Yeasts are common inhabitants of the phyllosphere, but our knowledge of their diversity in various plant organs is still limited. This study focused on the diversity of yeasts and yeast-like organisms associated with matured fruits and fully open blossoms of apple, plum, and pear trees, during 2 consecutive years at 3 localities in southwest Slovakia. The occurrence of yeasts and yeast-like organisms in fruit samples was 2½ times higher and the yeast community more diverse than that in blossom samples. Only 2 species (Aureobasidium pullulans and Metschnikowia pulcherrima) occurred regularly in the blossom samples, whereas Galactomyces candidus, Hanseniaspora guilliermondii, Hanseniaspora uvarum, M. pulcherrima, Pichia kluyveri, Pichia kudriavzevii, and Saccharomyces cerevisiae were the most frequently isolated species from the fruit samples. The ratio of the number of samples where only individual species were present to the number of samples where 2 or more species were found (consortium) was counted. The occurrence of individual species in comparison with consortia was much higher in blossom samples than in fruit samples. In the latter, consortia predominated. Aureobasidium pullulans, M. pulcherrima, and S. cerevisiae, isolated from both the fruits and blossoms, can be considered as resident yeast species of various fruit tree species cultivated in southwest Slovakia localities.
The yeasts were isolated from the leaf surfaces of ten species of trees. The study site was a forest park (Zelezná Studnicka) of the Small Carpathians mountain range. One hundred and thirty seven yeast strains belonging to 13 genera were isolated from 320 samples of leaves and needles. Seventeen yeast species were isolated, but only seven occurred regularly: Aureobasidium pullulans, Cryptococcus laurentii, Pichia anomala, Metschnikowia pulcherrima, Saccharomyces sp., Lachancea thermotolerans, and Rhodotorula glutinis. The remaining species were isolated from the leaves and needles of three or less tree species. A. pullulans, Cr. laurentii, and P. anomala were the most frequently found species and they occurred on leaves and needles of all ten tree species. Saccharomyces sp. occurred in leaf samples collected from eight kinds of trees. M. pulcherrima and L. thermotolerans were found in samples collected from six species of trees. Both these species occurred almost always on the leaves of deciduous trees. Rh. glutinis was the most frequently isolated carotenoids producing species. We have found out that the ascomycetous and basidiomycetous species were present in the leaf samples in approximately equal frequency, contrary to the soil samples taken from this forest park, where the ascomycetous species were found rarely.
Yeasts were isolated from leaf surfaces of five species of fruit trees located in southwest Slovakia. One hundred and fifty five yeast strains belonging to 11 genera were isolated from 300 samples of leaves. Seventeen yeast species were identified, but only three occurred regularly: Aureobasidium pullulans, Cryptococcus laurentii, and Metschnikowia pulcherrima. Species such as Hanseniaspora uvarum, Pichia anomala, Rhodotorula glutinis, and Saccharomyces cerevisiae, were isolated less frequently. We found only few differences in the yeast community isolated from leaves of different tree species although dominant species occurred regularly on the majority of leaves. Furthermore, yeast species varied throughout years. In spite of the fact that the yeast community occupying the leaves of the fruit trees was studied in the samples harvested in three localities, which are distanced from each other some kilometers, the qualitative representation of the most isolated yeasts was identical. The differences were only in the frequency of the incidence of individual species in the samples.
In the present work we isolated and identified various indigenous Saccharomyces cerevisiae strains and screened them for the selected oenological properties. These S. cerevisiae strains were isolated from berries and spontaneously fermented musts. The grape berries (Sauvignon blanc and Pinot noir) were grown under the integrated and organic mode of farming in the South Moravia (Czech Republic) wine region. Modern genotyping techniques such as PCR-fingerprinting and interdelta PCR typing were employed to differentiate among indigenous S. cerevisiae strains. This combination of the methods provides a rapid and relatively simple approach for identification of yeast of S. cerevisiae at strain level. In total, 120 isolates were identified and grouped by molecular approaches and 45 of the representative strains were tested for selected important oenological properties including ethanol, sulfur dioxide and osmotic stress tolerance, intensity of flocculation and desirable enzymatic activities. Their ability to produce and utilize acetic/malic acid was examined as well; in addition, H2S production as an undesirable property was screened. The oenological characteristics of indigenous isolates were compared to a commercially available S. cerevisiae BS6 strain, which is commonly used as the starter culture. Finally, some indigenous strains coming from organically treated grape berries were chosen for their promising oenological properties and these strains will be used as the starter culture, because application of a selected indigenous S. cerevisiae strain can enhance the regional character of the wines.
In enology, yeasts play an important role in the characteristics of the final product. They are predominant in the biochemical interaction with components of must. Rapid identification of the yeast population is necessary for fermentation process monitoring and for obtaining a good quality wine. The main goal of this study was the isolation and characterisation of the yeast microbial community naturally present on grape berries, leaves and occurring during the spontaneous fermentation process of the white wine Veltlin green from the South Moravian region, Czech Republic. The results, based on PCR-RFLP of the 5.8S-ITS region of rDNA, PCR-fingerprinting using microsatellite oligonucleotide primers (GAG)5, (GTG)5, (GAC)5, and M13 primer, showed great diversity of the yeast population. Including grape berries and fermented must, the following yeast species were identified: Hanseniaspora uvarum, Aureobasidium pullulans, Metschnikowia pulcherrima, Torulaspora delbrueckii, a number of Pichia species such as P. fermentans, P. membranifaciens, P. kluyveri, also Sporidiobolus salmonicolor, Rhodosporidium toruloides, Rhodotorula mucilaginosa, Rhodotorula glutinis as well as Saccharomyces cerevisiae and Saccharomyces bayanus. Monitoring of the yeast strains during the wine fermentation process of traditional Moravian wine can contribute to the improvement of wine quality.
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