Isolation and characterization of yeast strains from Badacsony, Hungary

In modern winery, starter strains are used for wine making to avoid the risk of slow or incomplete fermentation.However, application of commercial starter yeasts sometimes leads to a uniform character of the wines. On the other hand, indigenous (“terroir”) strains are adapted better to local conditions highlighting the specific taste of wine. In this study, we isolated local yeast strains from Badacsony wine region of Hungary and investigated with microbiological and molecular biological tests in order to develop indigenous starter selection method. As many as 480 yeast strains were isolated and grouped using carbohydrate and nitrogen sources. Finally, 80 selected isolates were characterized for important oenological features, including tolerance of glucose, ethanol and acetic acid. Fermentation ability, killer toxin, hydrogen sulfide and acid production of 80 selected isolates were also tested. Isolates were studied by applying two molecular methods based on rRNA gene sequencing and analysis of Ty retrotransposon's delta elements in case of Saccharomyces strains. Our results have shown that the isolated strains belong to 15 yeast species of 8 genera, and the diversity of yeast population was significantly high in the investigated vineyard. We have found that selection for technological properties was a potential way to find suitable strains from the local microbiome, because a high proportion of isolated wild yeast strains show beneficial oenological properties for wine making. Further, we studied 35 available starter yeasts to avoid re-isolation and we identified only 3 starter yeasts from grape and must samples, which can be considered as very low incidenc

Isolation and characterization of yeast strains from Badacsony, Hungary

461-473In modern winery, starter strains are used for wine making to avoid the risk of slow or incomplete fermentation. However, application of commercial starter yeasts sometimes leads to a uniform character of the wines. On the other hand, indigenous (“terroir”) strains are adapted better to local conditions highlighting the specific taste of wine. In this study, we isolated local yeast strains from Badacsony wine region of Hungary and investigated with microbiological and molecular biological tests in order to develop indigenous starter selection method. As many as 480 yeast strains were isolated and grouped using carbohydrate and nitrogen sources. Finally, 80 selected isolates were characterized for important oenological features, including tolerance of glucose, ethanol and acetic acid. Fermentation ability, killer toxin, hydrogen sulfide and acid production of 80 selected isolates were also tested. Isolates were studied by applying two molecular methods based on rRNA gene sequencing and analysis of Ty retrotransposon's delta elements in case of Saccharomyces strains. Our results have shown that the isolated strains belong to 15 yeast species of 8 genera, and the diversity of yeast population was significantly high in the investigated vineyard. We have found that selection for technological properties was a potential way to find suitable strains from the local microbiome, because a high proportion of isolated wild yeast strains show beneficial oenological properties for wine making. Further, we studied 35 available starter yeasts to avoid re-isolation and we identified only 3 starter yeasts from grape and must samples, which can be considered as very low incidence

Effect of sex ratios, spiking and extra artificial insemination on the breeding efficiency of broiler breeders

Since early fertility decline is a permanent problem of broiler breeders, the aim of this study was to test the effects of various sex ratios, spiking strategies and additional artificial inseminations (AI) on their breeding efficiency. Six breeder flocks were analysed during the whole reproduction cycle. In Flock A the sex ratio was maintained at 10% during the whole cycle (control), while in Flock B the number of males was increased to a final ratio of 16%. In Flocks C (technological control), D, E and F the ratio of males was gradually decreased from 10% to 6.5% until the end of the cycle. Moreover, at the age of 44 weeks in Flocks D and E 50 and 100% of cockerels were replaced by young ones, respectively, while in Flock F additional artificial inseminations were applied in the second half of the reproduction cycle. The increase of sperm transport was successful only in Groups B (increase in male numbers) and D (50% replacement of old cockerels with young ones); however, it was not sufficient for increasing the fertility rates in either group. Nor did additional artificial inseminations (Flock F) have an effect on fertility. As a conclusion, it can be established that increasing the sperm count in the hens’ oviducts in any way could not improve fertility in the last third of the production cycle. The results also suggest that the expensive and labour-intensive spiking technique used in broiler breeder management is useless. The prime factor responsible for the shortened persistence of fertility may be the reduced ability of the female oviduct to accept and store sperm

Clonal Selection of Autochthonous Grape Varieties in Badacsony, Hungary

As the sensitivity of perennial crops to climate change becomes more pronounced, clonal selection, which is already very time-consuming for grapevine, may take even longer, while its importance is increasing. In the case of indigenous grapevine varieties, the purpose of clonal selection is twofold: to mitigate problems of cultivation and at the same time, to preserve the varietal character. The cultivation technique issue of ‘Kéknyelű’ is the low fertility (functionally female-flowered variety), and as for ‘Juhfark’ it is the significant susceptibility to grey rot. Based on daily meteorological data of 11 years, the years were classified into 3 groups and harvest data were analyzed within each group. Significant difference in yield was found between clone B.2. and the base ‘Kéknyelű’. Both clones of ‘Kéknyelű’ matured with significantly lower pH compared to the base variety. Given the acidic character of ‘Kéknyelű’ wine and the predicted rise in must °Brix and pH as a result of climate change, these differences may be useful in the future. Botrytis infection only showed statistically significant differences between year groups for ‘Juhfark’. It is intriguing that in most years, the rate of grey rot infection was lower in both clones compared to the base variety, especially in year groups 1 and 3 when the overall rate of Botrytis infection was quite low

Characterization of Saccharomyces Strains Isolated from “Kéknyelű” Grape Must and Their Potential for Wine Production

Novel wine yeast strains have the potential to satisfy customer demand for new sensorial experiences and to ensure that wine producers have strains that can produce wine as efficiently as possible. In this respect, hybrid yeast strains have recently been the subject of intense research, as they are able to combine the favourable characteristics of both parental strains. In this study, two Saccharomyces “Kéknyelű” grape juice isolates were identified by species-specific PCR and PCR-RFLP methods and investigated with respect to their wine fermentation potential. Physiological characterization of the isolated strains was performed and included assessment of ethanol, sulphur dioxide, temperature and glucose (osmotic stress) tolerance, killer-toxin production, glucose fermentation ability at 16 °C and 24 °C, and laboratory-scale fermentation using sterile “Kéknyelű” must. Volatile components of the final product were studied by gas chromatography (GC) and mass spectrometry (MS). One isolate was identified as a S. cerevisiae × S. kudriavzevii hybrid and the other was S. cerevisiae. Both strains were characterized by high ethanol, sulphur dioxide and glucose tolerance, and the S. cerevisiae strain exhibited the killer phenotype. The hybrid isolate showed good glucose fermentation ability and achieved the lowest residual sugar content in wine. The ester production of the hybrid strain was high compared to the control S. cerevisiae starter strain, and this contributed to the fruity aroma of the wine. Both strains have good oenological characteristics, but only the hybrid yeast has the potential for use in wine fermentation.</p