Biology subjects

Albertin, W.

Publications and source records attributed to Albertin, W..

4 recordsLinked to original sources

bioRxiv2021

Different trajectories of polyploidization shape the genomic landscape of the Brettanomyces bruxellensis yeast species

Polyploidization events are observed across the tree of life and occurred in many fungi, plant and animal species. Polyploidy is thought to be an important source of speciation and tumorigenesis. However, the origins of polyploid populations are not always clear and little is known about the precise nature and structure of their complex genome. Using a long-read sequencing strategy, we sequenced a large number of isolates from the Brettanomyces bruxellensis yeast species, which is found in anthropized environments (e.g. beer, contaminant of wine, kombucha and ethanol production) and characterized by several polyploid subpopulations. To reconstruct the polyploid genomes, we phased them by using different strategies and we found that each subpopulation had a unique polyploidization history with distinct trajectories. The polyploid genomes contain either genetically closely related (with a genetic divergence < 1%) or diverged copies (> 3%), indicating auto- as well as allopolyploidization events. These latest events have occurred independently with a specific and unique donor in each of the polyploid subpopulations, and exclude the known Brettanomyces sister species as possible donors. Finally, loss of heterozygosity events have shaped the structure of these polyploid genomes and underline their dynamic. Overall, our study highlights the multiplicity of the trajectories leading to polyploid genomes within a same species.

genomics↗

bioRxiv2020

The SSU1 checkup, a rapid tool for detecting chromosomal rearrangements of the Saccharomyces cerevisiae chromosome XVI. An ecological and technological study on wine yeast.

1)Chromosomal rearrangements (CR) such as translocations, duplications and inversions play a decisive role in the adaptation of microorganisms to specific environments. In enological Saccharomyces cerevisiae strains, CR involving the promoter region of the gene SSU1 lead to a higher sulfite tolerance by enhancing the SO2 efflux. To date, three different SSU1 associated CR events have been described, including translocations XV-t-XVI and VIII-t-XVI and inversion inv-XVI. In the present study, we developed a multiplex PCR method (SSU1 check-up) that allows a rapid characterization of these three chromosomal configurations in a single experiment. Nearly 600 S. cerevisiae strains collected from fermented grape juice were genotyped by microsatellite markers. We demonstrated that alleles of the SSU1 promoter are differently distributed according to the wine environment (cellar versus vineyard) and the nature of the grape juice. Moreover, rearranged SSU1 promoters are significantly enriched among commercial starters. In addition, nearly isogenic strains collected in similar environments show different CR suggesting that translocation events occur with a non-negligible frequency in clonal populations likely due to mitotic recombination events. Finally, the link between the nature of SSU1 promoter and the tolerance to sulfite was statistically validated in natural grape juice containing various SO2 concentrations. The SSU1 check-up is therefore a convenient new tool for addressing population genetics questions and for selecting yeast strains by using molecular markers.

microbiology↗

bioRxiv2019

Brettanomyces bruxellensis wine isolates show high geographical dispersal and long remanence in cellars

Brettanomyces bruxellensis is the main wine spoiler yeast all over the world, yet the structuration of the populations associated with winemaking remains elusive. In this work, we considered 1411 wine isolates from 21 countries that were genotyped using twelve microsatellite markers. We confirmed that B. bruxellensis isolates from wine environments show high genetic diversity, with 58 and 42% of triploid and diploid individuals respectively distributed in 5 main genetic groups. The distribution in the genetic groups varied greatly depending on the country and/or the wine-producing region. However, the two wine triploid groups showing sulfite resistance/tolerance were identified in almost all regions/countries. Genetically identical isolates were also identified. The analysis of these clone groups revealed that a given genotype could be isolated repeatedly in the same winery over decades, demonstrating unsuspected remanence ability. Besides cellar residency, a great geographic dispersal was also evidenced, with some genotypes isolated in wines from different continents. Finally, the study of old isolates and/or isolates from old vintages revealed that only the diploid groups were identified prior 1990 vintages. The triploid groups were identified in subsequent vintages, and their proportion has increased steadily these last decades, suggesting adaptation to winemaking practices such as sulfite use. A possible evolutionary scenario explaining these results is discussed.

genetics↗

bioRxiv2019

Microbiological, biochemical, physicochemical surface properties and biofilm forming ability of Brettanomyces bruxellensis

Brettanomyces bruxellensis is a serious source of concern for winemakers. The production of volatile phenols by the yeast species confers to wine unpleasant sensory characteristics which are unacceptable by the consumers and inevitably provoke economic loss for the wine industry. This ubiquitous yeast is able to adapt to all winemaking steps and to withstand various environmental conditions. Moreover, the ability of B. bruxellensis to adhere and colonize inert materials can be the cause of the yeast persistence in the cellars and thus recurrent wine spoilage. We therefore investigated the surface properties, biofilm formation capacity and the factors which may affect the attachment of the yeast cells to surfaces with eight strains representative of the genetic diversity of the species. Our results show that the biofilm formation ability is strain-dependent and suggest a possible link between the physicochemical properties of the studied strains and their corresponding genetic group.

microbiology↗