Quantitative Assessment of Volatile Profile and Sensory Perception of Artisan Bread Made in the City of Valencia.

Artisan bread, known for its simple recipes, natural ingredients, and traditional techniques, has seen a surge in demand, especially following the COVID-19 pandemic. Small bakeries emphasize extended fermentation processes and prioritize sensory qualities in their products. However, the impact of ingredients on the quality characteristics of artisan bread remains underexplored.

Sourdough Yeast Strains Exhibit Thermal Tolerance, High Fermentative Performance, and a Distinctive Aromatic Profile in Beer Wort.

The increasing popularity of home brewing and the fast evolution of craft beer companies have fuelled the interest in novel yeasts as the main actors diversifying the beer portfolio. Here, we have characterized the thermal tolerance and brewing-related features of two sourdough (SD) isolates of , SDy01 and SDy02, at different temperatures, 20 and 37 °C, comparing them with commercial brew strains, AaB and kNB. The SD strains exhibited tolerance to the main brewing-related stress conditions and increased growth rates and lower lag phases than the reference beer strains at both temperatures.

Bioprospecting of sourdough microbial species from artisan bakeries in the city of Valencia.

This work describes the characterization of an artisanal sourdough set of bakeries located in the city of Valencia. Culture-dependent and -independent analyses detected Fructilactobacillus sanfranciscensis, Saccharomyces cerevisiae and Kazachstania humilis as dominant species. Nevertheless, specific technological parameters, including backslopping temperature, dough yield, or the addition of salt affected microbial counting, LAB/Yeast ratio, and gassing performance, favouring the appearance of several species of Lactobacillus sp.

Adaptive laboratory evolution for acetic acid-tolerance matches sourdough challenges with yeast phenotypes.

Acetic acid tolerance of Saccharomyces cerevisiae is an important trait in sourdough fermentation processes, where the accumulation of acid by the growth of lactic acid bacteria reduces the yeast metabolic activity. In this work, we have carried out adaptive laboratory evolution (ALE) experiments in two sourdough isolates of S. cerevisiae exposed to acetic acid, or alternatively to acetic acid and myriocin, an inhibitor of sphingolipid biosynthesis that sped-up the evolutionary adaptation.

Slt2 Is Required to Activate ER-Stress-Protective Mechanisms through TORC1 Inhibition and Hexosamine Pathway Activation.

Slt2, the MAPK of the cell wall integrity (CWI) pathway, connects different signaling pathways and performs different functions in the protective response of to stress. Previous work has evidenced the relation of the CWI pathway and the unfolded protein response (UPR), a transcriptional program activated upon endoplasmic reticulum (ER) stress. However, the mechanisms of crosstalk between these pathways and the targets regulated by Slt2 under ER stress remain unclear.

Sphingolipids and Inositol Phosphates Regulate the Tau Protein Phosphorylation Status in Humanized Yeast.

Hyperphosphorylation of protein tau is a hallmark of Alzheimer's disease (AD). Changes in energy and lipid metabolism have been correlated with the late onset of this neurological disorder. However, it is uncertain if metabolic dysregulation is a consequence of AD or one of the initiating factors of AD pathophysiology.

Myriocin-induced adaptive laboratory evolution of an industrial strain of Saccharomyces cerevisiae reveals its potential to remodel lipid composition and heat tolerance.

The modification of lipid composition allows cells to adjust membrane biophysical properties in response to changes in environmental temperature. Here, we use adaptive laboratory evolution (ALE) in the presence of myriocin, a sphingolipid (SLs) biosynthesis inhibitor, to remodel the lipid profile of an industrial yeast strain (LH) of Saccharomyces cerevisiae. The approach enabled to obtain a heterogeneous population (LHev) of myriocin-tolerant evolved clones characterized by its growth capacity at high temperature.

Hexose transport in Torulaspora delbrueckii: identification of Igt1, a new dual-affinity transporter.

Torulaspora delbrueckii is a yeast species receiving increasing attention from the biotechnology industry, with particular relevance in the wine, beer and baking sectors. However, little is known about its sugar transporters and sugar transport capacity, frequently a rate-limiting step of sugar metabolism and efficient fermentation. Actually, only one glucose transporter, Lgt1, has been characterized so far.

The formation of hybrid complexes between isoenzymes of glyceraldehyde-3-phosphate dehydrogenase regulates its aggregation state, the glycolytic activity and sphingolipid status in Saccharomyces cerevisiae.

The glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been traditionally considered a housekeeping protein involved in energy generation. However, evidence indicates that GAPDHs from different origins are tightly regulated and that this regulation may be on the basis of glycolysis-related and glycolysis-unrelated functions. In Saccharomyces cerevisiae, Tdh3 is the main GAPDH, although two other isoenzymes encoded by TDH1 and TDH2 have been identified.

Pho85 and PI(4,5)P regulate different lipid metabolic pathways in response to cold.

Lipid homeostasis allows cells to adjust membrane biophysical properties in response to changes in environmental conditions. In the yeast Saccharomyces cerevisiae, a downward shift in temperature from an optimal reduces membrane fluidity, which triggers a lipid remodeling of the plasma membrane. How changes in membrane fluidity are perceived, and how the abundance and composition of different lipid classes is properly balanced, remain largely unknown.

The Antarctic yeast Candida sake: Understanding cold metabolism impact on wine.

Current winemaking trends include low-temperature fermentations and using non-Saccharomyces yeasts as the most promising tools to produce lower alcohol and increased aromatic complexity wines. Here we explored the oenological attributes of a C. sake strain, H14Cs, isolated in the sub-Antarctic region.

Inappropriate translation inhibition and P-body formation cause cold-sensitivity in tryptophan-auxotroph yeast mutants.

In response to different adverse conditions, most eukaryotic organisms, including Saccharomyces cerevisiae, downregulate protein synthesis through the phosphorylation of eIF2α (eukaryotic initiation factor 2α) by Gcn2, a highly conserved protein kinase. Gcn2 also controls the translation of Gcn4, a transcription factor involved in the induction of amino acid biosynthesis enzymes. Here, we have studied the functional role of Gcn2 and Gcn2-regulating proteins, in controlling translation during temperature downshifts of TRP1 and trp1 yeast cells.

Sng1 associates with Nce102 to regulate the yeast Pkh-Ypk signalling module in response to sphingolipid status.

All cells are delimited by biological membranes, which are consequently a primary target of stress-induced damage. Cold alters membrane functionality by decreasing lipid fluidity and the activity of membrane proteins. In Saccharomyces cerevisiae, evidence links sphingolipid homeostasis and membrane phospholipid asymmetry to the activity of the Ypk1/2 proteins, the yeast orthologous of the mammalian SGK1-3 kinases.

Near-freezing effects on the proteome of industrial yeast strains of Saccharomyces cerevisiae.

At near-freezing temperatures (0-4°C), the growth of the yeast Saccharomyces cerevisiae stops or is severely limited, and viability decreases. Under these conditions, yeast cells trigger a biochemical response, in which trehalose and glycerol accumulate and protect them against severe cold and freeze injury. However, the mechanisms that allow yeast cells to sustain this response have been not clarified.

Characterization of the S. cerevisiae inp51 mutant links phosphatidylinositol 4,5-bisphosphate levels with lipid content, membrane fluidity and cold growth.

Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and its derivatives diphosphoinositol phosphates (DPIPs) play key signaling and regulatory roles. However, a direct function of these molecules in lipid and membrane homeostasis remains obscure. Here, we have studied the cold tolerance phenotype of yeast cells lacking the Inp51-mediated phosphoinositide-5-phosphatase.

Redox engineering by ectopic expression of glutamate dehydrogenase genes links NADPH availability and NADH oxidation with cold growth in Saccharomyces cerevisiae.

Background: Cold stress reduces microbial growth and metabolism being relevant in industrial processes like wine making and brewing. Knowledge on the cold transcriptional response of Saccharomyces cerevisiae suggests the need of a proper redox balance. Nevertheless, there are no direct evidence of the links between NAD(P) levels and cold growth and how engineering of enzymatic reactions requiring NAD(P) may be used to modify the performance of industrial strains at low temperature.

Nuclear versus cytosolic activity of the yeast Hog1 MAP kinase in response to osmotic and tunicamycin-induced ER stress.

We examined the physiological significance of the nuclear versus cytosolic localization of the MAPK Hog1p in the ability of yeast cells to cope with osmotic and ER (endoplasmic reticulum) stress. Our results indicate that nuclear import of Hog1p is not critical for osmoadaptation. Plasma membrane-anchored Hog1p is still able to induce increased expression of GPD1 and glycerol accumulation.

Protein kinase Snf1 is involved in the proper regulation of the unfolded protein response in Saccharomyces cerevisiae.

Glc7 is the only catalytic subunit of the protein phosphatase type 1 in the yeast S. cerevisiae and, together with its regulatory subunits, is involved in many essential processes. Analysis of the non-essential mutants in the regulatory subunits of Glc7 revealed that the lack of Reg1, and no other subunit, causes hypersensitivity to unfolded protein response (UPR)-inducers, which was concomitant with an augmented UPR element-dependent transcriptional response.

Genetic and phenotypic characteristics of baker's yeast: relevance to baking.

Yeasts rarely encounter ideal physiological conditions during their industrial life span; therefore, their ability to adapt to changing conditions determines their usefulness and applicability. This is especially true for baking strains of Saccharomyces cerevisiae. The success of this yeast in the ancient art of bread making is based on its capacity to rapidly transform carbohydrates into CO2 rather than its unusual resistance to environmental stresses.

Low temperature highlights the functional role of the cell wall integrity pathway in the regulation of growth in Saccharomyces cerevisiae.

Unlike other stresses, the physiological significance and molecular mechanisms involved in the yeast cold response are largely unknown. In the present study, we show that the CWI (cell wall integrity) pathway plays an important role in the growth of Saccharomyces cerevisiae at low temperatures. Cells lacking the Wsc1p (wall integrity and stress response component 1) membrane sensor or the MAPKs (mitogen-activated protein kinases) Bck1p (bypass of C kinase 1), Mkk (Mapk kinase) 1p/Mkk2p or Slt2p (suppressor of lyt2) exhibited cold sensitivity.

Multicopy suppression screening of Saccharomyces cerevisiae Identifies the ubiquitination machinery as a main target for improving growth at low temperatures.

A decrease in ambient temperature alters membrane functionality and impairs the proper interaction between the cell and its external milieu. Understanding how cells adapt membrane properties and modulate the activity of membrane-associated proteins is therefore of major interest from both the basic and the applied points of view. Here, we have isolated multicopy suppressors of the cold sensitivity phenotype of a trp1 strain of Saccharomyces cerevisiae.

Adaptive evolution of baker's yeast in a dough-like environment enhances freeze and salinity tolerance.

We used adaptive evolution to improve freeze tolerance of industrial baker's yeast. Our hypothesis was that adaptation to low temperature is accompanied by enhanced resistance of yeast to freezing. Based on this hypothesis, yeast was propagated in a flour-free liquid dough model system, which contained sorbitol and NaCl, by successive batch refreshments maintained constantly at 12°C over at least 200 generations.

Isolation and characterization of the carbon catabolite-derepressing protein kinase Snf1 from the stress tolerant yeast Torulaspora delbrueckii.

We cloned a genomic DNA fragment of the yeast Torulaspora delbrueckii by complementation of a Saccharomyces cerevisiae snf1Δ mutant strain. DNA sequence analysis revealed that the fragment contained a complete open reading frame (ORF), which shares a high similarity with the S. cerevisiae energy sensor protein kinase Snf1.

Global expression studies in baker's yeast reveal target genes for the improvement of industrially-relevant traits: the cases of CAF16 and ORC2.

Background: Recent years have seen a huge growth in the market of industrial yeasts with the need for strains affording better performance or to be used in new applications. Stress tolerance of commercial Saccharomyces cerevisiae yeasts is, without doubt, a trait that needs improving. Such trait is, however, complex, and therefore only in-depth knowledge of their biochemical, physiological and genetic principles can help us to define improvement strategies and to identify the key factors for strain selection.

The activity of yeast Hog1 MAPK is required during endoplasmic reticulum stress induced by tunicamycin exposure.

Accumulation of unfolded proteins in the endoplasmic reticulum (ER) triggers the so-called unfolded protein response (UPR), a conserved signaling pathway that drives the transcription of genes such as chaperones and folding enzymes. Nevertheless, the activity of the UPR accounts only for a part of the gene expression program activated upon ER stress. Moreover, the mechanism(s) for how cells adapt and survive to this stress are largely unknown.