Bayanus Strains Research Articles

Chromosome-level subgenome-aware de novo assembly provides insight into Saccharomyces bayanus genome divergence after hybridization.

Interspecies hybridization is prevalent in various eukaryotic lineages and plays important roles in phenotypic diversification, adaptation, and speciation. To better understand the changes that occurred in the different subgenomes of a hybrid species and how they facilitate adaptation, we have completed chromosome-level de novo assemblies of all chromosomes for a recently formed hybrid yeast, Saccharomyces bayanus strain CBS380, using Oxford Nanopore Technologies' MinION long-read sequencing. We characterize the S. bayanus genome and compare it with its parent species, Saccharomyces uvarum and Saccharomyces eubayanus, and other S. bayanus genomes to better understand genome evolution after a relatively recent hybridization event. We observe multiple recombination events between the subgenomes in each chromosome, followed by loss of heterozygosity (LOH) in nine chromosome pairs. In addition to maintaining nearly all gene content and synteny from its parental genomes, S. bayanus has acquired many genes from other yeast species, primarily through the introgression of Saccharomyces cerevisiae, such as those involved in the maltose metabolism. Finally, the patterns of recombination and LOH suggest an allotetraploid origin of S. bayanus The gene acquisition and rapid LOH in the hybrid genome probably facilitated its adaptation to maltose brewing environments and mitigated the maladaptive effect of hybridization. This paper describes the first in-depth study using long-read sequencing technology of an S. bayanus hybrid genome, which may serve as an excellent reference for future studies of this important yeast and other yeast strains.

Highly efficient production of 2-phenylethanol by wild-type Saccharomyces bayanus strain

2-Phenylethanol (2-PE) is a highly valuable aromatic alcohol utilized in fragrance, cosmetics and food industries. Due to the toxic by-products from chemical synthesis and the low productivity of the extraction method, bioproduction of 2-PE by yeast is considered promising. In this study, a wild-type Saccharomyces bayanus L1 strain producing 2-PE was isolated from soy sauce mash. Transcriptional analysis showed that 2-PE was synthesized via the Ehrlich pathway and Shikimate pathway in S. bayanus L1. By improving the fermentation conditions in shaking flasks, the maximum 2-PE titer reached 4.2 g/L with a productivity of 0.058 g/L/h within 72 h. In fed-batch fermentation, S. bayanus L1 strain produced 6.5 g/L of 2-PE within 60 h, achieving a productivity of 0.108 g/L/h. These findings suggest that S. bayanus L1 strain is an efficient 2-PE producer, paving the way for highly efficient 2-PE production.

Influence of Saccharomyces pastorianus and Saccharomyces bayanus Inoculation Ratio to Oenological Characteristics of Sauvignon Blanc Wine

The aim of the present study was to assess the effect of the inoculation ratio between Saccharomyces pastorianus strain SP2 and S. bayanus strain BCS103 on the enological properties and aroma profile of Sauvignon Blanc wines. For that purpose, a total of eight different fermentation trials on Sauvignon Blanc must took place. These included spontaneous fermentation as well as inoculation with pure and mixed cultures of the S. pastorianus and S. bayanus strains. The mixed cultures contained different proportions of the two strains (S. pastorianus SP2 to S. bayanus BCS103: 99–1%, 97–3%, 95–5%, 90–10% and 70–30% w/w). Classical oenological analyses were employed to assess the course of fermentation and classical microbiological enumeration combined with inter-delta sequence profile analysis was used for yeast population dynamics estimation. The volatile compounds of each wine were analyzed with GC/MS. The fermentation was completed between 11 and 13 days, while the inoculation ratio significantly affected the chemical composition and the sensorial evaluation of the resulting wines. Based on the sensory evaluation, the least-appreciated Sauvignon Blanc wine was the one resulting from spontaneous fermentation, and the higher the ratio of the S. bayanus strain in the inoculum, the higher the level of appreciation of the wine.

Comparison of the influence of Saccharomyces pastorianus to Saccharomyces cerevisiae and Saccharomyces bayanus inoculation ratio to oenological characteristics of Sauvignon Blanc wine

The aim of our work was to evaluate the impact of different fermentation schemes by using mixed and pure cultures of S. pastorianus and S. cerevisiae or S. bayanus. For the mixed fermentation schemes, one strain of S. pastorianus has been inoculated under different proportions (99%/1%, 97%/3%, 95%/5%, 90%/10% and 70%/30% w/w) in co-inoculation with two commercial strains of S. cerevisiae and one commercial Saccharomyces bayanus strain. The fermentation kinetics has been controlled by density measurement and classical oenological analyses were performed based on OIV analytical methods. The population dynamics was evaluated by the specific interdelta PCR reaction of the Saccharomyces species in the beginning and in the end of the fermentation process. Volatile compounds of the wine aroma, such as esters, higher alcohols and thiols were analyzed by GC/MS. Sensory assessment by trained panel was carried out for all wines. The wines fermented with S. pastorianus, either in pure or mixed cultures, were characterized by significantly lower acetic acid production and higher malic acid degradation when compared to the wines fermented with S. cerevisiae strains. The presence of S. pastorianus strain enhanced the production of the varietal thiols when compared to the samples fermented with the S. cerevisiae pure cultures. The wines produced by the S. bayanus or cerevisiae monocultures and the ones produced by the co-culture with S. pastorianus at 70%-30% ratio (S. pastorianus to S. bayanus or cerevisiae) were overall better rated from a sensory point of view.

Selection of Saccharomyces bayanus Strains with High Pectinolytic Activity and Phylogenetic Analysis of PGU Genes

Selection of Saccharomyces bayanus Strains with High Pectinolytic Activity and Phylogenetic Analysis of PGU Genes

Comparison Of Commercial Yeast Strains In Production Of Meads With Africanized Bee’s And Stingless Bee’s Honey

ABSTRACT The aim of this work was to elaborate meads from the honeys of Apis mellifera and Melipona subnitida bees, fermented with Saccharomyces cerevisiae and Saccharomyces bayanus strains. The honeys were submitted to physicochemical analyses. The fermentations were carried out at 25°C for four months and the beverages were matured at 10°C for two months. The honeys showed different physicochemical characteristics. The highest DPPH radical inhibition percentages were observed in meads produced with Apis mellifera honey, while the Saccharomyces bayanus yeast was the most suitable for mead production due to the high content of ethanol developed.

Selection of low nitrogen demand yeast strains and their impact on the physicochemical and volatile composition of mead.

Mead is an ancient alcoholic beverage produced through the fermentation of a diluted solution of honey. Due to the peculiar and varied composition of honey, mead production faces several problems, such as slow or stuck fermentations mainly due to the low nitrogen concentration, lack of uniformity of the final product and the production of unpleasant aromas. In this context, this work aimed to select low nitrogen-demand yeast strains and evaluate their potential for the production of mead. Therefore, among 21 commercial wine yeast strains, 5 were selected based on their fermentative behavior at low assimilable nitrogen concentrations. The selected strains were further evaluated for their contributions in meads produced with limited nitrogen availability, and the results showed significant differences on some physicochemical parameters like biomass production, residual sugars, glycerol concentration, and fermentative rate. Moreover, meads obtained with selected strains differed in the concentration of several volatile compounds. The volatile compounds concentration and the principal component analysis based on odor activity values allowed separating strains into three groups. In general, S. cerevisiae var bayanus strains (QA23, Spark, and AWRI-R2) were the largest producers of aromatic compounds, particularly those with floral and fruity descriptors. The selection of yeast strains with low nitrogen-demand and different volatile compounds production can be explored by mead makers to limit fermentation problems and obtain characteristic products.

Mannoprotein Content and Volatile Molecule Profiles of Trebbiano Wines Obtained by Saccharomyces cerevisiae and Saccharomyces bayanus Strains

The production of volatile compounds has become one of the major technological features for yeast selection. In fact, although the aromatic profile of the wine is the sum of varietal-, pre-, post-, and fermentative-aroma compound, yeasts affect the quality of the grape from maturation throughout fermentation, metabolizing sugars and other components into alcohols, esters, organic acids, and aldehydes. Among the new technological features, the production of mannoproteins has gained interest. From this perspective, the main aim of this work was to characterize 9 strains of Saccharomyces cerevisiae and 1 of Saccharomyces bayanus for their volatile profiles and the release of mannoproteins. The strains were inoculated in Trebbiano musts and incubated at 15 °C; at the end of fermentation the wines were evaluated by GC/MS/SPME for their volatile profiles and mannoprotein content by enzymatic assay. The strains were inoculated at level ranging between 4.9 and 6.3 log CFU/mL but only the strains L318 and 12233X6167 were able to reach values of 7.5 log CFU/mL. The aromatic profiles resulted in a strain-specific fingerprinting. According to the principal component analysis, the wines produced by the strains L288, L234, and L318 were characterized by the presence of propanoic acid, butanol, octanoic acid, and 3 methyl pentanol while the wine obtained by the strain 12233x35G2 was characterized by the presence of propanoic acid, butanol, octanoic acid and 3 methyl pentanol while the strain 12233x35G2 was characterized by the presence of decanoic acid ethyl ester, heptanoic acid ethyl ester, and acetic acid 2 phenetyl ester. Regarding mannoproteins, the highest concentration was achieved by strain12233x6167 (104 mg/L). The data allowed to select the strains endowed with the best fermentation performances in terms of aroma and mannoproteins release.

Development of vinegar obtained from lemon juice: Optimization and chemical characterization of the process

A research on the production of lemon vinegar directly from lemon juice was conducted. For the alcoholic fermentation, two different strains of Saccharomyces cerevisiae, as well as two types of cultures (submerged culture and yeasts immobilized in alginate beads) were used. A microbiological control was also implemented during this stage. Acetic fermentation variables were optimized for a semi-continuous process. The whole process was monitored by means of volatile (SBSE/GC-MS), polyphenolic composition (UPLC-DAD), and sensory analysis was also conducted for the optimization procedure. The best conditions for alcoholic fermentation were obtained when Saccharomyces cerevisiae var. bayanus strain was used under a submerged culture, where a content of 13.53 mL ethanol/100 mL of wine was obtained. With regards to acetic fermentation, the use of an unloading volume of 33.33% of the total volume produced lemon vinegar in 20–24 h with an acidity of 13.29 g/100 mL of vinegar (expressed as acetic acid). The chemical monitoring of the process demonstrated that the majority of volatile compounds and polyphenols studied decreased during alcoholic and acetic fermentations. Multivariate statistical analysis such as principal component analysis allowed the classification of the samples according to the matrix (juice, wine and vinegar).

Characterization of Saccharomyces bayanus CN1 for Fermenting Partially Dehydrated Grapes Grown in Cool Climate Winemaking Regions

This project aims to characterize and define an autochthonous yeast, Saccharomyces bayanus CN1, for wine production from partially dehydrated grapes. The yeast was identified via PCR and Basic Local Alignment Search Tool (BLAST) analysis as Saccharomyces bayanus, and then subsequently used in fermentations using partially dehydrated or control grapes. Wine grapes were dried to 28.0°Brix from the control grapes at a regular harvest of 23.0°Brix. Both the partially dehydrated and control grapes were then vinified with each of two yeast strains, S. bayanus CN1 and S. cerevisiae EC1118, which is a common yeast used for making wine from partially dehydrated grapes. Chemical analysis gas chromatography-flame ionization detector (GC-FID) and enzymatic) of wines at each starting sugar level showed that CN1 produced comparable ethanol levels to EC1118, while producing higher levels of glycerol, but lower levels of oxidative compounds (acetic acid, ethyl acetate, and acetaldehyde) compared to EC1118. Yeast choice impacted the wine hue; the degree of red pigment coloration and total red pigment concentration differed between yeasts. A sensory triangle test (n = 40) showed that wines made from different starting sugar concentrations and yeast strains both differed significantly. This newly identified S. bayanus strain appears to be well-suited for this style of wine production from partially dehydrated grapes by reducing the oxidative compounds in the wine, with potential commercial application for cool climate wine regions.

Influence of the method of obtaining freeze-enriched juices and year of harvest on the chemical and sensory characteristics of Asturian ice ciders

Ice cider is a special product made from apple juices enriched by freezing. In this paper, the method of obtaining the ice juices (cryo-extraction and exhaustion) and the year of harvest have been evaluated. For this purpose, a controlled raw apple mixture and an autochthonous Saccharomyces bayanus strain were used throughout the study. Both the enrichment system and the year of harvest significantly influenced the levels of total phenols, sucrose, malic acid, ethyl acetate and 2-phenylethanol. The ciders made by cryo-extraction presented the higher sugar/acidity and sugar/polyphenol ratios. These ciders were more fruity, less astringent and scored better for quality than those obtained by exhaustion. Additionally, a preliminary assay of juice enrichment by cryo-concentration is described. The corresponding ciders presented higher methanol and lower 2-phenylethanol contents than those obtained by the cryo-extraction and exhaustion methods.

A Future Place for Saccharomyces Mixtures and Hybrids in Wine Making

Each year, winemakers can face sluggish or stuck fermentations during wine making, especially when a spontaneous fermentation is performed, even if strains of the classical wine yeast Saccharomyces cerevisiae are applied. Problems are inevitable when low ammonium concentrations (<160 mg L−1 grape must) or an excess of fructose compared to glucose are observed during grape must fermentation. S. cerevisiae strains cannot use all kinds of amino acids as the sole nitrogen source but usually need free ammonium (optimal concentration: 600 mg L−1 grape must). It preferably consumes glucose, leading often to an excess of fructose in the fermenting must, which contains glucose and fructose in an equal ratio at the beginning of fermentation. Yeast hybrids have been isolated from wines several times and different strains are already commercially available. The united properties of the parent strains can provide advantages under sophisticated fermentation conditions. However, the involvement of a hybrid yeast for the rectification of fermentation disorders in spontaneous fermentations has only been described recently in the literature. Recent investigations have provided convincing evidence that fermentation problems can be overcome when must fermentations are successively performed with Saccharomyces bayanus strain HL 77 and the triple hybrid S. cerevisiae × Saccharomyces kudriavzevii × S. bayanus strain HL 78. The triple hybrid strain HL 78 uses amino acids as a nitrogen source in the absence of ammonium and it also exhibits a fructophilic character with an enhanced uptake of fructose in comparison to glucose. The application of genetically modified yeast strains is not allowed for starter cultures in wine making, but the usage of yeast mixtures and hybrid strains could be a promising tool for winemakers to solve fermentation problems during spontaneous fermentation or for the creation of novel wine types with desired sensory characteristics under more challenging conditions, especially when the composition of the must components is not optimal because of, e.g., critical climatic or soil conditions.

Evaluation of autochthonous Saccharomyces bayanus strains under stress conditions for making ice ciders

The product diversification policy being carried out by the Asturian cider industry includes the development of beverages similar to so-called ice ciders. During apple juice fermentations, yeast cells are affected by several stress conditions. In this study, 74 Saccharomyces bayanus strains isolated from Asturian cider, have been analyzed in synthetic media for their growth ability, sugar fermentation capacity and acetic acid production under the stress conditions that occurr during the production of ice cider. According to the data obtained 23 strains high proliferation capabilities, sugar fermentation capacity and low acetic acid production have been differentiated. Ten strains were chosen to produce ice ciders from apple juice (31.8 ºBrix) at 12 °C. The products obtained were characterized by not having developed the malolactic conversion and their low contents of acetic acid, methanol and ethyl acetate. Significant differences among ciders were detected for alcoholic degree, total acidity, and contents of glycerol, pyruvic, fumaric and shikimic acids due to the yeast strain used. A Multiple Correspondence Analysis showed four strains associated with sensory quality variables. Our results open up the possibility of using autochthonous S. bayanus strains as starters in the making of Asturian ice ciders.

Characterization of Saccharomyces uvarum (Beijerinck, 1898) and related hybrids: assessment of molecular markers that predict the parent and hybrid genomes and a proposal to name yeast hybrids.

The use of the nuclear DNA reassociation technique has led taxonomists to consider Saccharomyces uvarum a synonym of S. bayanus. The latter, however, is not a species but a hybrid harbouring S. eubayanus (Seu) and S. uvarum (Su) subgenomes with a minor DNA contribution from S. cerevisiae (Sc). To recognize genetically pure lines of S. uvarum and putative interspecies hybrids among so-called S. bayanus strains present in public culture collections, we propose the use of four markers that were defined from the S. bayanus CBS 380T composite genome, namely SeuNTS2 (rDNA), ScMAL31, MTY1 and SuMEL1. Saccharomyces carlsbergensis CBS 1513 was found to be similar to S. bayanus except that it carries the SeuMEL1 allele. Different marker combinations revealed that among 33 strains examined only a few were similar to CBS 380T, but many pure S. uvarum lines and putative Su/Seu-related hybrids occurred. Our results demonstrated that these hybrids were erroneously considered authentic S. bayanus and therefore the varietal state 'Saccharomyces bayanus var. uvarum comb. nov. Naumov' is not valid. Our markers constitute a tool to get insights into the genomic makeup of Saccharomyces interspecies hybrids. We also make a proposal to name those hybrids that may also be applicable to other fungal hybrids.

Yeast Autolysis in Sparkling Wine Aging: Use of Killer and Sensitive Saccharomyces cerevisiae Strains in Co-Culture.

Sparkling wines produced by traditional method owe their characteristics to secondary fermentation and maturation that occur during a slow ageing in bottles. Yeast autolysis plays an important role during the sparkling wine aging. Using a combination of killer and sensitive yeasts is possible to accelerate yeast autolysis and reduce maturing time. killer and sensitive Saccharomyces cerevisiae strains, separately and in co-cultures, were inoculated in base wine and bottled on pilot-plant scale. Commercial Saccaromyces bayanus strain was also investigated. Protein free amino acid and polysaccharides contents and sensory analysis were determined on the wine samples at 3, 6 and 9 months of aging. Yeast autolysis that occurs during the production of sparkling wines, obtained with co-cultures of killer and sensitive strains, has influenced free amino acids, total protein and polysaccharides content after 3 months aging time: sparkling wines, produced without the use of these yeasts, have reached the same results only after 9 months aging time. These results demonstrate that killer and sensitive yeasts in co-culture can accelerate the onset of autolysis in enological conditions, and has a positive effect on the quality of the aroma and flavor of sparkling wine. This paper offers an interesting biotechnological method to reduce production time of sparkling wine with economical benefits for the producers. We revised all patents relating to sparkling wine considering only those of interest for our study.

Stuck at work? Quantitative proteomics of environmental wine yeast strains reveals the natural mechanism of overcoming stuck fermentation.

During fermentation oenological yeast cells are subjected to a number of different stress conditions and must respond rapidly to the continuously changing environment of this harsh ecological niche. In this study we gained more insights into the cell adaptation mechanisms by linking proteome monitoring with knowledge on physiological behaviour of different strains during fermentation under model winemaking conditions. We used 2D-DIGE technology to monitor the proteome evolution of two newly discovered environmental yeast strains Saccharomyces bayanus and triple hybrid Saccharomyces cerevisiae × Saccharomyces kudriavzevii × S. bayanus and compared them to data obtained for the commercially available S. cerevisiae strain. All strains examined showed (i) different fermentative behaviour, (ii) stress resistance as well as (iii) susceptibility to stuck fermentation which was reflected in significant differences in protein expression levels. During our research we identified differentially expressed proteins in 155 gel spots which correspond to 70 different protein functions. Differences of expression between strains were observed mainly among proteins involved in stress response, proteins degradation pathways, cell redox homeostasis and amino acids biosynthesis. Interestingly, the newly discovered triple hybrid S. cerevisiae × S. kudriavzevii × S. bayanus strain which has the ability to naturally restart stuck fermentation showed a very strong induction of expression of two proteolytic enzymes: Pep4 and Prc1 that appear as numerous isoforms on the gel image and which may be the key to its unique properties. This study is an important step towards the better understanding of wine fermentations at a molecular level.

2μ plasmid in Saccharomyces species and in Saccharomyces cerevisiae.

We determined that extrachromosomal 2μ plasmid was present in 67 of the Saccharomyces cerevisiae 100-genome strains; in addition to variation in the size and copy number of 2μ, we identified three distinct classes of 2μ. We identified 2μ presence/absence and class associations with populations, clinical origin and nuclear genotypes. We also screened genome sequences of S. paradoxus, S. kudriavzevii, S. uvarum, S. eubayanus, S. mikatae, S. arboricolus and S. bayanus strains for both integrated and extrachromosomal 2μ. Similar to S. cerevisiae, we found no integrated 2μ sequences in any S. paradoxus strains. However, we identified part of 2μ integrated into the genomes of some S. uvarum, S. kudriavzevii, S. mikatae and S. bayanus strains, which were distinct from each other and from all extrachromosomal 2μ. We identified extrachromosomal 2μ in one S. paradoxus, one S. eubayanus, two S. bayanus and 13 S. uvarum strains. The extrachromosomal 2μ in S. paradoxus, S. eubayanus and S. cerevisiae were distinct from each other. In contrast, the extrachromosomal 2μ in S. bayanus and S. uvarum strains were identical with each other and with one of the three classes of S. cerevisiae 2μ, consistent with interspecific transfer.

Influence of Saccharomyces cerevisiae strain on the profile of volatile organic compounds of blossom honey mead

The influence of yeast strain on the volatile profile of meads fermented from blossom honey using three different Saccharomyces cerevisiae var. bayanus strains was evaluated. Meads were analysed by methods of basic chemical analysis and gas chromatography after 15 days of fermentation. Individual yeast strains produced various metabolites in different concentrations under the same fermentation conditions which significantly influenced the final secondary aroma of mead. Higher concentrations of acetaldehyde and 1-propanol, associated with S. cerevisiae var. bayanus MM-R2 considerably distinguished this strain from the others, whereas the difference between strains S. cerevisiae var. bayanus FM-R-Fix1 and MT-R1B was characterised by the production of ethyl hexanoate, ethyl octanoate (FM-R-Fix1), and isobutyl alcohol (MT-R1B).

Isolating Wine Yeasts that are Specific to the Apold Region and Identifying them through RFLP Genetic Methods

The present study aims at isolating, identifying and selecting autochthonous wine yeast strains with a view to establish a crop bank specific to the Apold area. 569 wine yeast strains were isolated during the alcoholic fermentation of must from the Apold area, 458 were identified through cultural methods and with the help of the API 20 C AUX test (Biomeriux, France). Six yeast strains (A87, A169, A296, A314, A132 and A413) were genetically identified through the PCR-ITS RFLP method of the 5.8S-ITS segment; the resulting four strains were Saccharomyces cerevisiae - A87, A169, A296, A314 - and two Saccharomyces bayanus strains - A132 și A413. The strains we identified constitute a base for the multiplication of indigenous species with a view to obtain authentic wines that are typical to their area of origin.

An Exemplary Model Study for Overcoming Stuck Fermentation during Spontaneous Fermentation with the Aid of a Saccharomyces Triple Hybrid

Sluggish or stuck fermentations cause significant financial losses for winemakers each year. In order to investigate the reasons for problems during spontaneous fermentation of Riesling must in a well-known German vineyard of the lower Moselle, yeast strains involved in must fermentation were identified during winemaking in the two years 2011 and 2012. Identification of the yeast isolates was performed by applying analyses of the ITS-1-5.8-ITS2 region and restriction fragment analyses of different gene sequences. It revealed that Saccharomyces (S.) bayanus and not Saccharomyces cerevisiae was the main fermenting yeast. Either S. bayanus finished the fermentation or led to stuck fermentation. After about four weeks of stuck, fermentation continued spontaneously S. bayanus was replaced by the triple hybrid S. cerevisiae × S. kudriavzevii × S. bayanus. The triple hybrid strain HL 78 was able to utilize fructose more efficiently than S. bayanus strain HL 77. The fructophilic character of the triple hybrid strain correlated with an enhanced uptake of radiolabeled fructose compared to glucose. In contrast to the usual starter culture S. cerevisiae, both isolates, S. bayanus strain HL 77 and the triple hybrid strain HL 78, could grow in the absence of ammonium when amino acids were present. However, the triple hybrid was able to consume glucose and especially fructose at lower amino acid concentrations. Thus, the triple hybrid strain HL 78 was a suitable strain to overcome stuck fermentation without changing the fermentation conditions and the aroma profile desired by the selected winery. It has already been successfully used to restart stuck fermentation. The procedure described here could be a useful approach for wine makers facing problems during spontaneous fermentation. Since the application of genetically modified yeast strains is not allowed for starter culture, based on these studies we suggest the generation of hybrid strains with desired phenotypical features from mother yeasts strains/species of a certain winery and their application in case that during a spontaneous fermentations a sluggish or stuck fermentation is observed.