Wine yeast species show strong inter- and intra-specific variability in their sensitivity to ultraviolet radiation

Yeast UPS1 deficiency leads to UVC radiation sensitivity and shortened lifespan

UPS1/YLR193C of Saccharomyces cerevisiae (S. cerevisiae) encodes a mitochondrial intermembrane space protein. A previous study found that Ups1p is needed for normal mitochondrial morphology and that UPS1 deficiency disrupts the intramitochondrial transport of phosphatidic acid in yeast cells and leads to an altered unfolded protein response and mTORC1 signaling activation. In this paper, we first provide evidence showing that the UPS1 gene is involved in the UVC-induced DNA damage response and aging. We show that UPS1 deficiency leads to sensitivity to ultraviolet C (UVC) radiation and that this effect is accompanied by elevated DNA damage, increased intracellular ROS levels, abnormal mitochondrial respiratory function, an increased early apoptosis rate, and shortened replicative lifespan and chronological lifespan. Moreover, we show that overexpression of the DNA damage-induced checkpoint gene RAD9 effectively eliminates the senescence-related defects observed in the UPS1-deficient strain. Collectively, these results suggest a novel role for UPS1 in the UVC-induced DNA damage response and aging.

Brettanomyces bruxellensis: Overview of the genetic and phenotypic diversity of an anthropized yeast

Human-associated microorganisms are ideal models to study the impact of environmental changes on species evolution and adaptation because of their small genome, short generation time, and their colonization of contrasting and ever-changing ecological niches. The yeast Brettanomyces bruxellensis is a good example of organism facing anthropogenic-driven selective pressures. It is associated with fermentation processes in which it can be considered either as a spoiler (e.g. winemaking, bioethanol production) or as a beneficial microorganism (e.g. production of specific beers, kombucha). Besides its industrial interests, noteworthy parallels and dichotomies with Saccharomyces cerevisiae propelled B. bruxellensis as a valuable complementary yeast model. In this review, we emphasize that the broad genetic and phenotypic diversity of this species is only beginning to be uncovered. Population genomic studies have revealed the co-existence of auto- and allotriploidization events with different evolutionary outcomes. The different diploid, autotriploid and allotriploid subpopulations are associated with specific fermented processes, suggesting independent adaptation events to anthropized environments. Phenotypically, B. bruxellensis is renowned for its ability to metabolize a wide variety of carbon and nitrogen sources, which may explain its ability to colonize already fermented environments showing low-nutrient contents. Several traits of interest could be related to adaptation to human activities (e.g. nitrate metabolization in bioethanol production, resistance to sulphite treatments in winemaking). However, phenotypic traits are insufficiently studied in view of the great genomic diversity of the species. Future work will have to take into account strains of varied substrates, geographical origins as well as displaying different ploidy levels to improve our understanding of an anthropized yeast's phenotypic landscape.