na tvorbo sideroforov, tvorbo protiglivnih hlapnih organskih spojin (HOS), hidrolitično aktivnost in toleranco kvasovk na fungicide, kot so baker, iprodion, fluazinam ter kombinacijo ciprodinil / fludioksonil. Za kvalitativno detekcijo hidrolitične aktivnosti smo uporabili presejalne teste na osnovi trdnega gojišča z dodanim hitinom ali β-D-glukozidi kot substratom in ugotovili, da je veliko testiranih kvasovk sposobnih proizvajati litične encime, ki bi lahko bili odgovorni za razgradnjo celičnih sten fitopatogenih gliv in potencialno sposobni proizvajati HOS s hidrolizo grozdnih glikozidov zaradi prisotnosti β-glukozidaz. Prav tako smo opazili, da so te encimske aktivnosti običajno odvisne od seva. Na splošno so kvasovke tudi tolerantne na testirane fungicide. Ugotovili smo tudi, da je odpornost biofungicidnih kvasovk na fungicide koristna lastnost za razvoj biofungicidov v prihodnosti pri aplikacijah v strategijah z zmanjšanim vnosom pesticidov. We performed two rapid molecular techniques for the identification of enological yeasts that were collected from vineyards with organic and integreated pest management. First we distinguised 15 Saccharomyces yeasts with multiplex PCR analysis from collected 131 isolates, further on we identified approx. 98 isolates to species level based on ITS ribotyping that were confirmed also with ITS sequencing. Overall we distinguished 16 wine yeast species: Hanseniaspora uvarum, H. valbyensis, H. opuntiae / H. uvarum, Lachancea thermotolerans, Candida tropicalis, Candida sp. / Starmerella sp., Metschnikowia pulcherrima, Pichia kudriavzevii, P. terricola, P. kluyveri, Wickerhamomyces anomalus, Kodamaea ohmeri, S. bacillaris, Saccharomyces cerevisiae, Saturnispora diversa and Torulaspora delbrueckii. We observed that obtained yeasts are common inhabitants of grape microflora, and that applied pest managament in studied vineyards had an influence on occurence of certain species. Thereafter, we tested yeasts for siderophore production, antifungal VOCs production, hydrolysis activity and yeast tolerance to fungicides like copper, iprodione, fluazinam and cyprodinil / fludioxonil combination. With a qualitative detection of the hydrolysis activity by using screening methods based on soild medium with chitin or β-D-glucosides as substrates, we recognized that many tested yeasts were able to produce lytic enzymes that could be responsible for cell wall degradation of phytopathogenic fungi, and potentially able to produce VOCs from the hydrolysis of grape glycosides due to the β-glucosidase presence. We also observed that these enzymatic activities are usually strain-dependent. In general yeasts were also tolerant to tested fungicides, and we concluded that fungicide resistance of biofungicide yeasts is beneficial trait for future biofungicide development for possible applications in low input pest management strategies.

Kemijske in senzorične lastnosti vina so poleg genetskih danosti ter geo-klimatskih okoliščin odvisne tudi od strategije tehnologije pridelave, ki jo izbere vinar. V to strategijo spada tudi izbira seva kvasovke. Vinski trg postaja vse bolj zahteven in željan nečesa novega, zato vse več vinarjev poskuša pridobiti drugačne lastnosti vin z uporabo drugačnih sevov kvasovk, oziroma z uporabo kombinacij različnih vrst kvasovk. V diplomski nalogi smo preučevali vpliv različnih kombinacij kvasovk na potek fermentacije ter na osnovne kemijske in senzorične lastnosti pridelanega jabolčnega vina. Poskus je bil izveden na laboratorijski skali. Rezultati poskusa so pokazali, da različne vrste kvasovk različno vplivajo na senzorične lastnosti vina, nekoliko manj pa na kemijske lastnosti. Rezultati nakazujejo, da različne kvasovke različno hitro porabljajo sladkorje, kar vpliva tudi na hitrost poteka fermentacije. Ob opazovanju osnovnih kemijskih lastnostih smo opazili razlike med kvasovkami oz. kombinacijami kvasovk pri parametrih kot so hlapne kisline in reducirajoči sladkorji, medtem ko v vsebnosti alkohola in pH vrednostih končnih jabolčnih vin med obravnavanimi fermentacijami nismo opazili razlik. Senzorična analiza vonja in barve jabolčnih vin je potrdila vpliv kvasovk na barvo, intenzivnost, trajnost in vrsto vonja. In addition to genetic predisposition and geo-climatic growing conditions, the chemical and sensory properties of wine depend also on the production strategies chosen by the winemaker. These strategies include the decisions on yeast strains used for the fermentation. The wine market is becoming increasingly demanding and often desires something new, therefore more and more winemakers are trying to acquire different properties of wines by using different strains of yeasts or combinations of different types of yeasts. In the diploma thesis we studied the influence of various yeast combinations on the course of fermentation and the basic chemical and sensory properties of the produced apple wine. The work was done on laboratory scale. The results indicated different types of yeasts to have stronger influence on sensory properties than on the observed chemical characteristics of the wine. We have found that various yeasts use sugars in a different manner and therefore the rate of fermentation is different. Within chemical properties, the biggest differences were found in the content of volatile acidity and reducing sugars, whereas the differences in pH and alcohol level were only minor. Sensory analysis confirmed the yeasts influence theon color, intensity, persistence and type of flavour.