Yeast Research Articles

Human anti-apoptotic Bcl-2 and Bcl-xL proteins protect yeast cells from aging induced oxidative stress

Aging is a degenerative, biological, and time-dependent process that affects all organisms. Yeast aging is a physiological phenomenon characterized by the progressive transformation of yeast cells, resulting in modifications to their viability and vitality. Aging in yeast cells is comparable to that in higher organisms in some respects; however, due to their straightforward and well-characterized genetic makeup, these cells present unique advantages when it comes to researching the aging process. Here, we assessed the impact of human anti-apoptotic Bcl-2 and Bcl-xL proteins on aging using a yeast model. The findings clearly showed that these proteins exhibited remarkable anti-aging properties in yeast cells. Our data indicate that the presence of both proteins enhanced the reproductive survival of aging cells, likely by effecting the components functioning as both pro- and anti-oxidants, depending on the stage of yeast cell lifespan. Both proteins partially protected yeast cells from aging-related morphological deformations and cellular damage during the aging period. In particular, Bcl-xL expressing yeast cells reached the maximum activity levels for almost all of the major antioxidant enzymes and the total antioxidant status on the 8th day of lifespan and could provide effective protection at the latest stage of the investigated aging period. The chemometric data analysis of IR spectra confirmed the findings of the morphological and biochemical analyses. In this regard, specifically, understanding the mechanism of action on the cellular redox state of Bcl-xL in yeast may facilitate comprehension of its indirect antioxidant function in higher eukaryotes.

Targeting protein aggregation using a cocoa-bean shell extract to reduce α-synuclein toxicity in models of Parkinson's disease

Neurodegenerative diseases are among the major challenges in modern medicine, due to the progressive aging of the world population. Among these, Parkinson's disease (PD) affects 10 million people worldwide and is associated with the aggregation of the presynaptic protein α-synuclein (α-syn). Here we use two different PD models, yeast cells and neuroblastoma cells overexpressing α-syn, to investigate the protective effect of an extract from the cocoa shell, which is a by-product of the roasting process of cocoa beans. The LC-ESI-qTOF-MS and NMR analyses allow the identification of amino acids (including the essential ones), organic acids, lactate and glycerol, confirming also the presence of the two methylxanthines, namely caffeine and theobromine. The present study demonstrates that the supplementation with the cocoa bean shell extract (CBSE) strongly improves the longevity of yeast cells expressing α-syn, reducing the level of reactive oxygen species, activating autophagy and reducing the intracellular protein aggresomes. These anti-aggregation properties are confirmed also in neuroblastoma cells, where CBSE treatment leads to activation of AMPK kinase and to a significant reduction of toxic α-syn oligomers. Results obtained by surface plasmon resonance (SPR) assay highlights that CBSE binds α-syn protein in a concentration-dependent manner, supporting its inhibitory role on the amyloid aggregation of α-syn. These findings suggest that the supplementation with CBSE in the form of nutraceuticals may represent a promising way to prevent neurodegenerative diseases associated with α-syn aggregation.

Enzymatic oxidation of polyethylene by Galleria mellonella intestinal cytochrome P450s

Polyethylene is widely used but highly resistant to biodegradation, owing to its composition of only a hydrocarbon backbone. For biodegradation to occur, oxidation within the polymer needs to be initiated. Galleria mellonella was the first insect discovered to autonomously oxidize polyethylene without the aid of gut microbes. However, the specific enzyme remains unidentified. Here, we identified for the first time two polyethylene oxidation enzyme candidates of cytochrome P450 (CYP), 6B2-GP04 and CYP6B2-13G08, from the G. mellonella midgut. Both candidate clones oxidized polyethylene efficiently, generating short-chain aliphatic compounds, with CYP6B2-GP04 exhibiting higher activity than CYP6B2-13G08 in yeast and insect cells. In silico structural modeling approaches revealed that the CYP6B2-GP04 Phe118 was essential for interacting with hydrocarbons, which was further validated by mutating it to glycine. Furthermore, directed enzyme evolution led to the identification of an enzyme variant with significantly increased oxidation efficiency. Our findings offer promising enzyme-based solutions for polyethylene biodegradation, potentially mitigating polyethylene-driven plastic pollution.

From grass to yeast; functional insights from heterologous expression of LfHKT2;1 in ion regulation

Saccharomyces cervisceae mutants lacking the major potassium trasnporters trk1 and trk2 show hypersensitivity to aminoglycoside antibiotic hygromycin (hyg). This study demonstrates that expression of the inward K+ transporter LfHKT2;1 can suppress this hygromycin sensitivity in the trk1, trk2 double mutant strain. Growth complementation was performed on solid yeast peptone dextrose (YPD) media supplemented with hygromycin B. Both, wild type and trk1 trk2 yeast strains exhibited growth inhibition in the presence of hygromycin. However the potassium uptake-deficient trk1 trk2 strain (control) showed complete growth arrest when exposed to hygromycin, while expression of LfHKT2;1 resulted in growth recovery. Increased sodium concentrations caused cellular toxicity in the trk1 trk2 strain, which was exacerbated by the addition of hygromycin to the media. The hypersensitivity of trk1 trk2 mutant yeast cells expressing LfHKT2;1 to sodium suggested the presence of an additional sodium uptake system on the membrane, which was further confirmed by transient GFP expression assays. These results provide conclusive evidence that heterologous expression of LfHKT2;1 confers both sodium and K+ uptake capabilities in hygromycin supplemented YPD media, thereby rescuing the growth of K+ transport-deficient S. cerevisiae mutants. This highlights the potential of plant gene expression in yeast as a valuable tool for studying ion transport mechanisms and gene function under stress conditions.

Curcumin-loaded lignin nanoparticles: Exploring sonication effects on drug loading and particle properties for future biomedical use

The present study investigates the effects of sonication and cross-linker (oxalic acid) concentration on drug loading and the properties of curcumin-loaded lignin nanoparticles. Selected samples were further assessed for their toxicity and antioxidant potential using the eukaryotic model organism Saccharomyces cerevisiae. Transmission electron microscopy analyses revealed the formation of spherical nanoparticles with diameters in the range of 39–49 nm. Differential scanning calorimetry experiments confirmed the encapsulation of curcumin. Factorial experimental design analyses indicated that sonication time, wave amplitude, cross-linker concentration, and their interactions significantly influenced both ζ-potential – from (−37.0 ± 1.7) mV to (−48.4 ± 0.6) mV – and curcumin loading – from (3.70 ± 0.32) % to (7.10 ± 0.57) %. These parameters are critical for biomedical applications as they relate to the clearance of nanoparticles from the human bloodstream and drug dosage optimization. Although sonication has been previously reported for the preparation of lignin nanoparticles, this study represents the first documented instance of manipulating drug loading by controlled sonication parameters. While none of the investigated factors significantly affected the mean particle diameter, observations from TEM micrographs suggest that cross-linker concentration and wave amplitude notably influence nanoparticle morphology. Moreover, the curcumin-loaded nanoparticles exhibited non-toxicity toward Saccharomyces cerevisiae and demonstrated the ability to enhance yeast cell tolerance to H2O2-induced oxidative stress, underscoring their antioxidant potential. Therefore, this research significantly contributes to the scientific understanding of how the control of sonication parameters and cross-linkers can modulate the properties of curcumin-loaded lignin nanoparticles for future biomedical applications.

Transcriptional Downregulation of Methanol Metabolism Key Genes During Yeast Death in Engineered Pichia pastoris.

Pichia pastoris possesses the unique ability to utilize methanol as its sole carbon source, which makes it a proper host for producing various high-value-added products via metabolic engineering. Nevertheless, cell death has been observed during the fermentation of modified P. pastoris, with limited literature elucidating the underlying causes and mechanisms. Understanding the death mechanisms during methanol-based fermentation is crucial for optimizing fermentation strategies, enhancing the accumulation of target products, and reducing production costs. Here, we first sought to eliminate the potential causes of cell death during fermentation, such as inadequate inorganic salts and toxic by-product accumulation. The elimination of these potential causes was achieved efficiently utilizing the high-throughput fermentation equipment. Subsequently, we established a correlation between yeast cell death and the duration of the methanol metabolism period by monitoring the growth of the yeast at different fermentation stages. A critical revelation from this work came from analyzing the yeast's transcriptomic data at various stages of methanol metabolism. It was observed that a significant characteristic of yeast cell death during fermentation was the marked down-regulation of transcript levels of key enzymes involved in the methanol assimilation pathway and genes related to their biosynthesis process. The findings of this work are crucial for better understanding the causes and mechanisms of cell death for engineered P. pastoris during methanol-utilized fermentation.

Aloe ferox leaf gel extracts attenuate redox imbalance in oxidative renal injury and stimulates glucose uptake, whilst inhibiting key enzymes linked to diabetes and obesity

The worldwide prevalence of diabetes and obesity is growing rapidly. Both metabolic disorders are linked to chronic adverse complications, which include kidney dysfunctions. Medicinal plants play a crucial role in traditional healthcare, especially in developing countries. Aloe ferox, native to South Africa, has a long history of medicinal use, but its pharmacological potential is less studied compared to other Aloe species, necessitating further investigation. Therefore, the present study was conducted to determine the antioxidative, anti-obesogenic, and antidiabetic effects of A. ferox leaf gel extracts using in vitro, ex vivo, and in silico experimental models, with oxidative renal damage induced by ferrous sulfate (FeSO4). A. ferox leaf gel extracts exhibited strong antioxidant activity, inhibited digestive enzymes, and significantly improved glucose uptake. The aqueous extract demonstrated better antioxidant efficacy, leading to higher reduced glutathione (GSH) level, and superoxide dismutase (SOD) and catalase enzymes activity, along with a concurrent reduction of nitric oxide (NO) and malondialdehyde (MDA) levels. Likewise, the aqueous extract showed more potent in vitro DPPH, NO, and OH• radical scavenging activity with IC50 values of 3.64 ±0.3 μg/mL, 110.73±0.1 μg/mL, and 331.13 ±0.7 μg/mL, respectively. The aqueous extract had better inhibition of the enzyme α-amylase (IC50 = 25.73±2.5 µg/mL), whilst the ethanolic extract inhibited α-glucosidase (IC50 =663.2±0.3 µg/ml), and pancreatic lipase (IC50 =122.01±5.9 µg/mL) more strongly. Incubation of the extracts with yeast cells stimulated glucose uptake dose dependently, when ethanolic extract (IC50 = 308.01±0.7 µg/mL) showed the better activity compared to the aqueous extract (IC50 = 338.79±7.05 µg/mL). Furthermore, LC-MS analysis led to the identification of many compounds, when chlorogenic acid demonstrated a stronger molecular interaction with the active site amino acids of α-amylase and catalase compared to other compounds. However, Aloin B showed the highest affinity with α-glucosidase and 5-Hydroxyaloin A showed the lowest binding energy with lipase, and SOD enzyme. These results suggest the reno-protective effects of A. ferox leaf gel extracts against FeSO4-induced oxidative stress along with its anti-hyperglycaemic activity. Given these observed effects, A. ferox leaf gel could indeed be valuable in developing natural therapies and potential drug development for the management of these disorders. Further studies in animal models are needed to ascertain the results of this study.

Yeast cell wall-derived proteins: Identification and characterization as food emulsifiers

Emulsification activity has been identified in the cell wall mannoproteins of Saccharomyces cerevisiae—which is widely utilized in food products—and their applications have been explored. However, apart from Gas proteins, no other emulsifying cell wall proteins have been identified. A comprehensive understanding of the cell wall proteins involved in emulsification is crucial for advancing their applications. Herein, emulsifying proteins easily released from the cell wall, unlike Gas proteins that are covalently attached, were purified and characterized. Consequently, fructose 1,6-bisphosphate aldolase 1 (Fba1), Enolase (Eno) 1, and Eno2 showed emulsifying activity, and Fba1 had the highest activity. These are glycolytic proteins localized in the cytoplasm and cell wall. Because Triose-phosphate dehydrogenase (glyceraldehyde-3-phosphate dehydrogenase) 2 (Tdh2)—another glycolytic protein—is also localized in the cell wall, its emulsifying ability was investigated. Results indicated that Tdh2 also had strong activity and was comparable to the activity of casein, an emulsifier. Moreover, Tdh2 displayed higher emulsifying activity with 14 and 16 carbon hydrocarbons and stabilized emulsions in soybean oil. Tdh2—with a smaller molecular weight and nearly absent sugar chains compared to Gas proteins—holds promise for investigating the relationship between protein structure and emulsification. This study identified new emulsifying proteins localized to the cell wall through mechanisms other than covalent bonding. In addition, these proteins have potential applications as yeast-derived emulsifiers.

Study of impacts of two types of cellular aging on the yeast bud morphogenesis.

Understanding the mechanisms of the cellular aging processes is crucial for attempting to extend organismal lifespan and for studying age-related degenerative diseases. Yeast cells divide through budding, providing a classical biological model for studying cellular aging. With their powerful genetics, relatively short cell cycle, and well-established signaling pathways also found in animals, yeast cells offer valuable insights into the aging process. Recent experiments suggested the existence of two aging modes in yeast characterized by nucleolar and mitochondrial declines, respectively. By analyzing experimental data, this study shows that cells evolving into those two aging modes behave differently when they are young. While buds grow linearly in both modes, cells that consistently generate spherical buds throughout their lifespan demonstrate greater efficacy in controlling bud size and growth rate at young ages. A three-dimensional multiscale chemical-mechanical model was developed and used to suggest and test hypothesized impacts of aging on bud morphogenesis. Experimentally calibrated model simulations showed that during the early stage of budding, tubular bud shape in one aging mode could be generated by locally inserting new materials at the bud tip, a process guided by the polarized Cdc42 signal. Furthermore, the aspect ratio of the tubular bud could be stabilized during the late stage as observed in experiments in this work. The model simulation results suggest that the localization of new cell surface material insertion, regulated by chemical signal polarization, could be weakened due to cellular aging in yeast and other cell types, leading to the change and stabilization of the bud aspect ratio.

The 5-Fluorouracil RNA Expression Viewer (5-FUR) Facilitates Interpreting the Effects of Drug Treatment and RRP6 Deletion on the Transcriptional Landscape in Yeast.

Saccharomyces cerevisiae is an excellent model to study the effect of external cues on cell division and stress response. 5-Fluorocuracil (5-FU) has been used to treat solid tumors since several decades. The drug was initially designed to interfere with DNA replication but was later found to exert its antiproliferative effect also via RNA-dependent processes. Since 5-FU inhibits the activity of the 3'-5'-exoribonuclease Rrp6 in yeast and mammals, earlier work has compared the effect of 5-FU treatment and RRP6 deletion at the transcriptome level in diploid synchronized yeast cells. To facilitate interpreting the expression data we have developed an improved 5-Fluorouracil RNA (5-FUR) expression viewer. Users can access information via genome coordinates and systematic or standard names for mRNAs and Xrn1-dependent-, stable-, cryptic-, and meiotic unannotated transcripts (XUTs, SUTs, CUTs, and MUTs). Normalized log2-transformed or linear data can be displayed as filled diagrams, line graphs or color-coded heatmaps. The expression data are useful for researchers interested in processes such as cell cycle regulation, mitotic repression of meiotic genes, the effect of 5-FU treatment and Rrp6 deficiency on the transcriptome and expression profiles of sense/antisense loci that encode overlapping transcripts. The viewer is accessible at http://5fur.genouest.org.

Effects of passion fruit peel (Passiflora edulis) pectin and red yeast (Sporodiobolus pararoseus) cells on growth, immunity, intestinal morphology, gene expression, and gut microbiota in Nile tilapia (Oreochromis niloticus)

This study explores the effects of dietary supplementation with passion fruit peel pectin (Passiflora edulis) and red yeast cell walls (Sporidiobolus pararoseus) on growth performance, immunity, intestinal morphology, gene expression, and gut microbiota of Nile tilapia (Oreochromis niloticus). Nile tilapia with an initial body weight of approximately 15 ± 0.06 g were fed four isonitrogenous (29.09–29.94%), isolipidic (3.01–4.28%), and isoenergetic (4119–4214 Cal/g) diets containing 0 g kg−1 pectin or red yeast cell walls (T1 - Control), 10 g kg−1 pectin (T2), 10 g kg−1 red yeast (T3), and a combination of 10 g kg−1 pectin and 10 g kg−1 red yeast (T4) for 8 weeks. Growth rates and immune responses were assessed at 4 and 8 weeks, while histology, relative immune and antioxidant gene expression, and gut microbiota analysis were conducted after 8 weeks of feeding. The results showed that the combined supplementation (T4) significantly enhanced growth performance metrics, including final weight, weight gain, specific growth rate, and feed conversion ratio, particularly by week 8, compared to T1, T2, and T3 (P < 0.05). Immunological assessments revealed increased lysozyme and peroxidase activities in both skin mucus and serum, with the T4 group showing the most pronounced improvements. Additionally, antioxidant and immune-related gene expression, including glutathione peroxidase (GPX), glutathione reductase (GSR), and interleukin-1 (IL1), were upregulated in the gut, while intestinal morphology exhibited improved villus height and width. Gut microbiota analysis indicated increased alpha and beta diversity, with a notable rise in beneficial phyla such as Actinobacteriota and Firmicutes in the supplemented groups. These findings suggest that the combined use of pectin and red yeast cell walls as prebiotics in aquaculture can enhance the health and growth of Nile tilapia, offering a promising alternative to traditional practices. Further research is needed to determine optimal dosages for maximizing these benefits.

Recent Challenges in Diagnosis and Treatment of Invasive Candidiasis in Neonates.

Invasive Candida infections represent a significant cause of morbidity and mortality in the neonatal intensive care unit (NICU), particularly among preterm and low birth weight neonates. The nonspecific clinical presentation of invasive candidiasis, resembling that of bacterial sepsis with multiorgan involvement, makes the diagnosis challenging. Given the atypical clinical presentation and the potential detrimental effects of delayed treatment, empirical treatment is often initiated in cases with high clinical suspicion. This underscores the need to develop alternative laboratory methods other than cultures, which are known to have low sensitivity and a prolonged detection time, to optimize therapeutic strategies. Serum biomarkers, including mannan antigen/anti-mannan antibody and 1,3-β-D-glucan (BDG), both components of the yeast cell wall, a nano-diagnostic method utilizing T2 magnetic resonance, and Candida DNA detection by PCR-based techniques have been investigated as adjuncts to body fluid cultures and have shown promising results in improving diagnostic efficacy and shortening detection time in neonatal populations. This review aims to provide an overview of the diagnostic tools and the current management strategies for invasive candidiasis in neonates. Timely and accurate diagnosis followed by targeted antifungal treatment can significantly improve the survival and outcome of neonates affected by Candida species.

Optimization of transformation conditions of the yeast &lt;i&gt;Saccharomyces cerevisiae&lt;/i&gt; to determine coregulators of the transcription factor NIN in a yeast two-hybrid system

BACKGROUND: The method of protein-protein interaction analysis using the yeast two-hybrid system in Saccharomyces cerevisiae cells is used to search for protein coregulators. This method is also used for mass screening of libraries of cloned fragments of complementary DNA (cDNA) that are translated in the cell. The key factor in the success of such screening is the level of efficiency of yeast cell transformation, since the resolution of the analysis is based on this. AIM: The aim of this study is to search for optimal parameters for chemical transformation of yeast cells to increase the resolution of cDNA library screening. MATERIALS AND METHODS: Plasmids pDEST22 and pDEST32 were used for chemical transformation of the yeast strain S. cerevisiae pJ69-4A. For screening, a cDNA library was used, obtained on the basis of mRNA isolated from the roots of pea Pisum sativum cultivar Finale, inoculated with rhizobia. RESULTS: Factors influencing the efficiency of transformation were identified. Among them are the molecular weight of polyethyleneglycol used for transformation, as well as the number of cell division cycles that the culture undergoes. The effect of the number and size of plasmids used in transformation was also shown. Using the optimized protocol, a cDNA library was successfully screened to find coregulators of the NIN transcription factor. CONCLUSIONS: Based on the data obtained, optimal parameters were determined that allow achieving a high level of competence in yeast cells. The use of the described protocol allowed for successful screening of the library to identify coregulators of the NIN transcription factor.

Transcription factor ZmNAC19 promotes embryo development in Arabidopsis thaliana.

Overexpression of ZmNAC19, a NAC transcription factor gene from maize, improves embryo development in transgenic Arabidopsis. NAC proteins are plant-specific transcription factors that are involved in multiple aspects of plant growth, development and stress response. Although functions of many NAC transcription factors have been elucidated, little is known about their roles in seed development. In this study, we report the function of a maize NAC transcription factor ZmNAC19 in seed development. ZmNAC19 is highly expressed in embryos of developing maize seeds. ZmNAC19 localizes to nucleus and exhibits transactivation activity in yeast cells. Overexpression of ZmNAC19 in Arabidopsis significantly increases seed size and seed yield. During 3 to 7days after flowering, embryos of ZmNAC19-overexpression Arabidopsis lines developed faster compared to Col-0, while no visible differences were detected for their endosperms. Furthermore, overexpression of ZmNAC19 in Arabidopsis leads to increased transcription levels of two embryo development-related genes YUC1 and RGE1, and several elements proven to be binding sites of NAC transcription factors were observed in promoters of these two genes. Taken together, these results suggest that ZmNAC19 acts as a positive regulator in plant embryo development.

Obtaining from the cell walls of Saccharomyces cerevisiae yeast and assessing their adjuvant properties in a subunit vaccine model

Background. Polysaccharides are known to possess adjuvant properties, they are biodegradable, safe, and are of low-labor production. In this regard, the development of polysaccharide-based adjuvants is an urgent task.The aim. To develop a method for obtaining mannans from the cell walls of Saccharomyces cerevisiae yeast and to study their adjuvant properties using subunit vaccine model.Materials and methods. The preparation of mannans was obtained from the Saccharomyces cerevisiae yeast by enzymatic and alkaline hydrolysis. Its adjuvant properties were assessed in BALB/c mice immunized with the recombinant receptor-binding domain (RBD) of the SARS-CoV-2 (S) protein (Delta (B.1.617.2)). The titers of specific antibodies in the blood sera were determined by ELISA assays using the recombinant RBD (Wuhan-Hu-1 and Delta), and the recombinant (S) protein (Wuhan-Hu-1, Delta and Omicron) as antigens. The titers of virus-neutralizing antibodies were determined using virus-neutralization tests with the SARS-CoV-2 virus strains Wuhan – hCoV19/Australia/VIC01/2020 (Wuhan-Hu-1), Delta – hCoV-19/Russia/PSK-2804/2021 (Delta (B.1.617.2)), and Omicron 1 – hCoV-19/Russia/Moscow171619-031221/2021 (Omicron (B.1.1.529)).Results. The developed scheme allowed for obtaining up to 200 mg of mannans from 10 g of yeast cell debris. Double, with a two-week interval, immunization with RBD (50 μg) in combination with mannans (40 μg and 10 μg) induced the production of specific antibodies in titers from 1:2477330 to 1:188360. The titer of virus-neutralizing antibodies to the Delta – hCoV-19/Russia/PSK-2804/2021 was 1:485 (40 μg of mannans per mouse).Conclusions. We developed a scheme for obtaining a low-toxic preparation of mannans from the Saccharomyces cerevisiae yeast. The highest adjuvant activity was achieved when using mannans at the dose of 40 µg per mouse. Blood sera obtained from the immunized animals neutralized both homologous and heterologous SARS-CoV-2 strains.

Sustainable Exploitation of Wine Lees as Yeast Extract Supplement for Application in Food Industry and Its Effect on the Growth and Fermentative Ability of Lactiplantibacillus plantarum and Saccharomyces cerevisiae

Wine lees, the residue left behind after racking or bottling of wine, are predominantly composed of dead yeast cells, ethanol, phenolic compounds, and tartrates. Yeast extract (i.e., commercial yeast extract), a highly nutritious powder derived from commercially cultivated yeast biomass, is commonly used in nutrient media as a nitrogen source. In the context of by-product valorization, wine lees could potentially be used to produce a substitute for commercial yeast extract (CYE). In our study we investigated the growth and fermentative ability of two major winemaking microorganisms, Lactiplantibacillus plantarum and Saccharomyces cerevisiae, in culture media containing a wine lees yeast extract (WLYE) and a CYE. The effects of yeast extract type, concentration, and initial cell concentration (y0) on key kinetic parameters—maximum specific growth rate (μmax), lag phase duration (λ), and maximum cell concentration (ymax)—were evaluated. For L. plantarum, the results showed that using a WLYE led to similar kinetic parameters to those obtained with a CYE, with λ being unaffected by y0 in samples containing a WLYE. For S. cerevisiae, simultaneous addition of both yeast extracts led to increased μmax values (up to 0.136 h−1) compared to individually added yeast extracts, although this negatively affected λ and ymax. Current research on wine lees is mainly focused on using them as a substrate to produce valuable metabolites through fermentation, overlooking the potential industrial applications of the nutrient-rich autolysate. The findings of this study appear promising for the holistic valorization of wine lees, contributing towards the concepts of sustainability and circular economy.

Non-Invasive Characterization of Different Saccharomyces Suspensions with Ultrasound.

In fermentation processes, changes in yeast cell count and substrate concentration are indicators of yeast performance. Therefore, monitoring the composition of the biological suspension, particularly the dispersed solid phase (i.e., yeast cells) and the continuous liquid phase (i.e., medium), is a prerequisite to ensure favorable process conditions. However, the available monitoring methods are often invasive or restricted by detection limits, sampling requirements, or susceptibility to masking effects from interfering signals. In contrast, ultrasound measurements are non-invasive and provide real-time data. In this study, the suitability to characterize the dispersed and the liquid phase of yeast suspensions with ultrasound was investigated. The ultrasound signals collected from three commercially available Saccharomyces yeast were evaluated and compared. For all three yeasts, the attenuation coefficient and speed of sound increased linearly with increasing yeast concentrations (0.0-1.0 wt%) and cell counts (R2 > 0.95). Further characterization of the dispersed phase revealed that cell diameter and volume density influence the attenuation of the ultrasound signal, whereas changes in the speed of sound were partially attributed to compositional variations in the liquid phase. This demonstrates the ability of ultrasound to monitor industrial fermentations and the feasibility of developing targeted control strategies.

Effects of flavonoids on yeast ABC transporters activity

Flavonoids are known to be effective biomodulators of various processes in eukaryotic cells. As these compounds are present in wine and beer raw materials, they can influence the qualitative characteristics of the ethanol content in wine-making and brewing products, including directly through the mechanisms of regulation of gene expression and the activity of ATP-binding cassette (ABC) proteins. The main function of ABC transporters in yeast cells is to transport various substrates, including ethanol. This process ensures the survival of yeast cells under conditions of ethanol stress. It has been found that flavonoids, as well as their Schiff base derivatives, are effective stimulators and inhibitors of mRNA expression and activity of ABC proteins both in logarithmic and stationary phases of growth, which has a direct impact on bioethanol production by yeast.

Action enhancement of antimicrobial peptides by their combination with enzymes hydrolyzing fungal quorum molecules

Recently, the lactonase activity of several enzymes (lactonase AiiA, organophosphate hydrolase (His6-OPH) and New Delhi metallo-β-lactamase (NDM-1)) was revealed in the hydrolysis of lactone-containing fungal Quorum Sensing molecules (FQSM). This study was aimed at the investigation of possible use of these enzymes as components of antifungal combinations with antimicrobial peptides (AMPs) to increase their action efficiency against various fungi. For this, the interaction of various AMPs with AiiA, NDM-1 or His6-OPH, as well as the effect of AMPs on the catalytic characteristics of these enzymes in the hydrolysis of FQSM in enzyme/AMP combinations, were studied using in silico computer modeling methods. Enzymes combinations with 3 AMPs Bacitracin, Colistin and Polymyxin B were selected as the most rational in terms of maintaining the effectiveness of AMP and the catalytic activity of enzymes. The antifungal action of the selected combinations against cells of mycelial fungi and yeast was studied in vitro. It was found that combinations of the enzymes AiiA, His6-OPH and NDM-1 with Bacitracin, Colistin and Polymyxin B provide a significant increase in the action efficiency (up to 5000 times) of both AMPs and enzymes against fungi. The most effective variants were obtained for Polymyxin B in multicomponent combinations with enzymes.

Microbial Biocapsules as Generally Recognized-As-Safe Fungal-Based Immobilized Cell Technology for Precision Sequential Fermentations of Grape Must

This work focuses on the production of a white wine with a specific organoleptic profile by means of sequential fermentation using immobilized yeast in a system known as “microbial biocapsules”. Three fermentation conditions were created: sequential fermentation with immobilized yeast (SqFMB) employing a matrix composed by Aspergillus oryzae (pellet-forming fungus recognized as GRAS), sequential fermentations with non-immobilized yeast cells (SqF), and a control of spontaneous fermentation (SpF). To carry out these fermentations, Pedro Ximénez grape must was used and two non-Saccharomyces yeast strains, Debaryomyces hansenii LR1 and Metschnikowia pulcherimma Primaflora, and the Saccharomyces cerevisiae X5 strain were used. The wines produced were subjected to microbiological and chemical analyses in which metabolites that positively influence the wine profile, such as 1,1-diethoxyethane and decanal, are only produced in the SqFMB condition, and others, like nonanal, were detected in higher concentrations than in SqF and SpF. Microbiological analyses show that less non-Saccharomyces yeasts were isolated in the SqFMB condition than in SqF, which indicates an efficiency in the inoculation and removal method proposed. These results conclude that microbial biocapsules seem to be a good yeast carrier for wine elaboration; however, modulation of some variables like yeast concentration inocula, the employment of preadaptation methods or the use of yeast species with higher fermentative power need to be tested to improve the novel methodology.