Yeast Saccharomyces Cerevisiae Research Articles

The ‘Erlenmeter’: a low-cost, open-source turbidimeter for no-sampling phenotyping of microorganism growth

This work presents a low-cost, open-source turbidimeter, the ‘Erlenmeter’, designed to monitor the growth of microorganisms in batch cultures. It is easy to build, based exclusively on inexpensive off-the-shelf electronic components and 3D-printed parts. The Erlenmeter allows measuring the optical density of cultures on standard Erlenmeyer flasks without the need to open the flasks to collect aliquots, ensuring speed, minimal use of consumables, and elimination of the risk of contamination. These features make it particularly well-suited not just for routine research assays but also for experimental teaching. Here we illustrate the use of the Erlenmeter turbidimeter to record the growth of the microalga Phaeodactylum tricornutum, of the bacterium Escherichia coli, and of the yeast Saccharomyces cerevisiae, model organisms that are widely used in research and teaching. The Erlenmeter allows a detailed characterization of the growth curves of all organisms, confirming its usefulness for studying microbial populations dynamics both for research purposes and in classroom settings.

An APEX2-based proximity-dependent biotinylation assay with temporal specificity to study protein interactions during autophagy in the yeast Saccharomyces cerevisiae

ABSTRACT Autophagosome biogenesis is a complex process orchestrated by dynamic interactions between Atg (autophagy-related) proteins and characterized by the turnover of specific cargoes, which can differ over time and depending on how autophagy is stimulated. Proteomic analyses are central to uncover protein-protein interaction networks and when combined with proximity-dependent biotinylation or proximity labeling (PL) approaches, they also permit to detect transient and weak interactions. However, current PL procedures for yeast Saccharomyces cerevisiae, one of the leading models for the study of autophagy, do not allow to keep temporal specificity and thus identify interactions and cargoes at a precise time point upon autophagy induction. Here, we present a new ascorbate peroxidase 2 (APEX2)-based PL protocol adapted to yeast that preserves temporal specificity and allows uncovering neighbor proteins by either western blot or proteomics. As a proof of concept, we applied this new method to identify Atg8 and Atg9 interactors and detected known binding partners as well as potential uncharacterized ones in rich and nitrogen starvation conditions. Also, as a proof of concept, we confirmed the spatial proximity interaction between Atg8 and Faa1. We believe that this protocol will be a new important experimental tool for all those researchers studying the mechanism and roles of autophagy in yeast, but also other cellular pathways in this model organism. Abbreviations: APEX2, ascorbate peroxidase 2, Atg, autophagy-related; BP, biotin phenol; Cvt, cytoplasm-to-vacuole targeting; ER, endoplasmic reticulum; LN2, liquid nitrogen; MS, mass spectrometry; PAS, phagophore assembly site; PL, proximity labeling; PE, phosphatidylethanolamine; PPINs, protein-protein interaction networks; PPIs, protein-protein interactions; RT, room temperature; SARs, selective autophagy receptors; WT, wild-type.

Natural variation in yeast reveals multiple paths for acquiring higher stress resistance

BackgroundOrganisms frequently experience environmental stresses that occur in predictable patterns and combinations. For wild Saccharomyces cerevisiae yeast growing in natural environments, cells may experience high osmotic stress when they first enter broken fruit, followed by high ethanol levels during fermentation, and then finally high levels of oxidative stress resulting from respiration of ethanol. Yeast have adapted to these patterns by evolving sophisticated “cross protection” mechanisms, where mild ‘primary’ doses of one stress can enhance tolerance to severe doses of a different ‘secondary’ stress. For example, in many yeast strains, mild osmotic or mild ethanol stresses cross protect against severe oxidative stress, which likely reflects an anticipatory response important for high fitness in nature.ResultsDuring the course of genetic mapping studies aimed at understanding the mechanisms underlying natural variation in ethanol-induced cross protection against H2O2, we found that a key H2O2 scavenging enzyme, cytosolic catalase T (Ctt1p), was absolutely essential for cross protection in a wild oak strain. This suggested the absence of other compensatory mechanisms for acquiring H2O2 resistance in that strain background under those conditions. In this study, we found surprising heterogeneity across diverse yeast strains in whether CTT1 function was fully necessary for acquired H2O2 resistance. Some strains exhibited partial dispensability of CTT1 when ethanol and/or salt were used as mild stressors, suggesting that compensatory peroxidases may play a role in acquired stress resistance in certain genetic backgrounds. We leveraged global transcriptional responses to ethanol and salt stresses in strains with different levels of CTT1 dispensability, allowing us to identify possible regulators of these alternative peroxidases and acquired stress resistance in general.ConclusionsUltimately, this study highlights how superficially similar traits can have different underlying molecular foundations and provides a framework for understanding the diversity and regulation of stress defense mechanisms.

Identification of the cytochrome P450s responsible for the biosynthesis of two types of aporphine alkaloids and their de novo biosynthesis in yeast.

Aporphine alkaloids have diverse pharmacological activities; however, our understanding of their biosynthesis is relatively limited. Previous studies have classified aporphine alkaloids into two categories based on the configuration and number of substituents of the D-ring and have proposed preliminary biosynthetic pathways for each category. In this study, we identified two specific cytochrome P450 enzymes (CYP80G6 and CYP80Q5) with distinct activities toward (S)-configured and (R)-configured substrates from the herbaceous perennial vine Stephania tetrandra, shedding light on the biosynthetic mechanisms and stereochemical features of these two aporphine alkaloid categories. Additionally, we characterized two CYP719C enzymes (CYP719C3 and CYP719C4) that catalyzed the formation of the methylenedioxy bridge, an essential pharmacophoric group, on the A- and D-rings, respectively, of aporphine alkaloids. Leveraging the functional characterization of these crucial cytochrome P450 enzymes, we reconstructed the biosynthetic pathways for the two types of aporphine alkaloids in budding yeast (Saccharomyces cerevisiae) for the de novo production of compounds such as (R)-glaziovine, (S)-glaziovine, and magnoflorine. This study provides key insight into the biosynthesis of aporphine alkaloids and lays a foundation for producing these valuable compounds through synthetic biology.

Construcción de plásmidos mediante clonación in vivo para la búsqueda y caracterización de oligopéptidos quelantes de hierro en <i>Saccharomyces cerevisiae</i>

Saccharomyces cerevisiae yeast serves as a nutritional supplement and food additive that may offer highly bioavailable iron. Several studies have demonstrated the viability of using iron-chelating oligopeptides to treat anaemia, suggesting that their production in yeast cells could advantageously provide an easy-to-use supplement. In this study, an in vivo cloning strategy was optimized to construct a semi-random plasmid library that enables the production of oligopeptides with six repetitions of Asp/Glu-Asp/Glu-Leu sequences. In these sequences, the first and second positions can include either aspartate or glutamate residues, while the third is always leucine. Additionally, several plasmids were constructed to allow the study of variants of the Arg-Glu-Glu oligopeptide, previously reported as an iron chelator. In each case, the required plasmid constructions were performed using an in vivo cloning strategy in S. cerevisiae, based on gap repair by homologous recombination. The procedure involves the co-transformation of yeast cells with the linearized plasmid and the fragment to be cloned, both with homologous flanking sequences. The resulting transformants harbor the correctly assembled plasmids and begin expressing the cloned genes, thereby enabling immediate analysis of the synthesized oligopeptides with known or semi-random sequences.

Intensification of high-gravity brewer’s wort fermentation process with the use of microelements

In high-gravity brewing, conditions arise that adversely affect the yeast. These are high osmotic pressure, high fermentation temperature, high ethanol content. As a result of these unfavorable factors, the intensity of yeast reproduction and the rate of fermentation decrease, the duration of the process increases, the degree of fermentation decreases, which leads to a change in the taste and aroma profile of the drink. Cofactors of important enzymes and stress modulators are microelement ions, the optimal content of which can be provided by adding appropriate salts to the wort. In this work, the influence of calcium and zinc on the fermentation of high-gravity beer wort with the participation of Saccharomyces cerevisiae yeast strain Saflager W-34/70 was investigated. The optimal dosage of CaCl2 and ZnSO4 salts was determined, which is 5.0 and 0.1 mg/dm3, respectively. It was established that adding CaCl2 to the wort leads to an increase in the rate of fermentation by 21.9 %, the apparent and actual degree of fermentation by 17.8 and 17.0 %, respectively. At the same time, the ethanol content in young beer increases by 19.1 %, the content of visible and actual extract decreases by 28.8 and 17.5 %, respectively, and the biomass of yeast accumulated during fermentation increases by 14.0 %. When using ZnSO4, the changes in the values of all these indicators are significantly smaller and lie in the range of 3.2‒5.8 %. Other physical-chemical parameters of the studied samples of young beer, namely acidity, pH value, content of vicinal diketones, do not undergo significant changes. To enhance the growth and metabolism of yeast under adverse conditions that occur during high-gravity brewing, it is recommended to add CaCl2 to beer wort in the amount of 5.0 mg/dm3. This will make it possible to reduce the duration of fermentation of wort with a dry matter content of 18 % at a temperature of 15 ℃ by 1.5 days (21 %)

Effect of Treating Date Peels with Different Levels of Yeast (Saccharomyces cerevisiae) on Some Fermentations of Rumen Fluid in Vitro

Effect of Treating Date Peels with Different Levels of Yeast (Saccharomyces cerevisiae) on Some Fermentations of Rumen Fluid in Vitro

DsRNA formation leads to preferential nuclear export and gene expression

When mRNAs have been transcribed and processed in the nucleus, they are exported to the cytoplasm for translation. This export is mediated by the export receptor heterodimer Mex67–Mtr2 in the yeast Saccharomyces cerevisiae (TAP–p15 in humans)1,2. Interestingly, many long non-coding RNAs (lncRNAs) also leave the nucleus but it is currently unclear why they move to the cytoplasm3. Here we show that antisense RNAs (asRNAs) accelerate mRNA export by annealing with their sense counterparts through the helicase Dbp2. These double-stranded RNAs (dsRNAs) dominate export compared with single-stranded RNAs (ssRNAs) because they have a higher capacity and affinity for the export receptor Mex67. In this way, asRNAs boost gene expression, which is beneficial for cells. This is particularly important when the expression program changes. Consequently, the degradation of dsRNA, or the prevention of its formation, is toxic for cells. This mechanism illuminates the general cellular occurrence of asRNAs and explains their nuclear export.

Comparison of Xrn1 and Rat1 5' → 3' exoribonucleases in budding yeast supports the specific role of Xrn1 in cotranslational mRNA decay.

The yeast Saccharomyces cerevisiae and most eukaryotes carry two 5' → 3' exoribonuclease paralogs. In yeast, they are called Xrn1, which shuttles between the nucleus and the cytoplasm, and executes major cytoplasmic messenger RNA (mRNA) decay, and Rat1, which carries a strong nuclear localization sequence (NLS) and localizes to the nucleus. Xrn1 is 30% identical to Rat1 but has an extra ~500 amino acids C-terminal extension. In the cytoplasm, Xrn1 can degrade decapped mRNAs during the last round of translation by ribosomes, a process referred to as "cotranslational mRNA decay." The division of labor between the two enzymes is still enigmatic and serves as a paradigm for the subfunctionalization of many other paralogs. Here we show that Rat1 is capable of functioning in cytoplasmic mRNA decay, provided that Rat1 remains cytoplasmic due to its NLS disruption (cRat1). This indicates that the physical segregation of the two paralogs plays roles in their specific functions. However, reversing segregation is not sufficient to fully complement the Xrn1 function. Specifically, cRat1 can partially restore the cell volume, mRNA stability, the proliferation rate, and 5' → 3' decay alterations that characterize xrn1Δ cells. Nevertheless, cotranslational decay is only slightly complemented by cRat1. The use of the AlphaFold prediction for cRat1 and its subsequent docking with the ribosome complex and the sequence conservation between cRat1 and Xrn1 suggest that the tight interaction with the ribosome observed for Xrn1 is not maintained in cRat1. Adding the Xrn1 C-terminal domain to Rat1 does not improve phenotypes, which indicates that lack of the C-terminal is not responsible for partial complementation. Overall, during evolution, it appears that the two paralogs have acquired specific characteristics to make functional partitioning beneficial.

The MAPK homolog, Smk1, promotes assembly of the glucan layer of the spore wall in S. cerevisiae.

Smk1 is a MAPK homolog in the yeast Saccharomyces cerevisiae that controls the postmeiotic program of spore wall assembly. During this program, haploid cells are surrounded by a layer of mannan and then a layer of glucan. These inner layers of the spore wall resemble the vegetative cell wall. Next, the outer layers consisting of chitin/chitosan and then dityrosine are assembled. The outer layers are spore-specific and provide protection against environmental stressors. Smk1 is required for the proper assembly of spore walls. However, the protective properties of the outer layers have limited our understanding of how Smk1 controls this morphogenetic program. Mutants lacking the chitin deacetylases, Cda1 and Cda2, form spores that lack the outer layers of the spore wall. In this study, cda1,2∆ cells were used to demonstrate that Smk1 promotes deposition of the glucan layer of the spore wall through the partially redundant glucan synthases Gsc2 and Fks3. Although Gsc2 is localized to sites of spore wall assembly in the wild type, it is mislocalized in the mother cell cytoplasm in the smk1∆ mutant. These findings suggest that Smk1 controls assembly of the spore wall by regulating the localization of Gsc2 during sporogenesis.

The limit to evolutionary rescue depends on ploidy in yeast exposed to nystatin.

The number of copies of each chromosome, or ploidy, of an organism is a major genomic factor affecting adaptation. We set out to determine how ploidy can impact the outcome of evolution, as well as the likelihood of evolutionary rescue, using short-term experiments with yeast (Saccharomyces cerevisiae) in a high concentration of the fungicide nystatin. In similar experiments using haploid yeast, the genetic changes underlying evolutionary rescue were highly repeatable, with all rescued lines containing a single mutation in the ergosterol biosynthetic pathway. All of these beneficial mutations were recessive, which led to the expectation that diploids would find alternative genetic routes to adaptation. To test this, we repeated the experiment using both haploid and diploid strains and found that diploid populations did not evolve resistance. Although diploids are able to adapt at the same rate as haploids to a lower, not fully inhibitory, concentration of nystatin, the present study suggests that diploids are limited in their ability to adapt to an inhibitory concentration of nystatin, while haploids may undergo evolutionary rescue. These results demonstrate that ploidy can tip the balance between adaptation and extinction when organisms face an extreme environmental change.

Two glycosyl transferase 2 genes from the gram-positive bacterium Clostridium ventriculi encode (1,3;1,4)-β-D-glucan synthases

The exopolysaccharides of the Gram-positive bacterium Romboutsia ilealis have recently been shown to include (1,3;1,4)-β-D-glucans. In the present study, we examined another Clostridia bacterium Clostridium ventriculi that has long been considered to contain abundant amounts of cellulose in its exopolysaccharides. We treated alcohol insoluble residues of C. ventriculi that include the exopolysaccharides with the enzyme lichenase that specifically hydrolyses (1,3;1,4)-β-D-glucans, and examined the oligosaccharides released. This showed the presence of (1,3;1,4)-β-D-glucans, which may have previously been mistaken for cellulose. Through genomic analysis, we identified the two family 2 glycosyltransferase genes CvGT2–1 and CvGT2–2 as possible genes encoding (1,3;1,4)-β-D-glucan synthases. Gain-of-function experiments in the yeast Saccharomyces cerevisiae demonstrated that both of these genes do indeed encode (1,3;1,4)-β-D-glucan synthases.

Evaluation of In-vitro Anti-Inflammatory, Anti-Fungal, Thrombolytic, Membrane Stabilizing and Cytotoxic Properties of (Camellia chrysantha Hu Tuyama)

The current study was set out to look into the anti-inflammatory, anti-fungal, cytotoxic, thrombolytic and membrane stabilizing activities of the methanolic extract from the leaf of Camellia chrysantha (Hu) Tuyama (MECCL). Primary evaluation of MECCL was performed via phytochemical screening. Phytochemical analysis of the leaf extract revealed the presence of reducing sugar, flavonoids, alkaloids, and steroids. Anti-inflammatory activity test was done using egg albumin denaturation assay. In the result of MECCL’s anti-inflammatory test showed 88.88% compared to the standard acetyl salicylic acid 98.56%. The anti-fungal activity test was performed by Disc Diffusion method using zone of inhibition against four fungi. MECCL showed moderate antifungal activity compared to standard Griseofulvin against Aspergillus niger, Saccharomyces cerevisiae (yeast), Penicillium notatum. Zones of inhibition of the fungi Aspergillus niger, Saccharomyces cerevisiae (yeast), Penicillium notatum is 11mm, 14mm and 14mm at the concentration of 700 µg/disc, which is close to the standard Griseofulvin 19mm, 20mm, and 21mm respectively at 50 µg/disc concentration. Mucor hiemalis showed mild zone of inhibition in 300, 500, and 700 µg/disc (7mm). Brine Shrimp lethality bioassay method was used to test the lethality of the methanolic leaf extract. The extract showed significant cytotoxic activity against brine shrimp nauplii with LC50 value of 0.843 µg/mL when compared with the standard Vincristine sulphate (LC50 value: 0.608 µg/mL). Comparison with positive control Vincristine sulphate signifies that cytotoxicity exhibited by MECCL and further bioactivity guided investigation can be done to find potent antitumor compounds. In thrombolytic activity test, MECCL demonstrated 95.69% thrombolysis which was significant compared to standard Streptokinase (SK) which demonstrated 91.304 % thrombolysis. While doing membrane stabilizing activity test, Heat induced hemolysis assay was performed and the percent of protection was 85.35 compared to the standard DS 73.63 which was very significant. The results highlight the potential of Camellia chrysantha (Hu) Tuyama as a valuable source of phytochemicals that possess notable anti-inflammatory, thrombolytic, and membrane-stabilizing properties. The methanolic leaf extract also shows moderate antifungal and cytotoxic effects, suggesting potential for future therapeutic advancements.

Induction of point and structural mutations in engineered yeast Saccharomyces cerevisiae improve carotenoid production.

β-Carotene is an attractive compound and that its biotechnological production can be achieved by using engineered Saccharomyces cerevisiae. In a previous study, we developed a technique for the efficient establishment of diverse mutants through the introduction of point and structural mutations into the yeast genome. In this study, we aimed to improve β-carotene production by applying this mutagenesis technique to S. cerevisiae strain that had been genetically engineered for β-carotene production. Point and structural mutations were introduced into β-carotene-producing engineered yeast. The resulting mutants showed higher β-carotene production capacity than the parental strain. The top-performing mutant, HP100_74, produced 37.6mg/L of β-carotene, a value 1.9 times higher than that of the parental strain (20.1mg/L). Gene expression analysis confirmed an increased expression of multiple genes in the glycolysis, mevalonate, and β-carotene synthesis pathways. In contrast, expression of ERG9, which functions in the ergosterol pathway competing with β-carotene production, was decreased in the mutant strain. The introduction of point and structural mutations represents a simple yet effective method for achieving mutagenesis in yeasts. This technique is expected to be widely applied in the future to produce chemicals via metabolic engineering of S. cerevisiae.

The plant rhabdovirus viroporin P9 facilitates insect-mediated virus transmission in barley.

Potassium (K+) plays crucial roles in both plant development and immunity. However, the function of K+ in plant-virus interactions remains largely unknown. Here, we utilized Barley yellow striate mosaic virus (BYSMV), an insect-transmitted plant cytorhabdovirus, to investigate the interplay between viral infection and plant K+ homeostasis. The BYSMV accessory P9 protein exhibits viroporin activity by enhancing membrane permeability in Escherichia coli. Additionally, P9 increases K+ uptake in yeast (Saccharomyces cerevisiae) cells, which is disrupted by a point mutation of Glycine 14 to Threonine (P9G14T). Furthermore, BYSMV P9 forms oligomers and targets to both the viral envelope and the plant membrane. Based on the recombinant BYSMV-green fluorescent protein (BYGFP) virus, a P9-deleted mutant (BYGFPΔP9) was rescued and demonstrated infectivity within individual plant cells of Nicotiana benthamiana and insect vectors. However, BYGFPΔP9 failed to infect barley plants after transmission by insect vectors. Furthermore, infection of barley plants was severely impaired for BYGFP-P9G14T lacking P9 K+ channel activity. In vitro assays demonstrate that K+ facilitates virion disassembly and the release of genome RNA for viral mRNA transcription. Altogether, our results show that the K+ channel activity of viroporins is conserved in plant cytorhabdoviruses and plays crucial roles in insect-mediated virus transmission.

Pre-adaptation of yeast (Saccharomyces cerevisiae) strains to very high gravity can improve fermentation parameters and reduce osmotic stress

Pre-adaptation of yeast (Saccharomyces cerevisiae) strains to very high gravity can improve fermentation parameters and reduce osmotic stress

Antioxidant inactivated yeast: High potential of non-Saccharomyces specific metabolome

Understanding the contribution of new natural sources of antioxidant compounds to the stability of wines is of great interest in a context of reduction of sulfites. Here, we investigated the antioxidant potential of selected inactivated non-Saccharomyces yeast (INSY) along with related chemical fingerprints, using combined untargeted UHPLC-Q-ToF MS and DPPH analyses. 4 INSY species were compared to a reference inactivated Saccharomyces cerevisiae yeast (ISY) selected for its high antioxidant capacity. Our results show that, all the INSY can accumulate GSH during the specific production process with yields ranging from +170 % to +360 % compared to the corresponding classical production process. The principal component analysis of the 3511 ions detected by UHPLC-Q-ToF-MS clearly grouped INSY by species, independently of the production process. One INSY exhibited equivalent antioxidant capacity to the control ISY, but with a GSH concentration four times lower (4.73 ± 0.09 mg/g against 20.95 ± 0.34 mg/g, respectively). 73 specific ions presenting strong and significant spearman correlation (rho < −0.6, p-value < 0.05) with the DPPH scores, clustered the most antioxidant INSY and the control Saccharomyces in different groups, indicating that the antioxidant capacity of these two products should be driven by different pools of compounds. These results point out that, GSH alone is not relevant to explain the antioxidant capacity of INSY soluble fractions and other more reactive compounds must be considered, which opens an avenue for the selection new species with great enological potential.

Chemical composition and biological activity of essential oil from anise hyssop

Anise hyssop (Agastache foeniculum (Pursh) Kuntze) is a perennial plant belonging to the Lamiaceae family mainly used in folk medicine to treat various ailments. This study determined the chemical composition of the essential oil and evaluated its antimicrobial and antioxidant activity. The essential oil was obtained from plants cultivated in the experimental field at the Institute of Roses, Essential and Medical Plants, Kazanlak, Bulgaria. The plants were processed by steam distillation, with the essential oil yielding 0.37%, and its main components being methyl chavicol (82.03%) and limonene (9.90%). The most potent antimicrobial action was observed against the gram-positive bacteria Staphylococcus aureus (25.7 mm inhibition zone) and Bacillus cereus (12.3 mm), the yeast Saccharomyces cerevisiae (16.3 mm) and Candida albicans (16.5 mm). The remaining gram-positive bacteria (Staphylococcus epidermidis and Bacillus subtilis), gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Salmonella ebony), and fungi (Aspergillus brasiliensis and Fusarium moniliforme) were resistant to the action of the essential oil. The antioxidant activity of the essential oil was ABTS (32.36 µmol TE/mL), DPPH (21.61 µmol TE/mL), CUPRAC (19.94 µmol TE/mL), and FRAP (29.56 µmol TE/mL) in vitro. Overall, the results from this study revealed the biological potential of anise hyssop as a source in pharmaceutical, food, and cosmetic applications.

Expression of human RECQL5 in Saccharomyces cerevisiae causes transcription defects and transcription-associated genome instability

RECQL5 is a member of the conserved RecQ family of DNA helicases involved in the maintenance of genome stability that is specifically found in higher eukaryotes and associates with the elongating RNA polymerase II. To expand our understanding of its function we expressed human RECQL5 in the yeast Saccharomyces cerevisiae, which does not have a RECQL5 ortholog. We found that RECQL5 expression leads to cell growth inhibition, increased genotoxic sensitivity and transcription-associated hyperrecombination. Chromatin immunoprecipitation and transcriptomic analysis of yeast cells expressing human RECQL5 shows that this is recruited to transcribed genes and although it causes only a weak impact on gene expression, in particular at G + C-rich genes, it leads to a transcription termination defect detected as readthrough transcription. The data indicate that the interaction between RNAPII and RECQL5 is conserved from yeast to humans. Unexpectedly, however, the RECQL5-ID mutant, previously shown to have reduced the association with RNAPII in vitro, associates with the transcribing polymerase in cells. As a result, expression of RECQL5-ID leads to similar although weaker phenotypes than wild-type RECQL5 that could be transcription-mediated. Altogether, the data suggests that RECQL5 has the intrinsic ability to function in transcription-dependent and independent genome dynamics in S. cerevisiae.

Bioprospecting and Selection of Indigenous Saccharomyces cerevisiae Yeasts from Pozo de Los Algarrobos (Argentina) for the Production of Genuine White Wines

Yeasts play a crucial role in the winemaking process contributing to the typicity and originality of wines in a region. Therefore, the aim of the present study was to isolate, characterize, and select yeasts from the Geographical Indication “Pozo de Los Algarrobos”, San Juan, Argentina. Yeasts were directly isolated from grapes and at different stages of spontaneous fermentations of Vitis vinifera Viognier and Chardonnay varieties. Molecular and intraspecific identification of Saccharomyces cerevisiae yeasts was conducted using the D1/D2 domain and interdelta, respectively, observing 13 different yeast strains from Viognier and 12 from Chardonnay vinifications. Based on the enological traits assayed, two strains, V22 (Viognier) and C14 (Chardonnay), were selected for further studies. Microvinifications with these yeasts were carried out with Viognier and Chardonnay grape must in 2 L flasks, and the resulting wines were analytically and sensorially evaluated. Overall, strain V22 produced wines with positive and particular sensory properties, associated with fruity and floral aromas, color intensity, sweetness, aromatic persistence, and varietal typicity. Consequently, biomass propagation of V22 was conducted to inoculate pilot- (100 L) and industrial (12,000 L)-scale fermentations. V22 resulted in a correct wine fermentation performance obtaining a final product with distinctive and genuine properties.