Interactions In Yeast Research Articles

Identification and Biotransformation of Volatile Markers During the Early Stage of Zygosaccharomyces rouxii and Zygosaccharomyces mellis Contamination in Acacia Honey.

To address the volatile markers and their biotransformation during the early stage of Zygosaccharomyces spp. contamination in acacia honey, headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and chemometric analyses were used to explore the variation of volatile compounds. A total of 36 and 35 volatile compounds were identified before and after contamination of Zygosaccharomyces rouxii and Zygosaccharomyces mellis, respectively. Methyl butyrate and 2-methyl-3-pentanone could be used as volatile markers of Z. rouxii and Z. mellis-contaminated honey, which were both specific products of the yeast's own fermentation. 2,5-Dimethylbenzaldehyde was identified as a volatile marker of Z. rouxii and Z. mellis-contaminated acacia honey, and it was a specific product resulting from the interaction of yeast and acacia honey. In addition, β-damascenone could be determined as a potential volatile marker after Z. rouxii-contaminated acacia honey. Methyl 2-methylbutyrate was used as a potential volatile marker in the high-concentration groups of Z. rouxii and Z. mellis. The content ranges of methyl butyrate, 2-methyl-3-pentanone, and 2,5-dimethylbenzaldehyde in four samples were 6.62-14.59, 3.15-5.42, and 52.52-215.19 μg/mL, respectively. The variation of volatile markers during the early stage of osmotolerant yeast contamination provided a theoretical basis for the use of HS-SPME-GC-MS for the rapid detection of acacia honey deterioration while reducing economic losses.

Exploring Microbial Dynamics: The Interaction between Yeasts and Acetic Acid Bacteria in Port Wine Vinegar and Its Implications on Chemical Composition and Sensory Acceptance

Port wine vinegar, a product of the esteemed Port wine, is renowned for its intricate blend of flavors and aromas, a result of complex microbial interactions. This study delves into the fascinating world of yeast and acetic acid bacteria (AAB) interactions during fermentation, which significantly influence the vinegar’s chemical composition and sensory properties. We specifically investigate the role of yeasts in fermenting sugars into ethanol, a process that AAB then converts into acetic acid. The impact of these interactions on the production of secondary metabolites, such as gluconic acid, ketones, aldehydes, and esters, which contribute to the vinegar’s unique sensory profile, is thoroughly examined. Advanced analytical techniques, including GC-MS and e-nose technology, alongside sensory evaluation, are employed to assess these effects. The research underscores the significance of ethanol tolerance in AAB and other production challenges in determining vinegar quality and underscores the importance of optimizing fermentation conditions and sustainable practices. The findings of this study underscore the importance of strain interactions and production techniques, which can significantly enhance the quality and market appeal of Port wine vinegar, providing valuable insights for the industry. This review also identifies exciting and critical areas for future research, inspiring further exploration and proposing strategies for advancing production and application in culinary, health, and industrial contexts.

Physical cell-cell contact elicits specific transcriptomic responses in wine yeast species.

Fermenting grape juice provides a habitat for a well-mapped and evolutionarily relevant microbial ecosystem consisting of many natural or inoculated strains of yeasts and bacteria. The molecular nature of many of the ecological interactions within this ecosystem remains poorly understood, with the partial exception of interactions of a metabolic nature such as competition for nutrients and production of toxic metabolites/peptides. Data suggest that physical contact between species plays a significant role in the phenotypic outcome of interspecies interactions. However, the molecular nature of the mechanisms regulating these phenotypes remains unknown. Here, we present a transcriptomic analysis of physical versus metabolic contact between two wine relevant yeast species, Saccharomyces cerevisiae and Lachancea thermotolerans. The data show that these species respond to the physical presence of the other species. In S. cerevisiae, physical contact results in the upregulation of genes involved in maintaining cell wall integrity, cell wall structural components, and genes involved in the production of H2S. In L. thermotolerans, HSP stress response genes were the most significantly upregulated gene family. Both yeasts downregulated genes belonging to the FLO family, some of which play prominent roles in cellular adhesion. qPCR analysis indicates that the expression of some of these genes is regulated in a species-specific manner, suggesting that yeasts adjust gene expression to specific biotic challenges or interspecies interactions. These findings provide fundamental insights into yeast interactions and evolutionary adaptations of these species to the wine ecosystem.IMPORTANCEWithin the wine ecosystem, yeasts are the most relevant contributors to alcoholic fermentation and wine organoleptic characteristics. While some studies have described yeast-yeast interactions during alcoholic fermentation, such interactions remain ill-defined, and little is understood regarding the molecular mechanisms behind many of the phenotypes observed when two or more species are co-cultured. In particular, no study has investigated transcriptional regulation in response to physical interspecies cell-cell contact, as opposed to the generally better understood/characterized metabolic interactions. These data are of direct relevance to our understanding of microbial ecological interactions in general while also creating opportunities to improve ecosystem-based biotechnological applications such as wine fermentation. Furthermore, the presence of competitor species has rarely been considered an evolutionary biotic selection pressure. In this context, the data reveal novel gene functions. This, and further such analysis, is likely to significantly enlarge the genome annotation space.

Modeling and Optimizing Biocontrol in Wines: pH as a Modulator of Yeast Amensalism Interaction

The control of spoilage yeasts in wines is crucial to avoid organoleptic deviations in wine production. Traditionally, sulfur dioxide (SO2) was used to control them; nevertheless, SO2 influence on human health and its use is criticized. Biocontrol emerges as an alternative in wine pre-fermentation, but there is limited development in its applicability. Managing kinetics is relevant in the microbial interaction process. pH was identified as a factor affecting the interaction kinetics of Wickerhamomyces anomalus killer biocontrol on Zygosaccharomyces rouxii. Mathematical modeling allows insight into offline parameters and the influence of physicochemical factors in the environment. Incorporating submodels that explain manipulable factors (pH), the process can be optimized to achieve the best-desired outcomes. The aim of this study was to model and optimize, using a constant and a variable pH profile, the interaction of killer biocontrol W. anomalus vs. Z. rouxii to reduce the spoilage population in pre-fermentation. The evaluated biocontrol was W. anomalus against the spoilage yeast Z. rouxii in wines. The kinetic interactions of yeasts were studied at different pH levels maintained constant over time. The improved Ramón-Portugal model was adopted using the AMIGO2 toolbox for Matlab. A static optimization of a constant pH profile was performed using the Monte Carlo method, and a dynamic optimization was carried out using a method based on Fourier series and orthogonal polynomials. The model fit with an adjusted R2 of 0.76. Parametric analyses were consistent with the model behavior. Variable vs. constant optimization achieved a lower initial spoilage population peak (99% less) and reached a lower final population (99% less) in a reduced time (100 vs. 140 h). These findings reveal that control with a variable profile would allow an early sequential inoculation of S. cerevisiae. The models explained parameters that are difficult to quantify, such as general inhibitor concentration and toxin concentration. Also, the models indicate higher biocontrol efficiency parameters, such as toxin emission or sensitivity to it, and lower fitness of the contaminant, at pH levels above 3.7 during biocontrol. From a technological standpoint, the study highlights the importance of handling variable profiles in the controller associated with the pH management actuators in the process without incurring additional costs.

Unlocking fungal quorum sensing: Oxylipins and yeast interactions enhance secondary metabolism in monascus

Exploring the symbiotic potential between fungal and yeast species, this study investigates the co-cultivation dynamics of Monascus, a prolific producer of pharmacologically relevant secondary metabolites, and Wickerhamomyce anomalous. The collaborative interaction between these microorganisms catalyzed a substantial elevation in the biosynthesis of secondary metabolites, prominently Monacolin K and natural pigments. Central to our discoveries was the identification and enhanced production of oxylipins (13S-hydroxyoctadecadienoic acid，13S-HODE), putative quorum-sensing molecules, within the co-culture environment. Augmentation with exogenous oxylipins not only boosted Monacolin K production by over half but also mirrored morphological adaptations in Monascus, affecting both spores and mycelial structures. This augmentation was paralleled by a significant upregulation in the transcriptional activity of genes integral to the Monacolin K biosynthetic pathway, as well as genes implicated in pigment and spore formation. Through elucidating the interconnected roles of quorum sensing, G-protein-coupled receptors, and the G-protein-mediate signaling pathway, this study provides a comprehensive view of the molecular underpinnings facilitating these metabolic enhancements. Collectively, our findings illuminate the profound influence of Wickerhamomyces anomalous co-culture on Monascus purpureus, advocating for oxylipins as a pivotal quorum-sensing mechanism driving the observed symbiotic benefits.

Strain specific Starmerella bacillaris and Saccharomyces cerevisiae interactions in mixed fermentations.

Yeast interactions have a key role in the definition of the chemical profile of the wines. For this reason, winemakers are increasingly interested in mixed fermentations, employing Saccharomyces cerevisiae and non-Saccharomyces strains. However, the outcome of mixed fermentations is often contradictory because there is a great variability among strains within species. Previously, it was demonstrated that the loss of culturability of Starmerella bacillaris in mixed fermentations with S. cerevisiae was due to the physical contact between cells. Therefore, to further explore previous observations, the interaction mechanisms among different strains of Starm. bacillaris and S. cerevisiae during mixed fermentations were investigated. Fermentations were conducted under conditions that allow physical contact between cells (flasks) but also using a double-compartment fermentation system in which cells of both species were kept separate. The role of competition for nutrients and antimicrobial compounds production on yeast-yeast interaction mechanisms was also investigated. Three Starm. bacillaris and three S. cerevisiae strains were used to investigate if interaction mechanisms are modulated in a strain-specific way. Both species populations were affected by physical contact, particularly Starm. bacillaris that lost its culturability during fermentation. In addition, loss of culturability of Starm. bacillaris strains was observed earlier in flasks than in the double-compartment system. The phenomena observed occurred in a strain couple-dependent way. Starm. bacillaris disappearance seemed to be independent of nutrient depletion or the presence of inhibitory compounds (which were not measured in this study). Overall, the results of the present study reveal that cell-to-cell contact plays a role in the early death of non-Saccharomyces but the extent to which it is observed depends greatly on the Starm. bacillaris/S. cerevisiae strains tested.

Transcriptional Analysis of Mixed-Culture Fermentation of Lachancea thermotolerans and Saccharomyces cerevisiae for Natural Fruity Sour Beer

Increasingly high interest in yeast–yeast interactions in mixed-culture fermentation is seen along with beer consumers’ demands driving both market growth and requests for biotechnological solutions that can provide better sensory characteristics. In this study, Lachancea thermotolerans and Saccharomyces cerevisiae with a cell population ratio of 10:1 were inoculated for sour beer fermentation while the process conditions within the brewing industry remained unchanged. With L. thermotolerans producing lactic acid (1.5–1.8 g/L) and bringing down the pH to 3.3–3.4 whilst adding no foreign flavors herein, this study revealed a new natural, fruity sour beer with a soft, sour taste. In this study, the double-yeast mixed-culture fermentation produced more flavor substances than a single-culture process, and plenty of isobutyl acetate and isoamyl acetate enhanced the fruit aroma and balanced the sour beer with a refreshing taste. While playing a positive role in improving the beer’s quality, the double-yeast mixed-culture fermentation developed in this study helps to offer an alternative mass production solution for producing sour beer with the processes better controlled and the fermentation time reduced. The stress responses of the L. thermotolerans during the fermentation were revealed by integrating RNA sequencing (RNA-Seq) and metabolite data. Given that the metabolic flux distribution of the S. cerevisiae during the fermentation differed from that of the non-Saccharomyces yeasts, transcriptional analysis of non-Saccharomyces yeast and S. cerevisiae could be suitable in helping to develop strategies to modulate the transcriptional responses of specific genes that are associated with the aroma compounds released by S. cerevisiae and non-Saccharomyces yeasts. In the case of some non-Saccharomyces yeast species/strains, the diversion of alcoholic fermentation and the formation of a great number of secondary compounds may, in part, account for the low ethanol yield.

Protein-Protein Interactions of Seryl-tRNA Synthetases with Emphasis on Human Counterparts and Their Connection to Health and Disease.

Seryl-tRNA synthetases (SerRSs), members of the aminoacyl-tRNA synthetase family, interact with diverse proteins, enabling SerRSs to enhance their role in the translation of the genetic message or to perform alternative functions in cellular processes beyond translation. Atypical archaeal SerRS interacts with arginyl-tRNA synthetase and proteins of the ribosomal P-stalk to optimize translation through tRNA channeling. The complex between yeast SerRS and peroxin Pex21p provides a connection between translation and peroxisome function. The partnership between Arabidopsis SerRS and BEN1 indicates a link between translation and brassinosteroid metabolism and may be relevant in plant stress response mechanisms. In Drosophila, the unusual heterodimeric mitochondrial SerRS coordinates mitochondrial translation and replication via interaction with LON protease. Evolutionarily conserved interactions of yeast and human SerRSs with m3C32 tRNA methyltransferases indicate coordination between tRNA modification and aminoacylation in the cytosol and mitochondria. Human cytosolic SerRS is a cellular hub protein connecting translation to vascular development, angiogenesis, lipogenesis, and telomere maintenance. When translocated to the nucleus, SerRS acts as a master negative regulator of VEGFA gene expression. SerRS alone or in complex with YY1 and SIRT2 competes with activating transcription factors NFκB1 and c-Myc, resulting in balanced VEGFA expression important for proper vascular development and angiogenesis. In hypoxia, SerRS phosphorylation diminishes its binding to the VEGFA promoter, while the lack of nutrients triggers SerRS glycosylation, reducing its nuclear localization. Additionally, SerRS binds telomeric DNA and cooperates with the shelterin protein POT1 to regulate telomere length and cellular senescence. As an antitumor and antiangiogenic factor, human cytosolic SerRS appears to be a promising drug target and therapeutic agent for treating cancer, cardiovascular diseases, and possibly obesity and aging.

Ectopic BH3-Only Protein Bim Associates with Hsp70 to Regulate Yeast Mitophagy

Mitophagy, a form of selective autophagy, plays an essential role to maintain a population of healthy and functional mitochondria for normal cellular metabolism. Acting mainly as one of the B-cell lymphoma 2 (Bcl-2) family pro-apoptotic members, Bim (also known as BCL2L11) was identified to be a co-chaperone of Hsp70 to promote mitophagy in mammalian cells. Herein, with the help of a specific Hsp70/Bim disruptor and Om45-GFP processing assay, we illustrated that ectopic BimEL is able to promote mitophagy through Hsp70/Bim interaction in yeast, where Bax/Bak is absent. The Hsp70/Bim-mediated mitophagy is conserved in eukaryotes, from yeast to humans.

Enhanced probiotic potential of Lactobacillus kefiranofaciens OSU-BDGOA1 through co-culture with Kluyveromyces marxianus bdgo-ym6.

Due to the increasing consumer demand for the development and improvement of functional foods containing probiotics, new probiotic candidates need to be explored as well as novel means to enhance their beneficial effects. Lactobacillus kefiranofaciens OSU-BDGOA1 is a strain isolated from kefir grains that has demonstrated probiotic traits. This species is the main inhabitant of kefir grains and is responsible for the production of an exopolysaccharide (EPS) whit vast technological applications and potential bioactivities. Research has shown that interkingdom interactions of yeast and lactic acid bacteria can enhance metabolic activities and promote resistance to environmental stressors. Comparative genomic analyses were performed to distinguish OSU-BDGOA1 from other strains of the same species, and the genome was mined to provide molecular evidence for relevant probiotic properties. We further assessed the cumulative effect on the probiotic properties of OSU-BDGOA1 and Kluyveromyces marxianus bdgo-ym6 yeast co-culture compared to monocultures. Survival during simulated digestion assessed by the INFOGEST digestion model showed higher survival of OSU-BDGOA1 and bdgo-ym6 in co-culture. The adhesion to intestinal cells assessed with the Caco-2 intestinal cell model revealed enhanced adhesion of OSU-BDGOA1 in co-culture. The observed increase in survival during digestion could be associated with the increased production of EPS during the late exponential and early stationary phases of co-culture that, by enhancing co-aggregation between the yeast and the bacterium, protects the microorganisms from severe gastrointestinal conditions as observed by SEM images. Immune modulation and barrier function for recovery and prevention of flagellin-mediated inflammation by Salmonella Typhimurium heat-killed cells (HKSC) in Caco-2 cells were also measured. OSU-BDGOA1 in mono- and co-culture regulated inflammation through downregulation of pro-inflammatory cytokine expression and increased membrane barrier integrity assessed by TEER, FD4 permeability, and expression of tight junctions. The results of the study warrant further research into the application of co-cultures of yeast and LAB in functional probiotic products and the potential to increase EPS production by co-culture strategies.

A Novel Strategy Based on Zn(II) Porphyrins and Silver Nanoparticles to Photoinactivate Candida albicans.

Photodynamic inactivation (PDI) is an attractive alternative to treat Candida albicans infections, especially considering the spread of resistant strains. The combination of the photophysical advantages of Zn(II) porphyrins (ZnPs) and the plasmonic effect of silver nanoparticles (AgNPs) has the potential to further improve PDI. Here, we propose the novel association of polyvinylpyrrolidone (PVP) coated AgNPs with the cationic ZnPs Zn(II) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin or Zn(II) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin to photoinactivate C. albicans. AgNPs stabilized with PVP were chosen to allow for (i) overlap between the NP extinction and absorption spectra of ZnPs and (ii) favor AgNPs-ZnPs interaction; prerequisites for exploring the plasmonic effect. Optical and zeta potential (ζ) characterizations were performed, and reactive oxygen species (ROS) generation was also evaluated. Yeasts were incubated with individual ZnPs or their respective AgNPs-ZnPs systems, at various ZnP concentrations and two proportions of AgNPs, then irradiated with a blue LED. Interactions between yeasts and the systems (ZnP alone or AgNPs-ZnPs) were evaluated by fluorescence microscopy. Subtle spectroscopic changes were observed for ZnPs after association with AgNPs, and the ζ analyses confirmed AgNPs-ZnPs interaction. PDI using ZnP-hexyl (0.8 µM) and ZnP-ethyl (5.0 µM) promoted a 3 and 2 log10 reduction of yeasts, respectively. On the other hand, AgNPs-ZnP-hexyl (0.2 µM) and AgNPs-ZnP-ethyl (0.6 µM) systems led to complete fungal eradication under the same PDI parameters and lower porphyrin concentrations. Increased ROS levels and enhanced interaction of yeasts with AgNPs-ZnPs were observed, when compared with ZnPs alone. We applied a facile synthesis of AgNPs which boosted ZnP efficiency. We hypothesize that the plasmonic effect combined with the greater interaction between cells and AgNPs-ZnPs systems resulted in an efficient and improved fungal inactivation. This study provides insight into the application of AgNPs in PDI and helps diversify our antifungal arsenal, encouraging further developments toward inactivation of resistant Candida spp.

Yeast–amoeba interaction influences murine cryptococcosis

The virulence of Cryptococcus spp. is modulated in the natural environment through interaction with abiotic and biotic factors, and this can occasionally have implications for the progression of cryptococcosis in mammals. Hence, we evaluated whether the prior interaction of highly virulent Cryptococcus gattii strain R265 with Acanthamoeba castellanii influenced the progression of cryptococcosis. The influence of the capsule on endocytosis was evaluated using amoeba and yeast morphometrics. Mice were intratracheally infected with yeast re-isolated from the amoeba (Interaction), yeast without prior contact with the amoeba (Non-Interaction), or sterile phosphate-buffered saline (SHAM). Morbidity signs and symptoms were monitored during the survival curve, while cytokine and fungal burden measurements and histopathological analysis were performed on the 10th day post infection. Morbidity and mortality parameters in experimental cryptococcosis were influenced by the prior interaction of yeast with amoeba, which led to phenotypic changes in the cryptococcal cells, polysaccharide secretion, and their tolerance to oxidative stress. Our results suggest that a prior yeast–amoeba interaction modulates yeast virulence, which is associated with a greater tolerance to oxidative stress related to the exo-polysaccharide content and influences the progression of cryptococcal infection.

Pesticide and Yeast Interaction in Alcoholic Fermentation: A Mini-Review

The current investigation briefly reviews previous studies about the fate of pesticides used in wine grape production during the alcoholic fermentation process, and how these could affect the correct functioning of yeast. The present review discusses the fact that yeasts could be used as a biological tool for pesticide dissipation, diminishing the concentration present in the grapes during the production process. The previous have never been directly boarded by other authors. The first part explores the influences of pesticides on yeasts and elucidates their effect on the fermentation process; also, some examples are analyzed of molecular studies involving the effect of pesticides on yeast. The second part discusses the effect of yeast on pesticide residues and their capacity to reduce its concentration during the alcoholic fermentation process, which varies among the different pesticides. In addition, this review discusses the mechanism by which yeast cells adsorb and/or degrade pesticides. In the last part, some examples of using yeasts as a possible remediation tool in wine and how the industry could use this to ensure consumers that a product is without pesticide residues are also discussed. This review shows that there is a natural capacity for the reduction of pesticide residue concentration by yeasts, and the effects of pesticides on yeast development is a variable phenomenon. This information guides advancement in pesticide removal from wine.

Expanding the diversity of Chardonnay aroma through the metabolic interactions of Saccharomyces cerevisiae cocultures.

Yeast co-inoculations in winemaking are often studied in the framework of modulating the aromatic profiles of wines. Our study aimed to investigate the impact of three cocultures and corresponding pure cultures of Saccharomyces cerevisiae on the chemical composition and the sensory profile of Chardonnay wine. Coculture makes it possible to obtain completely new aromatic expressions that do not exist in the original pure cultures attributed to yeast interactions. Esters, fatty acids and phenol families were identified as affected. The sensory profiles and metabolome of the cocultures, corresponding pure cultures and associated wine blends from both pure cultures were found to be different. The coculture did not turn out to be the addition of the two pure culture wines, indicating the impact of interaction. High resolution mass spectrometry revealed thousands of cocultures biomarkers. The metabolic pathways involved in these wine composition changes were highlighted, most of them belonging to nitrogen metabolism.

Impacts of vitamin premix and/or yeast ingredient inclusion in a canned cat food on thiamin retention during 6 months of storage.

Low thiamin levels in thermally processed canned cat foods are concerning for the pet food industry. However, there is little information on storage stability of thiamin in this food format or if inclusion of select ingredients, such as dried yeasts, has an effect. Therefore, the objective was to evaluate the storage stability of thiamin when a vitamin premix and/or yeasts ingredients were included in a canned cat food. The factorial treatment arrangement consisted of 2 levels of vitamin premix (with or without) and 4 inclusions of yeast (NY = none, LBV = Lalmin B Complex Vitamins, BY = product #1064B, or EA = BGYADVANTAGE). Diets were stored for 6 months and analyzed every month for thiamin. Data were analyzed as a mixed model (SAS v. 9.4; SAS Institute, Cary, NC) with fixed effects (vitamin premix, yeast, time, and their two-way and three-way interactions) and random effects (production day and the interaction of production day, vitamin premix, and yeast). Significance was set at P < 0.05 and Fisher's LSD was used to separate means. Diets including the vitamin premix [average 55.1 mg/kg dry matter basis (DMB)] contained more (P < 0.05) thiamin than diets that did not (average 7.5 mg/kg DMB). Inclusion of LBV (average 40.3 mg/kg DMB) resulted in the highest (P < 0.05) levels of thiamin, followed by BY (P < 0.05; average 26.9 mg/kg DMB). Diets with NY and EA contained the lowest (P < 0.05) levels of thiamin and were not different from each other (P > 0.05; average 19.3 mg/kg DMB). The diet containing vitamin premix without yeast lost (P < 0.05) 17.8% thiamin while diets containing a yeast ingredient maintained thiamin levels better during storage. This suggested that thiamin from yeast ingredients was more resistant to degradation during storage and should be considered when designing new canned cat foods.

Evaluation of the electrochemical response of Saccharomyces cerevisiae using screen-printed carbon electrodes (SPCE) modified with oxidized multi-walled carbon nanotubes dispersed in water – Nafion®

The evaluation of the electrochemical determination of Saccharomyces cerevisiae was carried out using a screen-printed carbon electrode (SPCE) modified with Nafion-dispersed oxidized multi-walled carbon nanotubes (OMWCNT). The morphology was studied using scanning electron microscopy (SEM), showing a complete modification of the surface with the nanotubes and yeast interaction with them instead of the graphite surface. The redox couple Fe(CN)64−/Fe(CN)63− was used to determine the electroactive area, the heterogeneous transfer constant, and the Nafion® effect. Results showed increases in electroactive area and heterogeneous transfer constant of 146% and 20.4%, respectively, due to the presence of nanotubes. Studies of the Nafion® effect showed that the polymeric membrane affects the electroactive area but not the heterogeneous transfer constant. Studies of the scan rate effect show that yeast oxidation is an irreversible mixed control process. As the concentration and scan rate increased, the anodic potential shifted toward more anodic values. The relationship between yeast concentration and the anodic current density (current/electroactive area) of yeast showed a linear range between 0.61 and 7.69 g L−1, the limit of detection (LOD) and the limit of quantification (LOQ) were 0.17 g L−1, and 0.61 g L−1, respectively, and the sensibility obtained was 0.03 μA L g−1 mm−2. These results show that with the screen-printed carbon electrodes it is possible to improve the electrochemical determination of this microorganism, enhancing the analytical parameters and quantification, allowing greater portability and decreasing measurement times and associated waste.

Cultivar-Dependent Effects of Non-Saccharomyces Yeast Starter on the Oenological Properties of Wines Produced from Two Autochthonous Grape Cultivars in Southern Italy.

Global warming poses a threat to winemaking worldwide, especially in dry-warm regions such as Southern Italy. Must fermentation with non-Saccharomyces yeast starter is a possible approach to limit the negative effects of climate change, leading to desirable effects such as an increase in total acidity and/or aroma improvement. The aim of this study was to evaluate the effects of the use of a non-Saccharomyces starter (Lachancea thermotolerans) on the chemical and sensory properties of wines obtained by the the fermentation of two autochthonous Apulian grape cultivars, namely Bombino nero and Minutolo, as compared to the traditional Saccharomyces cerevisiae-driven fermentation. Bombino and Minutolo wines fermented with either Lachancea thermotolerans or Saccharomyces cerevisiae were characterized for their oenological parameters, volatile profiles, and sensory properties. Both chemical and sensory properties were affected by the yeast starter. Inoculation of L. thermotolerans increased sensory complexity, with different floral and sweet-like attributes for both cultivars. Bombino nero, a neutral cultivar, showed a clear effect on wine composition, with both an increase in lactic acid and a change in the volatile profile. On the contrary, the impact of L. thermotolerans was partially masked in Minutolo due to the strong primary aroma background of this highly terpenic cultivar. In this work, we evidenced a notable cultivar × yeast interaction, showing how generalizations of the effects of non-Saccharomyces yeasts on vinification are difficult to achieve, as they show a cultivar-specific outcome.

Limited Proteolysis-Mass Spectrometry to Identify Metabolite-Protein Interactions.

Metabolite-protein interactions regulate diverse cellular processes, prompting the development of methods to investigate the metabolite-protein interactome at a global scale. One such method is our previously developed structural proteomics approach, limited proteolysis-mass spectrometry (LiP-MS), which detects proteome-wide metabolite-protein and drug-protein interactions in native bacterial, yeast, and mammalian systems, and allows identification of binding sites without chemical modification. Here we describe a detailed experimental and analytical workflow for conducting a LiP-MS experiment to detect small molecule-protein interactions, either in a single-dose (LiP-SMap) or a multiple-dose (LiP-Quant) format. LiP-Quant analysis combines the peptide-level resolution of LiP-MS with a machine learning-based framework to prioritize true protein targets of a small molecule of interest. We provide an updated R script for LiP-Quant analysis via a GitHub repository accessible at https://github.com/RolandBruderer/MiMB-LiP-Quant .

Yeasts as a Potential Biological Agent in Plant Disease Protection and Yield Improvement—A Short Review

The role of biocontrol products is expected to increase worldwide consumer demand and facilitate the implementation of sustainable agricultural policies. New biocontrol agents must allow for an effective crop-protection strategy in sustainable agriculture. Yeasts are microorganisms living in various niches of the environment that can be antagonists of many plant pathogens. Yeasts rapidly colonize plant surfaces, use nutrients from many sources, survive in a relatively wide temperature range, produce no harmful metabolites and have no deleterious effects on the final food products. Hence, they can be a good biocontrol agent. In this paper, the biological characteristics and potential of yeast are summarized. Additionally, the mechanisms of yeasts as plant-protection agents are presented. This includes the production of volatile organic compounds, production of killer toxins, competition for space and nutrient compounds, production of lytic enzymes, induction of plant immunity and mycoparasitism. The mechanisms of yeast interaction with plant hosts are also described, and examples of yeasts used for pre- and postharvest biocontrol are provided. Commercially available yeast-based products are listed and challenges for yeast-based products are described.

Lack of alignment across yeast-dependent life-history traits may limit Drosophila melanogaster dietary specialization.

Heterogeneity in food resources is a major driver of local adaptation and speciation. Dietary specialization typically involves multiple life‐history traits and may thus be limited by the extent to which these traits adapt in concert. Here, we use Drosophila melanogaster, representing an intermediate state in the generalist‐specialist continuum, to explore the scope for dietary specialization. D. melanogaster has a close association with yeast, an essential but heterogeneous food resource. We quantify how different D. melanogaster strains from around the globe respond to different yeast species, across multiple yeast‐dependent life‐history traits including feeding, mating, egg‐laying, egg development and survival. We find that D. melanogaster strains respond to different yeast species in different ways, indicating distinct fly strain–yeast interactions. However, we detect no evidence for trade‐offs: fly performance tends to be positively rather than negatively correlated across yeast species. We also find that the responses to different yeast species are not aligned across traits: different life‐history traits are maximized on different yeast species. Finally, we confirm that D. melanogaster is a resource generalist: it can grow, reproduce and survive on all the yeast species we tested. Together, these findings provide a possible explanation for the limited extent of dietary specialization in D. melanogaster.