Yeast Strains Research Articles

Performance and yield estimation of sugarcane varieties for pot still cachaça production

Cachaça is an alcoholic beverage obtained through the distillation of fermented sugarcane juice. It is the sugarcane distillate most consumed in Brazil. Despite the traditional nature and economic importance of cachaça, the production chain in Brazil is not technologically homogeneous; low-yielding varieties of sugarcane with susceptibility to various diseases are common. The pot still cachaças undergo delicate distillation processes in copper pot stills using wild yeast strains for fermentation, and the most exceptional and expensive cachaças can be found on the market in Brazil. The objective of this study was to assess modern sugarcane varieties for the production of pot still cachaça and to propose a new methodology to obtain the expected yield in liters of cachaça per hectare. A randomized block experimental design was used in a 4 (sugarcane varieties) × 3 (harvest times) factorial arrangement, with five replications. At the end of three crop seasons after harvest, the yield components, soluble solids content, and expected cachaça yield were evaluated. The highest levels of soluble solids (ºBrix) were for CTC4 and RB966928. Based on data from three crop seasons, the CTC9002 variety showed the highest stalk yield per hectare (SYH). The estimated yield methodology allowed for comprehensive assessment of the main sugarcane production characteristics, providing reliability and practicality in estimating cachaça yield. Based on analysis of yield components and mean cachaça yield (liters/ha) over three crop seasons, CTC9002 is recommended for inclusion in the panel of varieties for cachaça production.

Functional characterization and structural basis of an efficient ochratoxin A-degrading amidohydrolase

Ochratoxin A (OTA) contamination in various agro-products poses a serious threat to the global food safety and human health, leading to enormous economic losses. Enzyme-mediated OTA degradation is an appealing strategy, and the search for more efficient enzymes is a prerequisite for achieving this goal. Here, a novel amidohydrolase, termed PwADH, was demonstrated to exhibit 7.3-fold higher activity than that of the most efficient OTA-degrading ADH3 previously reported. Cryo-electron microscopy structure analysis indicated that additional hydrogen-bond interactions among OTA and the adjacent residue H163, the more compact substrate-binding pocket, and the wider entry to the substrate-access cavity might account for the more efficient OTA-degrading activity of PwADH compared with that of ADH3. We conducted a structure-guided rational design of PwADH and obtained an upgraded variant, G88D, whose OTA-degrading activity was elevated by 1.2-fold. In addition, PwADH and the upgraded G88D were successfully expressed in the industrial yeast Pichia pastoris, and their catalytic activities were compared to those of their counterparts produced in E. coli, revealing the feasibility of producing PwADH and its variants in industrial yeast strains. These results illustrate the structural basis of a novel, efficient OTA-degrading amidohydrolase and will be beneficial for the development of high-efficiency OTA-degrading approaches.

Enantiocomplementary Bioreduction of 1-(Arylsulfanyl)propan-2-ones.

This study explored the enantiocomplementary bioreduction of substituted 1-(arylsulfanyl)propan-2-ones in batch mode using four wild-type yeast strains and two different recombinant alcohol dehydrogenases from Lactobacillus kefir and Rhodococcus aetherivorans. The selected yeast strains and recombinant alcohol dehydrogenases as whole-cell biocatalysts resulted in the corresponding 1-(arylsulfanyl)propan-2-ols with moderate to excellent conversions (60-99%) and high selectivities (ee > 95%). The best bioreductions-in terms of conversion (>90%) and enantiomeric excess (>99% ee)-at preparative scale resulted in the expected chiral alcohols with similar conversion and selectivity to the screening reactions.

De novo biosynthesis of anthocyanins in Saccharomyces cerevisiae using metabolic pathway synthases from blueberry

BackgroundAnthocyanins are water-soluble flavonoids in plants, which give plants bright colors and are widely used as food coloring agents, nutrients, and cosmetic additives. There are several limitations for traditional techniques of collecting anthocyanins from plant tissues, including species, origin, season, and technology. The benefits of using engineering microbial production of natural products include ease of use, controllability, and high efficiency.ResultsIn this study, ten genes encoding enzymes involved in the anthocyanin biosynthetic pathway were successfully cloned from anthocyanin-rich plant materials blueberry fruit and purple round eggplant rind. The Yeast Fab Assembly technology was utilized to construct the transcriptional units of these genes under different promoters. The transcriptional units of PAL and C4H, 4CL and CHS were fused and inserted into Chr. XVI and IV of yeast strain JDY52 respectively using homologous recombination to gain Strain A. The fragments containing the transcriptional units of CHI and F3H, F3’H and DFR were inserted into Chr. III and XVI to gain Strain B1. Strain B2 has the transcriptional units of ANS and 3GT in Chr. IV. Several anthocyanidins, including cyanidin, peonidin, pelargonidin, petunidin, and malvidin, were detected by LC-MS/MS following the predicted outcomes of the de novo biosynthesis of anthocyanins in S. cerevisiae using a multi-strain co-culture technique.ConclusionsWe propose a novel concept for advancing the heterologous de novo anthocyanin biosynthetic pathway, as well as fundamental information and a theoretical framework for the ensuing optimization of the microbial synthesis of anthocyanins.

Different Nitrogen Consumption Patterns in Low Temperature Fermentations in the Wine Yeast Saccharomyces cerevisiae.

Nowadays, the wine industry carries out fermentations at low temperatures because this oenological practice clearly improves the aromatic complexity of the final wines. In addition, nitrogen content of the must also influences the quality of the wine. In this study, we carried out a phenotypic and fermentative analysis of two industrial wine Saccharomyces cerevisiae strains (P5 and P24) at 15 and 28 °C and three nitrogen concentrations (60, 140 and 300 mg N/L) in synthetic must. Our results show that both parameters, temperature and nitrogen, are interrelated and clearly determine the competitiveness of the wine strains and their ability to adapt at low temperatures. The best adapted strain at low temperatures decreased its competitiveness at lower nitrogen concentrations. In addition, our results show that it is not only the quantity of nitrogen transported that is important but also the quality of the nitrogen source used for wine yeast adaptation at low temperatures. The presence of some amino acids, such as arginine, branched chain amino acids, and some aromatic amino acids can improve the growth and fermentation activity of wine yeasts at low temperatures. These results allow us to better understand the basis of wine yeast adaptation to fermentation conditions, providing important information for winemakers to help them select the most appropriate yeast strain, thus reducing the economic costs associated with long and sluggish fermentations. The correlation between some amino acids and better yeast fermentation performance could be used in the future to design inactive dry yeast enriched in some of these amino acids, which could be added as a nutritional supplement during low temperature fermentations.

A deep learning-guided automated workflow in LipidOz for detailed characterization of fungal fatty acid unsaturation by ozonolysis.

Understanding fungal lipid biology and metabolism is critical for antifungal target discovery as lipids play central roles in cellular processes. Nuances in lipid structural differences can significantly impact their functions, making it necessary to characterize lipids in detail to understand their roles in these complex systems. In particular, lipid double bond (DB) locations are an important component of lipid structure that can only be determined using a few specialized analytical techniques. Ozone-induced dissociation mass spectrometry (OzID-MS) is one such technique that uses ozone to break lipid DBs, producing pairs of characteristic fragments that allow the determination of DB positions. In this work, we apply OzID-MS and LipidOz software to analyze the complex lipids of Saccharomyces cerevisiae yeast strains transformed with different fatty acid desaturases from Histoplasma capsulatum to determine the specific unsaturated lipids produced. The automated data analysis in LipidOz made the determination of DB positions from this large dataset more practical, but manual verification for all targets was still time-consuming. The DL model reduces manual involvement in data analysis, but since it was trained using mammalian lipid extracts, the prediction accuracy on yeast-derived data was reduced. We addressed both shortcomings by retraining the DL model to act as a pre-filter to prioritize targets for automated analysis, providing confident manually verified results but requiring less computational time and manual effort. Our workflow resulted in the determination of detailed DB positions and enzymatic specificity.

Using Extracted Sugars from Spoiled Date Fruits as a Sustainable Feedstock for Ethanol Production by New Yeast Isolates.

This study focuses on investigating sugar recovery from spoiled date fruits (SDF) for sustainable ethanol production using newly isolated yeasts. Upon their isolation from different food products, yeast strains were identified through PCR amplification of the D1/D2 region and subsequent comparison with the GenBank database, confirming isolates KKU30, KKU32, and KKU33 as Saccharomyces cerevisiae; KKU21 as Zygosaccharomyces rouxii; and KKU35m as Meyerozyma guilliermondii. Optimization of sugar extraction from SDF pulp employed response surface methodology (RSM), varying solid loading (20-40%), temperature (20-40 °C), and extraction time (10-30 min). Linear models for sugar concentration (R1) and extraction efficiency (R2) showed relatively high R2 values, indicating a good model fit. Statistical analysis revealed significant effects of temperature and extraction time on extraction efficiency. The results of batch ethanol production from SDF extracts using mono-cultures indicated varying consumption rates of sugars, biomass production, and ethanol yields among strains. Notably, S. cerevisiae strains exhibited rapid sugar consumption and high ethanol productivity, outperforming Z. rouxii and M. guilliermondii, and they were selected for scaling up the process at fed-batch mode in a co-culture. Co-cultivation resulted in complete sugar consumption and higher ethanol yields compared to mono-cultures, whereas the ethanol titer reached 46.8 ± 0.2 g/L.

Bioprocess Optimization by Taguchi Design and Response Surface Analysis for Obtaining Active Yeast Used in Vinification

This study presents the behavior of the identified yeast strain S. cerevisiae, isolated from Busuioacă de Bohotin grapes from the Pietroasa winery, during the process of fermentation to obtain dry active yeast biomass for the winemaking process. In this respect, we promoted an optimization strategy for obtaining active dry yeast biomass. The cultivation conditions for micropilot fermentation (temperature, pH, carbon source, and nitrogen source) were selected and designed according to a Taguchi design with four factors and three levels. Reproducibility testing was conducted under specific fermentation parameters: temperature (32 °C), pH (4.5), carbon source (12%), and nitrogen source (0.7%). Following the optimization process, two combinations of cultivation parameters were selected, and one of them, based on the results, was selected for further analysis. Quantitative data were obtained, showing dry yeast biomass (DCW) at 1.39 g/100 mL and protein content at 45.57%. The active yeast was then used in the winemaking process for Tămâioasă Românească and Busuioacă de Bohotin varieties at Pietroasa winery for validation. This optimization aims to facilitate easy and rapid production of fresh wine yeast tailored to the local winemaking practices of Pietroasa winery, with real application potential in other viticultural areas, aligning with the terroir concept.

Spindle architecture constrains karyotype evolution

The eukaryotic cell division machinery must rapidly and reproducibly duplicate and partition the cell’s chromosomes in a carefully coordinated process. However, chromosome numbers vary dramatically between genomes, even on short evolutionary timescales. We sought to understand how the mitotic machinery senses and responds to karyotypic changes by using a series of budding yeast strains in which the native chromosomes have been successively fused. Using a combination of cell biological profiling, genetic engineering and experimental evolution, we show that chromosome fusions are well tolerated up until a critical point. Cells with fewer than five centromeres lack the necessary number of kinetochore-microtubule attachments needed to counter outward forces in the metaphase spindle, triggering the spindle assembly checkpoint and prolonging metaphase. Our findings demonstrate that spindle architecture is a constraining factor for karyotype evolution.

Improved vectors for retron-mediated CRISPR-Cas9 genome editing in Saccharomyces cerevisiae.

In vivo site-directed mutagenesis is a powerful genetic tool for testing the effects of specific alleles in their normal genomic context. While the budding yeast Saccharomyces cerevisiae possesses classical tools for site-directed mutagenesis, more efficient recent CRISPR-based approaches use Cas 'cutting' combined with homologous recombination of a 'repair' template that introduces the desired edit. However, current approaches are limited for fully prototrophic yeast strains, and rely on relatively low efficiency cloning of short gRNAs. We were thus motivated to simplify the process by combining the gRNA and its cognate repair template in cis on a single oligonucleotide. Moreover, we wished to take advantage of a new approach that uses an E. coli retron (EcRT) to amplify repair templates as multi-copy single-stranded (ms)DNA in vivo , which are more efficient templates for homologous recombination. To this end, we have created a set of plasmids that express Cas9-EcRT, allowing for co-transformation with the gRNA-repair template plasmid in a single step. Our suite of plasmids contains different antibiotic (Nat, Hyg, Kan) or auxotrophic ( HIS3, URA3 ) selectable markers, allowing for editing of fully prototrophic wild yeast strains. In addition to classic galactose induction, we generated a β-estradiol-inducible version of each plasmid to facilitate editing in yeast strains that grow poorly on galactose. The plasmid-based system results in >95% editing efficiencies for point mutations and >50% efficiencies for markerless deletions, in a minimum number of steps and time. We provide a detailed step-by-step guide for how to use this system.

Microbiome of craft hard cheeses from raw goat milk during ripening

The production of craft cheeses from goat milk in small farms in Ukraine is becoming increasingly widespread. The uniqueness of goat cheeses made from raw milk is attributed to the significant diversity of microbiological processes that occur during their ripening, involving natural strains of bacteria, fungi, yeasts, and cheese mites. Therefore, this research aimed to determine the microbial composition of Caciotta and Canestrato goat cheeses during their ripening process. The number of mesophilic aerobic and facultative anaerobic microorganisms (MAFAM) in Caciotta cheese was stable on the 10th day, the 1st, and the 12th month, and decreased by 1.18–1.27 lg CFU/g by the 24th month of ripening. The number of mold fungi and yeasts in Caciotta cheese peaked in the 1st month but they were not detected in the 12th and 24th months of ripening. Lactic acid bacteria in Caciotta cheese formed the basis of MAFAM and were represented by Lactobacillus plantarum on the 10th day and the 1st month of ripening, Lactobacillus brevis and Leuconostoc pseudomesenteroides in the 12th month, and L. brevis and Leuconostoc mesenteroides in the 24th month. In 24-month-ripened Caciotta cheese, Escherichia coli, Enterobacter ludwigii, E. durans, E. faecalis, and E. hirae were detected. Lactic acid bacteria in Canestrato cheese formed the basis of MAFAM and were represented by L. mesenteroides from the 10th day to the 3rd month of age, L. pseudomesenteroides in the 6th month, and L. plantarum in the 12th month. Canestrato cheese was characterized by a significant presence of mold fungi and yeasts in all ripening periods except for the 6th month. In 12-month-ripened Canestrato cheese, Enterobacter cloacae, Bacillus cereus, Enterococcus durans, E. hirae, and E. faecalis were isolated. Cheese mites, Acarus siro, in various stages of development were found in the rind of both cheeses starting from the 6th month of ripening. The results of the researchers provide new data on the microbiome of craft hard cheeses made from raw goat milk and can be used to develop methods for controlling the population size of A. siro mites during their ripening.

Direct transformation of rice straw to electricity and hydrogen by a single yeast strain: Performance and mechanism

Lignocellulosic waste is one of the most abundant renewable energy sources. However, pretreatment or complex microbial consortia are usually required for the biological transformation into energy products. This study demonstrates the direct transformation of raw rice straw biomass into electricity and hydrogen without any pretreatment by employing a single yeast strain, Cystobasidium slooffiae JSUX1, in microbial fuel cells (MFCs). The yeast-MFCs exhibit a maximum power density of 28.56 ± 2.54 mW/m2 with simultaneous production of hydrogen gas (4.9 ± 0.52 L/m3) from raw straw. Further analysis reveals that enzymes secreted by the yeast strain degraded rice straw into sugars or organic acids, serving as fuel for electricity and hydrogen production. In addition, humic acid (HA) and Fe-HA derived from biomass consumption serve as electron mediators for extracellular electron transfer (EET) in MFCs. This study demonstrates the power of the yeast strain for renewable energy recovery from straw, diversifying the toolbox for the lignocellulose industry.

Genome-Wide Isolation of VIN Gene Family and Functional Identification of HpVIN4 in Red Pitaya (Hylocereus polyrhizus)

Soluble sugars, including glucose, fructose and sucrose, are the most important determinants that affect the flavor and quality of red pitaya (Hylocereus polyrhizus) fruit. Vacuolar invertase (VIN), which catalyzes sucrose hydrolysis into glucose and fructose, is a key type of enzyme responsible for soluble sugar metabolism in plant growth and development. Herein, we conducted genome-wide identification, gene expression analysis, subcellular localization and an enzymatic properties assay for the VIN-encoding genes from red pitaya. During red pitaya fruit development towards ripening, the enzymatic activities of VIN showed an up-regulated trend towards ripening. In total, four isoforms (HpVIN1–4) of the VIN-encoding gene were identified from the pitaya genome. Sequence alignment results revealed that the HpVIN1, HpVIN3 and HpVIN4 proteins contained essential motifs for targeting the vacuole and conserved motifs or residues responsible for sucrose binding and hydrolysis. Gene expression pattern analyses revealed that the level of HpVIN4 was obviously increasing during fruit development and acted as the most abundant VIN isoform towards ripening. Subcellular localization detection via transient expression in Arabidopsis thaliana mesophyll protoplasts revealed that the HpVIN4 protein was localized in the vacuole. Growth complementation tests of heterologous expression in the invertase-deficient baker’s yeast strain suggested that the HpVIN4 protein had a sucrose hydrolysis activity and could restore the yeast growth in vivo. The identification of enzymatic properties in vitro demonstrated that the HpVIN4 protein could degrade sucrose into glucose and fructose with an optimum pH of 4.0. Specifically, the HpVIN4 protein had an estimated Km value of 5.15 ± 1.03 mmol·L−1 for sucrose hydrolysis. Ultimately, this study provides a comprehensive understanding of the potential roles of VINs during fruit development and towards ripening and provides functional gene resources for regulating soluble sugar accumulation in red pitaya fruit.

Construction of an amylolytic Saccharomyces cerevisiae strain with high copies of α-amylase and glucoamylase genes integration for bioethanol production from sweet potato residue.

Sweet potato residue (SPR) is the by-product of starch extraction from fresh sweet potatoes and is rich in carbohydrates, making it a suitable substrate for bioethanol production. An amylolytic industrial yeast strain with co-expressing α-amylase and glucoamylase genes would combine enzyme production, SPR hydrolysis, and glucose fermentation into a one-step process. This consolidated bioprocessing (CBP) shows great application potential in the economic production of bioethanol. In this study, a convenient heterologous gene integration method was developed. Eight copies of a Talaromyces emersonii α-amylase expression cassette and eight copies of a Saccharomycopsis fibuligera glucoamylase expression cassette were integrated into the genome of industrial diploid Saccharomyces cerevisiae strain 1974. The resulting recombinant strains exhibited clear transparent zones in the iodine starch plates, and SDS-PAGE analysis indicated that α-amylase and glucoamylase were secreted into the culture medium. Enzymatic activity analysis demonstrated that the optimal temperature for α-amylase and glucoamylase was 60-70°C, and the pH optima for α-amylase and glucoamylase was 4.0 and 5.0, respectively. Initially, soluble corn starch with a concentration of 100 g/L was initially used to evaluate the ethanol production capability of recombinant amylolytic S. cerevisiae strains. After 7 days of CBP fermentation, the α-amylase-expressing strain 1974-temA and the glucoamylase-expressing strain 1974-GA produced 33.03 and 28.37 g/L ethanol, respectively. However, the 1974-GA-temA strain, which expressed α-amylase and glucoamylase, produced 42.22 g/L ethanol, corresponding to 70.59% of the theoretical yield. Subsequently, fermentation was conducted using the amylolytic strain 1974-GA-temA without the addition of exogenous α-amylase and glucoamylase, which resulted in the production of 32.15 g/L ethanol with an ethanol yield of 0.30 g/g. The addition of 20% glucoamylase (60 U/g SPR) increased ethanol concentration to 50.55 g/L, corresponding to a theoretical yield of 93.23%, which was comparable to the ethanol production observed with the addition of 100% α-amylase and glucoamylase. The recombinant amylolytic strains constructed in this study will facilitate the advancement of CBP fermentation of SPR for the production of bioethanol.

Establishment of an in vitro evaluation method for immunomodulatory functions of yeast strains.

Saccharomyces cerevisiae, a widely studied yeast known for its industrial applications, is increasingly recognized for its potential in immunomodulation. This study aimed to systematically analyze and compare the immune-modulating properties of various S. cerevisiae strains under controlled experimental conditions. Three essential signals crucial for immune response activation were evaluated to elucidate the immunological responses elicited by these strains, i.e., dendritic cells (DC) cytokine secretion profiles, maturation status, and T cell polarization. Analysis of DC cytokine secretion profiles and maturation status revealed that all tested yeast strains induced DC activation, characterized by significant IL-6 secretion and modest IL-10 induction, as well as upregulation of MHC II molecules. Additionally, strain-specific effects were observed, particularly, strain AJM109 and Y1383 uniquely enhanced CD86 and PD-L1 expression, respectively, suggesting differential impacts on DC co-stimulatory signaling. Furthermore, strain Y1383 showed a unique capacity to support Treg-mediated immune suppression, demonstrating its potential in immune tolerance induction. These findings underscore the complexity of S. cerevisiae-based immune modulation and emphasize the importance of standardized evaluation methods to distinguish their specific immunological effects.

Investigating biological mechanisms of colour changes in sustainable food systems: The role of Starmerella bacillaris in white wine colouration using a combination of genomic and biostatistics strategies

This study explores the biological mechanisms behind colour changes in white wine fermentation using different strains of Starmerella bacillaris. We combined food engineering, genomics, machine learning, and physicochemical analyses to examine interactions between S. bacillaris and Saccharomyces cerevisiae. Significant differences in total polyphenol content were observed, with S. bacillaris fermentation yielding 6 % higher polyphenol content compared to S. cerevisiae EC1118. Genomic analysis identified 12 genes in S. bacillaris with high variant counts that could impact phenotypic properties related to wine color. Notably, SNP analysis revealed numerous missense and synonymous variants, as well as stop-gained and start-lost variants between PAS13 and FRI751, suggesting changes in metabolic pathways affecting pigment production. Besides that, high upstream gene variants in SSK1 and HIP1R indicated potential regulatory changes influencing gene expression. Fermentation trials revealed FRI751 consistently showed high antioxidant activity and polyphenol content (Total Polyphenol: 299.33 ± 3.51 mg GAE/L, DPPH: 1.09 ± 0.01 mmol TE/L, FRAP: 0.95 ± 0.02 mmol TE/L). PAS13 exhibited a balanced profile, while EC1118 had lower values, indicating moderate antioxidant activity. The Weibull model effectively captured nitrogen consumption dynamics, with EC1118 serving as a reliable benchmark. The scale parameter delta for EC1118 was 23.04 ± 2.63, indicating moderate variability in event times. These findings highlight S. bacillaris as a valuable component in sustainable winemaking, offering an alternative to chemical additives for maintaining wine quality and enhancing colours profiles. This study provides insights into the biotechnological and fermented food systems applications of yeast strains in improving food sustainability and supply chain, opening new avenues in food engineering and microbiology.

Biological and chemical enhancements of Elaeocarpus sylvestris var. ellipticus through fermentation: Implications for therapeutic and industrial applications

This study aimed to evaluate the biological and chemical improvements that take place during the yeast fermentation of hot water-extracted Elaeocarpus sylvestris (HES). HES was diluted with sterile distilled water to a final concentration of 1:200 (v/v), followed by the inoculation of Pichia fermentans (PF) and Saccharomyces cerevisiae (SC) were inoculated as starters. The fermentation by yeast strains proceeded for five days, during which the viable cell count and pH were monitored. The radical scavenging activity was assessed using DPPH and ABTS assays. The impact of HES on proinflammatory cytokines in RAW 264.7 cells and cytotoxicity in HT-29, MCF-7, and INT407 cells was examined. Changes in metabolic profile during fermentation were analyzed using GC-TOF-MS and UPLC-Orbitrap-MS/MS. HES fermented with PF and SC maintained viable cell counts throughout the 5-day fermentation period. The pH levels were consistently within the range of 3.62 ± 0.03 to 3.65 ± 0.15. The expression of TNF-α and IL-6 significantly decreased at all concentrations (31–500 mg/mL) in RAW cells treated with lipopolysaccharide and HES, with cytokine expression levels returning to baseline levels. The cell viability of INT407 significantly increased following HES treatment (p < 0.05). Fermentation of HES with PF or SC led to significant changes in the composition ratios of carboxylic acids and derivatives, and organooxygen compounds. The HES extract demonstrates potential applicability as a raw material with antioxidative, anti-inflammatory, and anticancer properties for applications in the food and cosmetic industries.

European farmhouse brewing yeasts form a distinct genetic group

The brewing industry is constantly evolving, driven by the quest for novel flavours and fermentation characteristics that cater to evolving consumer preferences. This study explores the genetic and phenotypic diversity of European farmhouse yeasts, traditionally used in rural brewing practices and maintained outside of pure culture industrial yeast selection. We isolated landrace brewing yeast strains from diverse geographical locations across Europe, including Norway, Lithuania, Latvia, and Russia, and also included African farmhouse brewing strains from Ghana. Our genomic analysis using long-read and short-read whole genome sequencing uncovered a genetically distinct group that diverges from industrial brewing yeasts. This group, which is closely related to ale brewing strains, is preliminarily named the ‘European Farmhouse’ group and shows greater predicted admixture from Asian fermentation strains. Through genomic and phenotypic analyses, including flavour metabolite analysis via headspace gas chromatography-mass spectrometry, sugar metabolite analysis via high-performance liquid chromatography, and wort fermentation analysis, we found a broad spectrum of fermentation capabilities, from rapid and efficient fermentation to unique aroma and flavour compound profiles, potentially offering novel traits for brewing applications. This study highlights the importance of preservation of brewing cultural heritage knowledge and resources including yeast cultures.Key points• A large set of geographically diverse farmhouse brewing strains were characterized• Norwegian and Baltic farmhouse brewing strains form a distinct genetic group• Farmhouse strains show considerable diversity in fermentation and flavour formation

Cyberlindnera qingyuanensis f.a., sp. nov., a yeast species isolated from rotting wood.

Two yeast strains were isolated from rotting wood samples collected on Qingyuan Mountain, Fujian Province, PR China. Phylogenetic analysis, based on the concatenated sequences of the internal transcribed spacer (ITS) region and the D1/D2 domain of the large subunit rRNA gene, revealed that these two strains represent a novel species of the genus Cyberlindnera. The proposed name for this new species is Cyberlindnera qingyuanensis f.a., sp. nov. (holotype: GDMCC 2.300; ex-type: PYCC 9925) although the formation of ascospores was not observed. The novel species differs from its close relative Cyberlindnera galapagoensis by 7.7% sequence divergence (37 substitutions and seven indels) in the D1/D2 domain and 9.7% sequence divergence (42 substitutions and 34 indels) in the ITS region, respectively. Additionally, Cyb. qingyuanensis differs from its close relative Cyb. galapagoensis by its ability to grow in cellobiose, l-rhamnose, ribitol, galactitol, and dl-lactate, its growth at 37 °C, and its inability to ferment raffinose. The Mycobank number is MB 854693.

Engineering a GPCR-based yeast biosensor for a highly sensitive melatonin detection from fermented beverages

Melatonin is a multifunctional molecule with diverse biological roles that holds great value as a health-promoting bioactive molecule in any food product and yeast’s ability to produce it has been extensively demonstrated in the last decade. However, its quantification presents costly analytical challenges due to the usual low concentrations found as the result of yeast metabolism. This study addresses these analytical challenges by optimizing a yeast biosensor based on G protein-coupled receptors (GPCR) for melatonin detection and quantitation. Strategic genetic modifications were employed to significantly enhance its sensitivity and fluorescent signal output, making it suitable for detection of yeast-produced melatonin. The optimized biosensor demonstrated significantly improved sensitivity and fluorescence, enabling the screening of 101 yeast strains and the detection of melatonin in various wine samples. This biosensor’s efficacy in quantifying melatonin in yeast growth media underscores its utility in exploring melatonin production dynamics and potential applications in functional food development. This study provides a new analytical approach that allows a rapid and cost-effective melatonin analysis to reach deeper insights into the bioactivity of melatonin in fermented products and its implications for human health. These findings highlight the broader potential of biosensor technology in streamlining analytical processes in fermentation science.