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Biodiversity of cider yeasts and their cider-making potential
Lorena Butinar, Branka Mozetič Vodopivec, Melita Sternad Lemut, Eivind Vangdal, 2017, published scientific conference contribution abstract

Abstract: In the area of Hardanger, a part of the fjord region in Western Norway, the production of apple wine (cider) has a long tradition that goes back to the 12th century, when monks introduced apple growing in this area. Nowadays, this is also the main area of fruit production in Norway. Despite the strict regulation of the alcoholic beverage production in Norway, traditional cider is still produced on some farms in this area. By tradition cider is produced by a spontaneous fermentation process of apple juice, performed by naturally occurring indigenous yeasts that originate from the fruit or the surfaces of the processing equipment. Therefore, our aim was primarily to study the ecology and biodiversity of the yeasts associated with the production of traditional cider in the Hardanger area. For two consecutive years, we sampled at 11 different locations in the observed region, where we collected cider samples and surface swabs of processing facilities from the cideries, and also soil and various parts of apple trees in orchards owned by the same producers. Thus, by enriching collected samples with the selective medium with high sugar and ethanol concentration, we managed to isolate about 1,300 yeasts. Based on the multiplex PCR results the yeasts were grouped into the Saccharomyces sensu stricto complex and non-Saccharomyces yeasts. The isolates were determined to the species level by performing the restriction analysis of ITS PCR products, and in some cases identifications were confirmed by sequencing of the D1/D2 domain of the 26S rDNA and/ or ITS region. As expected, non-Saccharomyces yeasts from the genus Metschnikowia and Hanseniaspora mainly populated the orchards, while the Saccharomyces yeasts were isolated in the orchards from the soil and fruits. In contrast, in ciders the species S. uvarum was predominantly found, occasionally also S. cerevisiae, Torulaspora delbrueckii and P. membranifacies. Indigenous cider yeasts were further on characterized in micro-plate format for the most important cider-making technological parameters (tolerance to ethanol, SO2, growth at low pH), for the presence of glucoside hydrolase activity, H2S production ability, and assimilation of malic acid. Based on this screenings the micro-scale fermentations of apple juice were performed with 13 different indigenous cider yeasts as monocultures. The most promising indigenous yeasts, T. delbrueckii and S. uvarum, were also tested as mixed cultures in sequential fermentations. Since the tested strain of T. delbrueckii as monoculture was not able to complete the alcoholic fermentation, better results were obtained in sequential fermentation with the mixed culture in combination with S. uvarum.
Found in: osebi
Keywords: indigenous yeasts, biodiversity, spontaneous fermentation, cider-making
Published: 08.11.2017; Views: 2796; Downloads: 0
.pdf Fulltext (10,33 MB)

Study of yeast biodiversity potential in the development of biological control agents against phytopathogenic fungi in viticulture
Lorena Butinar, Urban Česnik, Adesida Rowland, Melita Sternad Lemut, 2017, published scientific conference contribution abstract

Abstract: Despite public’s growing concerns for human health and environmental pollution, synthetic fungicides are still preferred and massively used for the protection of agricultural crop plants against fungal diseases. However, more and more research is focused on finding potential alternatives in the form of effective biological control agents. Although there are reports of yeast’s biocontrol activity, they are up to date poorly commercialized for such purposes. As the yeasts represent an important part of the grape microflora, competing with other microorganisms (including pathogens) for nutrients and space, we decided to examine the potential of autochthonous yeasts as "green" alternatives in fighting against phytopathogens such as Botrytis cinerea in viticulture. With this aim we tested biocontrol activity of various strains / species of indigenous wine yeasts that were isolated from the vineyard environment in Slovenia and cross-border Italy. The yeasts were tested for the presence of siderophores, hydrolytic enzymes (chitinase, β-glucosidase and β-glucanase) and sensitivity to fungicides (copper, iprodion, cyprodinil + fludioxonil combination). The tests of phytopathogenic fungi growth inhibition in the presence of antagonistic yeast were also performed. The double Petri dish test was used to verify the inhibition of conidia germination by the formation of antifungal volatile organic compounds (VOC), synthetized by the antagonistic yeasts. The presence of hydrolytic enzymes was confirmed in many wine yeasts, particularly in the strains of Hanseniaspora uvarum and Metschnikowia pulcherrima species and in some strains of the Pichia genus. Using a medium, based on natural diluted grape juice in a double Petri dish test, we found that yeasts of the Debaryomyces hansenii, Lachancea thermotolerans, P. kudriavzevii, Saccharomyces kudriavzevii, S. cerevisiae and Torulaspora delbrueckii species were able to inhibit the germination of fungal conidia at the expense of the VOC formation. However, none of the up to date tested yeasts formed siderophores. On the other hand, the yeasts were generally resistant to the tested fungicide concentrations, thus they could be used as potential biofungicides in the combination with chemical fungicides.
Found in: osebi
Keywords: yeasts, biocontrol, Botrytis cinerea, viticulture
Published: 08.11.2017; Views: 2482; Downloads: 0
.pdf Fulltext (10,33 MB)

Eivind Vangdal, Melita Sternad Lemut, Branka Mozetič Vodopivec, Lorena Butinar, 2017, published scientific conference contribution abstract

Abstract: Na območju fjorda Hardanger, del zahodne Norveške, ima proizvodnja jabolčnega vina dolgo tradicijo in sicer sega v 12. stoletje, ko so menihi na tem območju začeli uvajati sadjarstvo. Danes je to glavno območje pridelovanja sadja na Norveškem. Kljub strogi regulativi proizvodnje alkoholnih pijač, pa se je na tem območju na nekaterih kmetijah ohranila tradicionalna proizvodnja jabolčnega vina. Namen naše študije je bil predvsem preučiti ekologijo in biotsko raznovrstnost kvasovk, ki so povezane s proizvodnjo tradicionalnega jabolčnega vina na območju Hardanger. Na tem območju smo tekom dveh zaporednih let vzorčili na 11-ih različnih lokacijah, kjer smo pri proizvajalcih vzorčili jabolčno vino, tla in različne dele jablan v sadovnjakih. Tako smo s pomočjo bogatitve v gojišču s povišanim sladkorjem in etanolom osamili približno 1300 izolatov kvasovk. Kvasovke smo s pomočjo multipleks PCR testa ločili na skupino kompleksa Saccharomyces sensu stricto in ne-Saccharomyces kvasovke. Nadalje smo izolate določili do nivoja vrste z izvedbo restrikcijske analize ITS PCR produktov, v nekaterih primerih smo za potrditev identifikacij opravili še določitev nukleotidnih zaporedij D1/D2 domene 26S rDNA. Kot pričakovano smo ugotovili, da sadovnjake naseljujejo predvsem ne-Saccharomyces kvasovke iz rodov Metschnikowia in Hanseniaspora, v tem okolju so bile Saccharomyces izolirane iz tal in jabolk. V jabolčnem vinu pa je bila pretežno izolirana vrsta S. uvarum, občasno pa tudi S. cerevisiae, Torulaspora delbrueckii in P. membranifacies.
Found in: osebi
Keywords: kvasovke, biotska raznovrstnost, jabolčno vino
Published: 09.11.2017; Views: 2606; Downloads: 0
.pdf Fulltext (334,39 KB)

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