Biology subjects

Saona, L. A.

Publications and source records attributed to Saona, L. A..

3 recordsLinked to original sources

bioRxiv2025

Transcriptional Reprogramming Drives Cold Adaptation During Long-Term Starvation in S. eubayanus

The ability of microorganisms to survive prolonged periods of nutrient scarcity is essential for their survival. Yet, the underlying adaptive mechanisms remain partly understood, especially in non-model eukaryotes. Here, we examined how the cryotolerant yeast Saccharomyces eubayanus adapts to 60 days of cold (4{degrees}C) starvation, focusing on the roles of genetic and transcriptional changes. We find that the primary engine of the long-term adaptation is a stable, reprogrammed transcriptional state, rather than the selection of point mutations. Aged isolates exhibited improved growth performance and cryotolerance, a phenotype that remained stable for [~]40 generations. This specialist adaptation involved a trade-off with tolerance to other stresses. Whole-genome sequencing revealed few fixed mutations, indicating that genetic variation did not drive the phenotype. Transcriptomic analysis revealed a significant physiological reprogramming, with cells shifting from anabolic activity to a catabolic, scavenging state driven by enhanced respiration and activation of the General Stress Response. This work highlights that a stable transcriptional state drives long-term cold adaptation, providing the foundation for the superior phenotype of aged isolates that persist through generations.

microbiology↗

bioRxiv2024

Understanding brewing trait inheritance in de novo lager yeast hybrids

Hybridization between Saccharomyces cerevisiae and Saccharomyces eubayanus resulted in the emergence of S. pastorianus, a crucial yeast for lager fermentation. However, our understanding of hybridization success and hybrid vigour between these two species remains limited due to the scarcity of S. eubayanus parental strains. Here, we explore hybridization success and the impact of hybridization on fermentation performance and volatile compound profiles in newly formed lager hybrids. By selecting parental candidates spanning a diverse array of lineages from both species, we reveal that the Beer and PB-2 lineages exhibit high rates of hybridization success in S. cerevisiae and S. eubayanus, respectively. Polyploid hybrids were generated through rare mating techniques, revealing a prevalence of triploids and diploids over tetraploids. Despite the absence of heterosis in fermentative capacity, hybrids displayed phenotypic variability, notably influenced by maltotriose consumption. Interestingly, ploidy levels did not significantly correlate with fermentative capacity, although triploids exhibited greater phenotypic variability. The S. cerevisiae parental lineages primarily influenced volatile compound profiles, with significant differences in aroma production. Interestingly, hybrids emerging from the Beer S. cerevisiae parental lineages exhibited a volatile compound profile resembling the corresponding S. eubayanus parent. This pattern may result from the dominant inheritance of the S. eubayanus aroma profile, as suggested by the over-expression of genes related to alcohol metabolism and acetate synthesis in hybrids including the Beer S. cerevisiae lineage. Our findings suggest complex interactions between parental lineages and hybridization outcomes, highlighting the potential for creating yeasts with distinct brewing traits through hybridization strategies.

microbiology↗

bioRxiv2019

Analysis of co-regulated abundance of genes associated with arsenic and phosphate metabolism in Andean Microbial Ecosystems

Phosphate and arsenate are very similar compounds, and there is great interest in studying their relationship and their interaction with biological systems. Despite having no apparent biological function, specific genes regulate arsenic interaction with cells and can be located in regions of the genome called arsenic islands, where phosphate metabolism genes are also present. Although they are neighboring genes, the nature of their relationship and how they have been selected is still unknown. In this work, we analyzed the metagenomes of the four microbial ecosystems inhabiting hypersaline lakes of the Argentine Puna and the Atacama salt flat in Chile and have evaluated the presence and abundance of both arsenic and phosphate metabolism genes. The samples analyzed included microbialites, biofilms and microbial mats; all of them established under high arsenic concentrations, high UV radiation and high temperature fluctuation, among others. The results show great differences in the dispersion and abundance of genes related to both phosphate and arsenic metabolism in the analyzed samples. The main difference is given in the Diamante Lake, located in the crater of the Galan volcano characterized by being one of the lakes with the highest arsenic concentration (2.34 mM). Correlating genes abundance with the physicochemical parameters of the lakes studied, our results suggest that arsenic and phosphate metabolism are intricately co-regulated in environmental conditions.

genomics↗