Hanseniaspora Species Research Articles

Contributions of Hanseniaspora species to Pinot Noir microbial terroir in Oregon's Willamette Valley wine region.

Hanseniaspora yeasts are frequently found in uninoculated wine fermentations, and depending upon the species present, their contributions to the wine may be positive or negative. We found that in Oregon's Willamette Valley, the most common species of Hanseniaspora in Pinot Noir vineyards was the known spoilage organism, H. uvarum. This species was one of the strongest contributors to differences in fungal communities between different vineyards and was enriched during typical Pinot Noir processing. These results support Hanseniaspora as an integral and functional component of vineyard "microbial terroir" within Oregon.

Detection of Hanseniaspora opuntiae in anovaginal samples of pregnant women in Rio de Janeiro, Brazil-a case report.

In this study, we report the first isolation of Hanseniaspora opuntiae obtained from four pregnant women in Brazil. Clinical isolates were obtained from four samples taken between 35 and 37 gestational weeks, as part of the routine antenatal care for maternal colonization screening for Streptococcus agalactiae group B. The patients were immunocompetent, with two of them diagnosed with gestational diabetes mellitus. Species identification was performed by MALDI-TOF MS and rDNA sequencing. While Hanseniaspora species have not traditionally been considered a typical opportunist pathogen, our findings emphasize the importance of investigating and screening for Hanseniaspora in pregnant populations, highlighting H. opuntiae as a potential agent of human infections.

Yeast species of diverse functionality in health sciences: A concise report

The health of a living being is of paramount importance in productivity, which may be human productivity, animal productivity, crop plant productivity, or aquaculture productivity. Among the several pathogenic entities responsible to affect health, yeast is emerging as an important pathogen, while on the other hand; it is also being used as a probiotic agent in treating certain diseases of human and animals. These single-cell budding microorganisms are inhabitant of soil, water, and environment, and are associated with decomposing and fermenting material, living being, and agricultural crops and produce. These are specific in their association, activities, and role and belong to different genera/species. The most common yeast species that act as agents of human disease are species of Candida particularly Candida albicans, Candida tropicalis, Candida glabrata, Candida parapsilosis, and Cryptococcus neoformans. Similarly, the most evident emerging yeast pathogens are Malassezia furfur, Trichosporon beigelii, Rhodotorula species, Hansenula anomala, Candida lusitaniae, and Candida krusei. The yeast responsible for animal infection and diseases mostly belongs to Candida species, the most important being C. albicans, C. glabrata, C. parapsilosis, C. tropicalis, and C.krusei besides some other candida species to cause various types of infectious diseases in animals. Cryptococcus neoformis and Cryptococcus gattii are other two important yeast of the Cryptococcus genus implicated in animal diseases. Other cryptococcus species like C. laurentii and C. albidus affect immunocompromised animals. The yeast Malassezia is also reported to cause disease in animals. Bird’s infections are mostly reported to cause by species of Candida. The yeast species useful as probiotics in the treatment of human health ailments includes Saccharomyces boulardii, while in the use of animal and poultry health is Saccharomyces cerevisiae. The yeast species known to cause disease infection in Marine animals include the ascomycetous yeasts which comprise 9 known species from four genera (viz. Candida, Meyerozyma, Kodamaea, and Wickerhamomyces), and the basidiomycetous yeasts comprises 10 known species from eight genera (viz. Vishniacozyma, Filobasidium, Naganishia, Papiliotrema, Sterigmatomyces, Cystobasidium, Rhodotorula, and Rhodosporidiobolus). The species with the highest occurrence is Rhodotorula mucilaginosa. The yeast species involved in plant growth-promoting activities directly or indirectly includes the species of Candida, Rhodotorula, Saccharomyces, Geotrichum, Williopsis, Hanseniaspora, Meyerozyma, Torulaspora, Trichosporon, Pichia, Debaryomyces, Lachanceae and Rhodosporidiu ; While the yeast species implicated in plant disease control activities includes Candida tropicals, Candida valida, Candida saitoana, Saccharomyces cerevisiae, Saccharomyces kudriavzevii, Rhodotorula glutinis, Rhodotorula mucilaginosa, Zygosaccharomyces bailli, Aureobasidium sp, Pichia caribaea, Geotrichum candidum, Trichosporon asahii and Eremothecium cymbalariae. The diverse functionality of these yeasts is discussed in this paper.

A special drop: Characterising yeast isolates associated with fermented beverages produced by Australia's indigenous peoples.

Way-a-linah, an alcoholic beverage produced from the fermented sap of Eucalyptus gunnii, and tuba, a fermented drink made from the syrup of Cocos nucifera fructifying bud, are two of several fermented beverages produced by Australian Aboriginal and Torres Strait people. Here we describe the characterisation of yeast isolates from samples associated with the fermentation of way-a-linah and tuba. Microbial isolates were obtained from two different geographical locations in Australia - the Central Plateau in Tasmania, and Erub Island in the Torres Strait. While Hanseniaspora species and Lachancea cidri were the most abundant species in Tasmania, Candida species were the most abundant in Erub Island. Isolates were screened for tolerance to stress conditions found during the production of fermented beverages and for enzyme activities relevant to the appearance, aroma and flavour of these beverages. Based on screening results, eight isolates were evaluated for their volatile profile during the fermentation of wort, apple juice and grape juice. Diverse volatile profiles were observed for beers, ciders and wines fermented with different isolates. These findings reveal the potential of these isolates to produce fermented beverages with unique aroma and flavour profiles and highlight the vast microbial diversity associated with fermented beverages produced by Australia's Indigenous peoples.

A peculiar cell cycle arrest at g2/m stage during the stationary phase of growth in the wine yeast Hanseniaspora vineae.

Yeasts of the genus Hanseniaspora gained notoriety in the last years due to their contribution to wine quality, and their loss of several genes, mainly related to DNA repair and cell cycle processes. Based on genomic data from many members of this genus, they have been classified in two well defined clades: the "faster-evolving linage" (FEL) and the "slower-evolving lineage" (SEL). In this context, we had detected that H. vineae exhibited a rapid loss of cell viability in some conditions during the stationary phase compared to H. uvarum and S. cerevisiae. The present work aimed to evaluate the viability and cell cycle progression of representatives of Hanseniaspora species along their growth in an aerobic and discontinuous system. Cell growth, viability and DNA content were determined by turbidity, Trypan Blue staining, and flow cytometry, respectively. Results showed that H. uvarum and H. opuntiae (representing FEL group), and H. osmophila (SEL group) exhibited a typical G1/G0 (1C DNA) arrest during the stationary phase, as S. cerevisiae. Conversely, the three strains studied here of H. vineae (SEL group) arrested at G2/M stages of cell cycle (2C DNA), and lost viability rapidly when enter the stationary phase. These results showed that H. vineae have a unique cell cycle behavior that will contribute as a new eukaryotic model for future studies of genetic determinants of yeast cell cycle control and progression.

Wine Aroma Characterization of the Two Main Fermentation Yeast Species of the Apiculate Genus Hanseniaspora

Hanseniaspora species are the main yeasts isolated from grapes and grape musts. Regarding genetic and phenotypical characterization, especially fermentative behavior, they can be classified in two technological clusters: the fruit group and the fermentation group. Among the species belonging to the last group, Hanseniaspora osmophila and Hanseniaspora vineae have been previously isolated in spontaneous fermentations of grape must. In this work, the oenological aptitudes of the two species of the fermentation group were compared with Saccharomyces cerevisiae and the main species of the fruit group, Hanseniaspora uvarum. Both H. osmophila and H. vineae conferred a positive aroma to final wines and no sensory defects were detected. Wines fermented with H. vineae presented significantly higher concentrations of 2-phenylethyl, tryptophol and tyrosol acetates, acetoin, mevalonolactone, and benzyl alcohol compared to H. osmophila. Sensorial analysis showed increased intensity of fruity and flowery notes in wines vinificated with H. vineae. In an evolutionary context, the detoxification of alcohols through a highly acetylation capacity might explain an adaption to fermentative environments. It was concluded that, although H. vineae show close alcohol fermentation adaptations to H. osmophila, the increased activation of phenylpropanoid metabolic pathway is a particular characteristic of H. vineae within this important apiculate genus.

Effect of Aeration on Yeast Community Structure and Volatile Composition in Uninoculated Chardonnay Wines

Uninoculated wines are regarded as having improved mouthfeel and texture and more complex flavor profiles when compared to wines inoculated with commercial S. cerevisiae strains. Uninoculated fermentation involves a complex microbial succession of yeasts and bacteria during fermentation. Microbial population dynamics are affected by several factors that can ultimately determine if a particular species or strain contributes to wine aroma and flavor. In this work, we have studied the effect of aeration, a common winemaking practice, on the yeast microbiota during uninoculated Chardonnay wine fermentation. The timing of aeration and then aeration intensity were evaluated across two successive vintages. While the timing of aeration significantly impacted fermentation efficiency across oxygen treatments, different levels of aeration intensity only differed when compared to the non-aerated control ferments. Air addition increased the viable cell population size of yeast from the genera Hanseniaspora, Lachancea, Metschnikowia and Torulaspora in both vintages. While in 2019, a high relative abundance was found for Hanseniaspora species in aerated ferments, in 2020, T. delbrueckii was visibly more abundant than other species in response to aeration. Accompanying the observed differences in yeast community structure, the chemical profile of the finished wines was also different across the various aeration treatments. However, excessive aeration resulted in elevated concentrations of ethyl acetate and acetic acid, which would likely have a detrimental effect on wine quality. This work demonstrates the role of aeration in shaping yeast population dynamics and modulating a volatile profile in uninoculated wines, and highlights the need for careful air addition to avoid a negative sensory impact on wine flavor and aroma.

Genome sequencing, annotation and exploration of the SO2-tolerant non-conventional yeast Saccharomycodes ludwigii

BackgroundSaccharomycodes ludwigii belongs to the poorly characterized Saccharomycodeacea family and is known by its ability to spoil wines, a trait mostly attributable to its high tolerance to sulfur dioxide (SO2). To improve knowledge about Saccharomycodeacea our group determined whole-genome sequences of Hanseniaspora guilliermondii (UTAD222) and S. ludwigii (UTAD17), two members of this family. While in the case of H. guilliermondii the genomic information elucidated crucial aspects concerning the physiology of this species in the context of wine fermentation, the draft sequence obtained for S. ludwigii was distributed by more than 1000 contigs complicating extraction of biologically relevant information. In this work we describe the results obtained upon resequencing of S. ludwigii UTAD17 genome using PacBio as well as the insights gathered from the exploration of the annotation performed over the assembled genome.ResultsResequencing of S. ludwigii UTAD17 genome with PacBio resulted in 20 contigs totaling 13 Mb of assembled DNA and corresponding to 95% of the DNA harbored by this strain. Annotation of the assembled UTAD17 genome predicts 4644 protein-encoding genes. Comparative analysis of the predicted S. ludwigii ORFeome with those encoded by other Saccharomycodeacea led to the identification of 213 proteins only found in this species. Among these were six enzymes required for catabolism of N-acetylglucosamine, four cell wall β-mannosyltransferases, several flocculins and three acetoin reductases. Different from its sister Hanseniaspora species, neoglucogenesis, glyoxylate cycle and thiamine biosynthetic pathways are functional in S. ludwigii. Four efflux pumps similar to the Ssu1 sulfite exporter, as well as robust orthologues for 65% of the S. cerevisiae SO2-tolerance genes, were identified in S. ludwigii genome.ConclusionsThis work provides the first genome-wide picture of a S. ludwigii strain representing a step forward for a better understanding of the physiology and genetics of this species and of the Saccharomycodeacea family. The release of this genomic sequence and of the information extracted from it can contribute to guide the design of better wine preservation strategies to counteract spoilage prompted by S. ludwigii. It will also accelerate the exploration of this species as a cell factory, specially in production of fermented beverages where the use of Non-Saccharomyces species (including spoilage species) is booming.

Comparison of the Glycolytic and Alcoholic Fermentation Pathways of Hanseniaspora vineae with Saccharomyces cerevisiae Wine Yeasts

Hanseniaspora species can be isolated from grapes and grape musts, but after the initiation of spontaneous fermentation, they are displaced by Saccharomyces cerevisiae. Hanseniaspora vineae is particularly valuable since this species improves the flavour of wines and has an increased capacity to ferment relative to other apiculate yeasts. Genomic, transcriptomic, and metabolomic studies in H. vineae have enhanced our understanding of its potential utility within the wine industry. Here, we compared gene sequences of 12 glycolytic and fermentation pathway enzymes from five sequenced Hanseniaspora species and S. cerevisiae with the corresponding enzymes encoded within the two sequenced H. vineae genomes. Increased levels of protein similarity were observed for enzymes of H. vineae and S. cerevisiae, relative to the remaining Hanseniaspora species. Key differences between H. vineae and H. uvarum pyruvate kinase enzymes might explain observed differences in fermentative capacity. Further, the presence of eight putative alcohol dehydrogenases, invertase activity, and sulfite tolerance are distinctive characteristics of H. vineae, compared to other Hanseniaspora species. The definition of two clear technological groups within the Hanseniaspora genus is discussed within the slow and fast evolution concept framework previously discovered in these apiculate yeasts.

Investigations of the mechanisms of interactions between four non-conventional species with Saccharomyces cerevisiae in oenological conditions.

Fermentation by microorganisms is a key step in the production of traditional food products such as bread, cheese, beer and wine. In these fermentative ecosystems, microorganisms interact in various ways, namely competition, predation, commensalism and mutualism. Traditional wine fermentation is a complex microbial process performed by Saccharomyces and non-Saccharomyces (NS) yeast species. To better understand the different interactions occurring within wine fermentation, isolated yeast cultures were compared with mixed co-cultures of one reference strain of S. cerevisiae with one strain of four NS yeast species (Metschnikowia pulcherrima, M. fructicola, Hanseniaspora opuntiae and H. uvarum). In each case, we studied population dynamics, resource consumed and metabolites produced from central carbon metabolism. This phenotyping of competition kinetics allowed us to confirm the main mechanisms of interaction between strains of four NS species. S. cerevisiae competed with H. uvarum and H. opuntiae for resources although both Hanseniaspora species were characterized by a strong mortality either in mono or mixed fermentations. M. pulcherrima and M. fructicola displayed a negative interaction with the S. cerevisiae strain tested, with a decrease in viability in co-culture. Overall, this work highlights the importance of measuring specific cell populations in mixed cultures and their metabolite kinetics to understand yeast-yeast interactions. These results are a first step towards ecological engineering and the rational design of optimal multi-species starter consortia using modeling tools. In particular the originality of this paper is for the first times to highlight the joint-effect of different species population dynamics on glycerol production and also to discuss on the putative role of lipid uptake on the limitation of some non-conventional species growth although interaction processes.

Influence of selected native yeast starter cultures on the antioxidant activities, fermentation index and total soluble solids of Malaysia cocoa beans: A simulation study

Antioxidant activity of cocoa beans is often influenced by drying and roasting stages. In this study, 13 naturally-existing yeast strains were isolated and used as a starter culture and the resulted antioxidant properties of cocoa beans were determined by total polyphenols content (TPC), 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity and total flavonoids content (TFC). The isolated yeasts were identified via sequencing using universal primers ITS 1 and 4. Results revealed that the 13 naturally-existing yeast strains were Pichia kudriavzevii (MH979676, MH979680, MH979681, and MH979677), Hanseniaspora thailandica (MH979675), Hanseniaspora species (MH979678), Wickerhamomyces species (MH979679), Saccharomyces cerevisiae (MH979683), Hanseniaspora opuntiae (MH979684) and Candida quercitrusa (MH979685, MH979687, MH979686 and MH979682). Yeasts were selected based on the phylogenetic analysis, where each species of different genus (except Candida genus) was used as a starter culture. Dried cocoa beans inoculated with isolates (Hanseniaspora thailandica, Pichia kudriavzevii, Hanseniaspora opuntiae, Hanseniaspora species, Wickerhamomyces species and Saccharomyces cerevisiae) contained TPC, TFC and DPPH ranging from 21.82 to 69.81 mg/g Gallic acid (GAE), 1.68–6.33 mg/g Catechin and 113.85 to 328 μmol/g Trolox (TE), respectively. It is noted that there was no significant change of the antioxidant activity between isolates at 24-h to 120-h fermentation. Based on the current study, Hanseniaspora thailandica and Pichia kudriavzevii are the potential starter cultures that result in cocoa beans with higher antioxidant content (p < 0.05) compared to natural fermentation.

Response of Wild Spotted Wing Drosophila (Drosophila suzukii) to Microbial Volatiles.

The olfactory cues used by various animals to detect and identify food items often include volatile organic compounds (VOCs) produced by food-associated microorganisms. Microbial VOCs have potential as lures to trap animal pests, including insect crop pests. This study investigated microorganisms whose VOCs are attractive to natural populations of the spotted wing drosophila (SWD), an invasive insect pest of ripening fruits. The microorganisms readily cultured from wild SWD and SWD-infested fruits included yeasts, especially Hanseniaspora species, and various bacteria, including Proteobacteria (especially Acetobacteraceae and Enterobacteriaceae) and Actinobacteria. Traps in a raspberry planting that were baited with cultures of Hanseniaspora uvarum, H. opuntiae and the commercial lure Scentry trapped relatively high numbers of both SWD and non-target drosophilids. The VOCs associated with these baits were dominated by ethyl acetate and, for yeasts, other esters. By contrast, Gluconobacter species (Acetobacteraceae), whose VOCs were dominated by acetic acid and acetoin and lacked detectable ethyl acetate, trapped 60-75% fewer SWD but with very high selectivity for SWD. VOCs of two other taxa tested, the yeast Pichia sp. and Curtobacterium sp. (Actinobacteria), trapped very few SWD or other insects. Our demonstration of among-microbial variation in VOCs and their attractiveness to SWD and non-pest insects under field conditions provides the basis for improved design of lures for SWD management. Further research is required to establish how different microbial VOC profiles may function as reliable cues of habitat suitability for fly feeding and oviposition, and how this variation maps onto among-insect species differences in habitat preference.

Yeast Species, Strains, and Growth Media Mediate Attraction of Drosophila suzukii (Diptera: Drosophilidae).

Specific ecological interactions between insects and microbes have potential in the development of targeted pest monitoring or control techniques for the spotted wing drosophilid, Drosophila suzukii (Matsumura), an exotic invasive pest of soft fruit. To evaluate D. suzukii attraction to yeast species from preferred types of fruit, three yeasts were isolated from blackberry fruit and two yeasts from raspberry fruit and used to bait simple plastic bottle traps. Saccharomyces cerevisiae and Hanseniaspora uvarum were identified from blackberries, whereas a different H. uvarum strain was identified from raspberry. Yeast identification was based on sequence analysis of the D1/D2 domain of the large subunit 26S rRNA gene. Commercial baker’s yeast (S. cerevisiae) was similar or more effective for the capture of D. suzukii males and females than yeasts isolated from blackberry or raspberry when grown in sucrose. However, when grown in corn syrup, a strain of S. cerevisiae from blackberry captured the highest number of females and a strain of H. uvarum isolated from raspberry captured high numbers of males and females. Species of Candida, Hanseniaspora, and Pichia from a laboratory yeast collection did not outperform baker’s yeast in pairwise tests when grown in sucrose solution or yeast-peptone-dextrose medium. The raspberry strain of H. uvarum grown in corn syrup outperformed S. cerevisiae grown in sucrose, in terms of captures in baited traps under laboratory conditions. We conclude that yeast species, strain, and growth medium can have a marked influence on D. suzukii attraction to baited traps, a finding that could assist in the development of yeast-related monitoring or control techniques targeted at this pest.

Hanseniaspora terricola sp. nov., an ascomycetous yeast isolated from Tibet.

Eight apiculate strains isolated from Tibet, PR China, were identified as Hanseniaspora taiwanica and a novel species of Hanseniaspora based on the sequence analysis of the ITS region, the D1/D2 domains of the LSU rRNA and the translation elongation factor 1-a (TEF1) gene. Among them, four strains with identical sequences of D1/D2 and ITS formed a separate branch from the known Hanseniaspora species in the phylogenetic trees, and differed from the known species by at least 17 (3 %) nucleotide (nt) substitutions in the D1/D2 domains and more than 6 % substitutions and inserts/deletes in the ITS region. The phylogenetic analysis indicated that those four strains represent a novel species of Hanseniaspora, for which the names Hanseniaspora terricola sp. nov. (holotype CGMCC 2.6175T; MycoBank MB 834591) is proposed. The other four strains belonging to H. taiwanica produce spherical, void or fusiform ascospores, which differ from the original description that ascospores are absent.

Yeast species isolated from Texas High Plains vineyards and dynamics during spontaneous fermentations of Tempranillo grapes.

Vineyards and grape musts harbor complex locally specific microbial communities, among which yeast species can be responsible of spontaneous alcoholic fermentation. Although relying on indigenous yeast can be a risk for winemaking, local yeast diversity is associated with complexity and stronger identity of the wine produced, compared to inoculated alcoholic fermentation with commercial yeast strains. In this context, the main yeast species present on grapes, leaves and soils of Tempranillo and Cabernet Sauvignon vineyards in the hot semi-arid climate of the Texas High Plains area were investigated, as well as the presence and dynamics of yeast species during spontaneous fermentations of Tempranillo grapes from the same vineyards. Molecular characterization of yeast species was performed using culture-dependent 5.8S-ITS restriction fragment length polymorphism method and sequencing. Yeast species recovered from grapes, leaves, and soils were mainly dominated by Aureobasidium pullulans, Cryptococcus species, Filobasidium species and Naganishia species, typical members of the vineyard environment. One isolate of potential enological interest, Lachancea thermotolerans, a fermenting yeast with potential in must acidification, was recovered from the vineyard environment. However, spontaneous alcoholic fermentations revealed the presence of fermenting yeast species, including Saccharomyces cerevisiae, Lachancea thermotolerans and Hanseniaspora species. The presence of the three aforementioned species is of extreme interest for winemaking in the Texas High Plains area. Indeed, Saccharomyces cerevisiae is the model for alcoholic fermentation, Hanseniaspora species have been shown to improve palatability of wines, and Lachancea thermotolerans has become of increasing interest due to its potential to acidify musts and palatability. One of the main characteristics of grapes grown in the Texas High Plains area being the lack of acidity, focusing on these three yeast species could promote the development of locally oriented started cultures for the production of wines with a stronger local identity.

Genomic content of a novel yeast species Hanseniaspora gamundiae sp. nov. from fungal stromata (Cyttaria) associated with a unique fermented beverage in Andean Patagonia, Argentina.

A novel yeast species was isolated from the sugar-rich stromata of Cyttaria hariotii collected from two different Nothofagus tree species in the Andean forests of Patagonia, Argentina. Phylogenetic analyses of the concatenated sequence of the rRNA gene sequences and the protein-coding genes for actin and translational elongation factor-1α indicated that the novel species belongs to the genus Hanseniaspora. De novo genome assembly of the strain CRUB 1928T yielded a 10.2-Mbp genome assembly predicted to encode 4452 protein-coding genes. The genome sequence data were compared to the genomes of other Hanseniaspora species using three different methods, an alignment-free distance measure, Kr, and two model-based estimations of DNA-DNA homology values, of which all provided indicative values to delineate species of Hanseniaspora. Given its potential role in a rare indigenous alcoholic beverage in which yeasts ferment sugars extracted from the stromata of Cytarria sp., we searched for the genes that may suggest adaptation of novel Hanseniaspora species to fermenting communities. The SSU1-like gene encoding a sulfite efflux pump, which, among Hanseniaspora, is present only in close relatives to the new species, was detected and analyzed, suggesting that this gene might be one factor that characterizes this novel species. We also discuss several candidate genes that likely underlie the physiological traits used for traditional taxonomic identification. Based on these results, a novel yeast species with the name Hanseniaspora gamundiae sp. nov. is proposed with CRUB 1928T (ex-types: ZIM 2545T = NRRL Y-63793T = PYCC 7262T; MycoBank number MB 824091) as the type strain. Furthermore, we propose the transfer of the Kloeckera species, K. hatyaiensis, K. lindneri and K. taiwanica to the genus Hanseniaspora as Hanseniaspora hatyaiensis comb. nov. (MB 828569), Hanseniaspora lindneri comb. nov. (MB 828566) and Hanseniaspora taiwanica comb. nov. (MB 828567).

Microbiology of high-sugar must fermentation by novel yeasts from the chihuahuan desert.

This work reports important results of aromatic profiles produced by native yeasts isolated from desert-grown wine grapes from the south of Chihuahua, México. These grapes stand very high temperatures during the ripening season, developing high sugar concentration and high pH. Yeast species found in grapes were identified by polymerase chain reaction and sequence analysis of the 5.8S internal transcribed spacer ribosomal RNA region. Aureobasidium namibiae, Sporobolomyces johnsonii, Candida apicola, Hanseniaspora uvarum, Candida thaimueangensis, Hanseniaspora opuntiae were identified. All of them can grow at glucose concentration of 35% (w/v) and 100 ppm of SO2, and produce low volatile acidity (0.2-1.0 g acetic acid/L). Volatile organic compounds analysis showed that C. thaimueangensis and one strain of C. apicola produce high levels of esters, and Hanseniaspora species produces high levels of higher alcohols and carbonyl compounds. The results of this study contribute to the knowledge about yeast communities associated with desert-grown winegrape yeasts.

Genome Sequences of Three Species of Hanseniaspora Isolated from Spontaneous Wine Fermentations.

Members of the genus Hanseniaspora represent a significant proportion of the normal flora of grape berries and play a significant role in wine fermentation. Here, we present genome sequences for three species of Hanseniaspora, H. opuntiae, H. osmophila, and H. uvarum, which were isolated from spontaneous Chardonnay wine fermentation.

Overwintering of Vineyard Yeasts: Survival of Interacting Yeast Communities in Grapes Mummified on Vines.

The conversion of grape must into wine involves the development and succession of yeast populations differing in species composition. The initial population is formed by vineyard strains which are washed into the must from the crushed grapes and then completed with yeasts coming from the cellar environment. As the origin and natural habitat of the vineyard yeasts are not fully understood, this study addresses the possibility, that grape yeasts can be preserved in berries left behind on vines at harvest until the spring of the next year. These berries become mummified during the winter on the vines. To investigate whether yeasts can survive in these overwintering grapes, mummified berries were collected in 16 localities in the Tokaj wine region (Hungary-Slovakia) in early March. The collected berries were rehydrated to recover viable yeasts by plating samples onto agar plates. For the detection of minority species which would not be detected by direct plating, an enrichment step repressing the propagation of alcohol-sensitive yeasts was also included in the process. The morphological, physiological, and molecular analysis identified 13 basidiomycetous and 23 ascomycetous species including fermentative yeasts of wine-making relevance among the 3879 isolates. The presence of viable strains of these species demonstrates that the grapes mummified on the vine can serve as a safe reservoir of yeasts, and may contribute to the maintenance of grape-colonizing yeast populations in the vineyard over years, parallel with other vectors and habitats. All basidiomycetous species were known phylloplane yeasts. Three Hanseniaspora species and pigmented Metschnikowia strains were the most frequent ascomycetes. Other fermentative yeasts of wine-making relevance were detected only in the enrichment cultures. Saccharomyces (S. paradoxus, S. cerevisiae, and S. uvarum) were recovered from 13% of the samples. No Candida zemplinina was found. The isolates with Aureobasidium morphology turned out to belong to Aureobasidium subglaciale, Kabatiella microsticta, or Columnosphaeria fagi. The ascomyceteous isolates grew at high concentrations of sugars with Wickerhamomyces anomalus being the most tolerant species. Complex interactions including antagonism (growth inhibition, contact inhibition, competition for nutrients) and synergism (crossfeeding) among the isolates and with Botrytis cinerea shape the composition of the overwintering communities.

Oenological prefermentation practices strongly impact yeast population dynamics and alcoholic fermentation kinetics in Chardonnay grape must

Yeast species of Hanseniaspora and Candida genus are predominant during the early stages of winemaking, while species of Metschnikowia, Pichia, Zygoascus, Issatchenkia, Torulaspora and other genera are present at lower population levels. The impact of common oenological practices on yeast dynamics during the prefermentative stage and the early stage of alcoholic fermentation (AF) remains elusive. In this work, the effect of four prefermentative oenological practices (clarification degree, temperature, sulphite and starter yeast addition) on yeast dynamics was evaluated in a Chardonnay grape must. The growth curves of four genus or species, namely Saccharomyces spp., Hanseniaspora spp., Candida zemplinina and Torulasporadelbrueckii, were followed by quantitative PCR. The fermentation kinetics were also recorded, as well as the production of acetic acid. Variance analysis allowed determining the effect of each practice and their interaction factors, as well as their relative importance on yeast dynamics and fermentation kinetics.Our experimental design showed that the population dynamics of the four species were differently impacted by the oenological practices, with some species being more sensitive than others to the clarification degree (C. zemplinina), sulphite addition (Saccharomyces spp.), starter yeast inoculation (Hanseniaspora spp.) or prefermentation temperature (T.delbrueckii). Significant interaction effects between practices were revealed, highlighting the interest of experimental design allowing interaction analysis, as some factors may buffer the effect of other ones. Hanseniaspora genus showed atypical behaviour: growth dynamics showed a decrease during AF that we interpreted as early cellular lysis. In conclusion, this study provides new insights on the impact of common oenological practices on the dynamics of non-Saccharomyces yeast that will be useful for a better management of mixed fermentation between S. cerevisiae and non-Saccharomyces yeasts.