Aims: Saccharomyces cerevisiae is responsible for alcoholic fermentation of wines. However, some strains can also spoil sweet Botrytis-affected wines. Three 'refermentation' strains were isolated during maturation. Characterization of those strains in regards to their fingerprint, rDNA sequence and resistance to SO2, which constituted the main source of stress in Botrytis-affected wines, was carried out.
Methods And Results: Refermentation strains could be clearly discriminated by interdelta fingerprinting. However, they exhibited close relationships by karyotyping. A part of RDN1 locus sequence was examined by using PCR-RFLP and PCR-DGGE. The resistance of refermentation strains to SO2 was performed by using real time quantitative PCR focusing on SSU1 gene.
Conclusions: Results suggested that refermentation strains were heterozygote in 26S rDNA and their ITS1-5.8S rDNA-ITS2 region sequence revealed relationships with 'flor' strains. As described in the literature for flor strain, two out of three refermentation strains constitutively developed a higher level of SSU1 expression than the reference strains, improving their putative tolerance to SO2. Therefore, refermentation strains of S. cerevisiae had developed many strategies to survive during maturing sweet wines.
Significance And Impact Of The Study: Singularities in rDNA sequence and SSU1 overexpression revealed a natural adaptation. Moreover, genomic relationship between flor and refermentation strains suggested that stress sources could induced selection of survivor strains.
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http://dx.doi.org/10.1111/j.1365-2672.2005.02818.x | DOI Listing |
Food Chem
September 2024
Institute of Sciences of Food Production, National Research Council, Prov.le, Lecce-Monteroni, 73100 Lecce, Italy.
This research explored the impact of binary cereal blends [barley with durum wheat (DW) and soft wheat (CW)], four autochthonous yeast strains (9502, 9518, 14061 and 17290) and two refermentation sugar concentrations (6-9 g/L), on volatolomics (VOCs) and odour profiles of craft beers using unsupervised statistics. For the first time, we applied permutation test to select volatiles with higher significance in explaining variance among samples. The unsupervised approach on the 19 selected VOCs revealed cereal-yeast interaction to be the main source of variability and DW-9502-6/9, DW-17290-6, CW-17290-6 and CW-9518-6 being the best technological strategies.
View Article and Find Full Text PDFFoods
July 2023
Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnodai, Tsukuba 305-8572, Ibaraki, Japan.
Yeast and lactic acid bacteria (LAB) are known to play an important role in the fermentation process of coffee post-harvest. This study aimed to isolate and screen yeast and LAB to be applied in lab-scale refermentation of commercial green coffee beans and coffee pulp with the aim of modifying the composition of organic acids (OAs) in coffee beans. Yeast and LAB strains were isolated from green coffee beans and dry coffee pulp and identified, and their effect on OA concentration in the coffee beans was quantified.
View Article and Find Full Text PDFFood Chem
January 2023
VIB-KU Leuven Center for Microbiology, Leuven, Belgium; CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Leuven, Belgium; Leuven Institute for Beer Research, Leuven, Belgium. Electronic address:
Beer quality generally diminishes over time as staling compounds accumulate through various oxidation reactions. Here, we show that refermentation, a traditional practice where Saccharomyces cerevisiae cells are added to beer prior to bottling, diminishes the accumulation of staling aldehydes. However, commonly used beer yeasts only show a limited lifespan in beer.
View Article and Find Full Text PDFStud Mycol
June 2020
Helmholtz-Zentrum für Infektionsforschung GmbH, Department Microbial Drugs, Inhoffenstrasse 7, Braunschweig, 38124, Germany.
() is a large, cosmopolitan genus comprising over 130 species that have been defined based mainly on the morphology of their sexual morphs. The genus comprises both lignicolous and saprotrophic species that are frequently isolated as endophytes from healthy host plants, and important plant pathogens. In order to evaluate the utility of molecular phylogeny and secondary metabolite profiling to achieve a better basis for their classification, a set of strains was selected for a multi-locus phylogeny inferred from a combination of the sequences of the internal transcribed spacer region (ITS), the large subunit (LSU) of the nuclear rDNA, beta-tubulin () and the second largest subunit of the RNA polymerase II ().
View Article and Find Full Text PDFFront Microbiol
June 2017
Department of Food, Environmental and Nutritional Sciences, Università degli Studi di MilanoMilan, Italy.
The in-bottle fermentation of sparkling wines is currently triggered by few commercialized strains. This lack of diversity in yeast cultures leads to a prevalent uniformity in sensory profiles of the end products. The aim of this study has been to exploit the natural multiplicity of yeast populations in order to introduce variability in sparkling wines throughout the re-fermentation step.
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