Natural yeast flora of different varieties of grapes used for wine making in India

Knowledge gaps on grape sour rot inferred from a systematic literature review

Sour rot (SR) is one of the major diseases affecting grapevine berries, causing severe yield losses and deterioration of wine quality. SR is caused by an etiologic complex of microorganisms, including yeasts, bacteria, and filamentous fungi. This systematic review focuses on the etiology, epidemiology, and control of SR. A total of 74 papers published between 1986 and 2023 were assessed in this review. Description of disease symptoms was quite consistent across the papers, including oxidation of the grape skin, disaggregation of the internal tissues, and detachment of the rotten berries from the pedicel. The affected bunches are characterized by the smell of acetic acid and ethyl acetate that attracts fruit flies (Drosophila spp.). However, several knowledge gaps and/or inconsistencies were identified with respect to SR etiology, epidemiology, and control. Overall, 146 microorganisms were isolated from the affected berries (44.5% yeasts, 34.3% bacteria, and 21.2% filamentous fungi); however, the selected papers could not definitively clarify which species are primarily involved in the etiology of the disease. A general inconsistency was also observed in the methods used to assess the incidence and severity of SR in vineyards, making inter-study comparisons extremely challenging. Inconsistencies were also found in the methods used for pathogenicity assessment in artificial inoculation studies. Furthermore, gaps were detected in terms of SR epidemiology, with a focus on environmental conditions affecting the disease development. The SR management options are limited, and efficacy trials often result in poor, variable, and inconsistent levels of control, which might be attributed to the lack of knowledge on disease epidemiology. These knowledge gaps and inconsistencies were analyzed in this review to inform future research activities.

Microbiomes Associated With the Surfaces of Northern Argentinian Fruits Show a Wide Species Diversity

The fiber, vitamin, and antioxidant contents of fruits contribute to a balanced human diet. In countries such as Argentina, several tropical fruits are witnessing a high yield in the harvest season, with a resulting surplus. Fruit fermentation using autochthonous starter cultures can provide a solution for food waste. However, limited knowledge exists about the microbiota present on the surfaces of fruits and the preceding flowers. In the present exploratory study, the microbiomes associated with the surfaces of tropical fruits from Northern Argentina, such as white guava, passion fruit and papaya were investigated using a shotgun metagenomic sequencing approach. Hereto, one sample composed of 14 white guava fruits, two samples of passion fruits with each two to three fruits representing the almost ripe and ripe stage of maturity, four samples of papaya with each two to three fruits representing the unripe, almost ripe, and ripe stage of maturity were processed, as well as a sample of closed and a sample of open Japanese medlar flowers. A considerable heterogeneity was found in the composition of the fruits’ surface microbiota at the genus and species level. While bacteria dominated the microbiota of the fruits and flowers, a small number of the metagenomic sequence reads corresponded with yeasts and filamentous fungi. A minimal abundance of bacterial species critical in lactic acid and acetic acid fermentations was found. A considerable fraction of the metagenomic sequence reads from the fruits’ surface microbiomes remained unidentified, which suggested that intrinsic species are to be sequenced or discovered.

Prospection of indigenous yeasts from Uruguayan Tannat vineyards for oenological applications

Prospection of yeasts from oenological environments can provide knowledge of new native strains that are capable of fermenting must and positively influence the composition and sensory characteristics of the wine. This work addressed the biotechnological characterization of indigenous yeasts of Tannat must, an emblematic and widespread vineyard of Uruguay. Fifty-three yeast isolates were morphologically characterized and further identified by amplification and sequencing of ITS and D1-D2 regions, grouping into a total of fifteen species. One isolate of each species was randomly chosen and evaluated for its technological traits. In presence of ethanol (6 to 16% v/v) and sulfur dioxide (40 mg/L), native Saccharomyces cerevisiae 3FS presented the best growth rates and minor lag phase. Regarding non-Saccharomyces strains, Starmerella bacillaris 3MS stood out for its behavior in vinification conditions, more closely related to S. cerevisiae strains. Saccharomyces cerevisiae 3FS, Starmerella bacillaris 3MS, and Saturnispora diversa 1FS conducted a successful fermentation process reaching a final ethanol concentration ≥ 10% v/v and presenting a killer and resistant phenotype, suggesting that they could be used as pure starter cultures, as well as in mixed culture fermentations. This preliminary screening and oenological characterization of indigenous Saccharomyces cerevisiae and non-Saccharomyces yeasts might be a useful tool to identify some strains as potential candidates for wine vinification.

Insights into the ecology of Schizosaccharomyces species in natural and artificial habitats

The fission yeast genus Schizosaccharomyces contains important model organisms for biological research. In particular, S. pombe is a widely used model eukaryote. So far little is known about the natural and artificial habitats of species in this genus. Finding out where S. pombe and other fission yeast species occur and how they live in their habitats can promote better understanding of their biology. Here we investigate in which substrates S. pombe, S. octosporus, S. osmophilus and S. japonicus are present. To this end about 2100 samples consisting of soil, tree sap fluxes, fresh fruit, dried fruit, honey, cacao beans, molasses and other substrates were analyzed. Effective isolation methods that allow efficient isolation of the above mentioned species were developed. Based on the frequency of isolating different fission yeast species in various substrates and on extensive literature survey, conclusions are drawn on their ecology. The results suggest that the primary habitat of S. pombe and S. octosporus is honeybee honey. Both species were also frequently detected on certain dried fruit like raisins, mango or pineapple to which they could be brought by the honey bees during ripening or during drying. While S. pombe was regularly isolated from grape mash and from fermented raw cacao beans S. octosporus was never isolated from fresh fruit. The main habitat of S. osmophilus seems to be solitary bee beebread. It was rarely isolated from raisins. S. japonicus was mainly found in forest substrates although it occurs on fruit and in fruit fermentations, too.

The effect of vine variety and vintage on wine yeast community structure of grapes and ferments

AIMS

The yeast community structure associated with grapes is an essential part of the wine-growing chain with a significant effect on wine quality. The aim of the present study was to evaluate the effect of the varietal factor on the yeast community assembly on grapes and during must fermentation.

METHODS AND RESULTS

We analysed the wine yeast populations associated with four different grape varieties from the Greek national collection vineyard of Lykovryssi. The vintage effect was also considered by sampling the grapes for two consecutive years. Fourteen yeast species were recovered and genotyped to distinct subpopulations. A relatively stable yeast community structure was detected across vintages, with Hanseniaspora guilliermondii being the core species of the vineyard under study. The detected species subpopulations shared a relatively high genetic similarity with several genotypes persisting across vintages.

CONCLUSIONS

It was shown that different grape cultivars were associated with distinct yeast communities, pointing to their possible implication on wine chemical diversity.

SIGNIFICANCE AND IMPACT OF THE STUDY

Present findings show that the varietal factor is an important sharpener of the vineyard-associated wine yeast community, which may interfere with the organoleptic profile of the resulting wines.

Isolation and Characterization of Chitosans from Different Fungi with Special Emphasis on Zygomycetous Dimorphic Fungus Benjaminiella poitrasii: Evaluation of Its Chitosan Nanoparticles for the Inhibition of Human Pathogenic Fungi

The cell wall chitosan was extracted from fungi belonging to different taxonomic classes, namely, Benjaminiella poitrasii (Zygomycetes, dimorphic), Hanseniaspora guilliermondii, Issatchenkia orientalis, Pichia membranifaciens, and Saccharomyces cerevisiae (Ascomycetes, yeasts), and Agaricus bisporus and Pleurotus sajor-caju (Basidiomycetes). The maximum yield of chitosan was 60.89 ± 2.30 mg/g of dry mycelial biomass of B. poitrasii. The degree of deacetylation (DDA) of chitosan extracted from different fungi, as observed with ¹H NMR, was in the range of 70-93%. B. poitrasii chitosan exhibited the highest DDA (92.78%). The characteristic absorption bands were observed at 3450, 1650, 1420, 1320, and 1035 cm^-1 by FTIR. Compared to chitosan from marine sources (molecular weight, MW, 585 kDa), fungal chitosans showed lower MW (6.21-46.33 kDa). Further, to improve the efficacy of B. poitrasii chitosan (Bp), nanoparticles (Np) were synthesized using the ionic gelation method and characterized by dynamic light scattering (DLS). For yeast and hyphal chitosan nanoparticles (BpYCNp and BpHCNp), the average particle size was <200 nm with polydispersity index of 0.341 ± 0.03 and 0.388 ± 0.002, respectively, and the zeta potential values were 21.64 ± 0.34 and 24.48 ± 1.58 mV, respectively. The B. poitrasii chitosans and their nanoparticles were further evaluated for antifungal activity against human pathogenic Candida albicans ATCC 10231, Candida glabrata NCYC 388, Candida tropicalis ATCC 750, Cryptococcus neoformans ATCC 34664, and Aspergillus niger ATCC 10578. BpHCNps showed lower MIC₉₀ values (0.025-0.4 mg/mL) than the chitosan polymer against the tested human pathogens. The study suggested that nanoformulation of fungal chitosan, which has low molecular weight and high % DDA, is desirable for antifungal applications against human pathogens. Moreover, chitosans as well as their nanoparticles were found to be hemocompatible and are therefore safe for healthcare applications.

Diversity of non-Saccharomyces yeasts of grape berry surfaces from representative Cabernet Sauvignon vineyards in Henan Province, China

Non-Saccharomyces yeasts are important players during winemaking and may come from grapes grown in vineyards. To study the diversity of non-Saccharomyces yeasts on surface grape berries, 433 strains were isolated from different Cabernet Sauvignon vineyards grown in Henan Province. Our results demonstrated that these strains were classified into 16 morphotypes according to their growth morphology on Wallerstein Laboratory agar medium, and were identified as seven species from four genera: Hanseniaspora opuntiae, Hanseniaspora vineae, Hanseniaspora uvarum, Pichia occidentalis, Pichia kluyveri, Issatchenkia terricola and Saturnispora diversa based on a series of molecular biological experiments. Hanseniaspora opuntiae was obtained from all sampling sites except Changyuan County, while Pichia kluyveri and Saturnispora diversa were only found in sites of Zhengzhou Grape Resource Garden and Minquan County, respectively. The site Minquan was home of the greatest species richness while only one single species (Hanseniaspora opuntiae) was detected at NAPA winery from Zhengzhou or at Anyang County. Finally, this study suggested that the geographic distribution and diversity of non-Saccharomyces yeast populations on Cabernet Sauvignon grape berries were likely to be determined by a combination of grape varieties and environmental factors.

Sugar-seeking insects as a source of diverse bread-making yeasts with enhanced attributes

Insects represent a particularly interesting habitat in which to search for novel yeasts of value to industry. Insect-associated yeasts have the potential to have traits relevant to modern food and beverage production due to insect-yeast interactions, with such traits including diverse carbohydrate metabolisms, high sugar tolerance, and general stress tolerance. Here, we consider the potential value of insect-associated yeasts in the specific context of baking. We isolated 63 yeast strains from 13 species of hymenoptera from the United States, representing 37 yeast species from 14 genera. Screening for the ability to ferment maltose, a sugar important for bread production, resulted in the identification of 13 strains of Candida, Lachancea, and Pichia species. We assessed their ability to leaven dough. All strains produced baked loaves comparable to a commercial baking strain of Saccharomyces cerevisiae. The same 13 strains were also grown under various sugar and salt conditions relevant to osmotic challenges experienced in the manufacturing processes and the production of sweet dough. We show that many of these yeast strains, most notably strains of Lachancea species, grow at a similar or higher rate and population size as commercial baker's yeast. We additionally assessed the comparative phenotypes and genetics of insect-associated S. cerevisiae strains unable to ferment maltose and identified baking-relevant traits, including variations in the HOG1 signaling pathway and diverse carbohydrate metabolisms. Our results suggest that non-conventional yeasts have high potential for baking and, more generally, showcase the success of bioprospecting in insects for identifying yeasts relevant for industrial uses.

Biogeographical Regionalization of Wine Yeast Communities in Greece and Environmental Drivers of Species Distribution at a Local Scale

Recent research has expanded our understanding on vineyard-associated fungal community assembly, suggesting non-random distribution and implicating regional differences in the wine terroir effect. Here, we focused on the culturable fraction of the fungal community that resides on grapes and determine wine quality, the so-called wine yeast populations. We aimed to analyze local-scale yeast community assemblages and to test whether the hypothesis of biogeographical patterns also applies to wine yeasts in particular. Surveying 34 vineyards across four main viticultural zones in Greece showed significant trends in vineyard-specific patterns. At a local scale, viticultural regions were also linked to distinct yeast community compositions. Importantly, major yeast populations directly related to wine fermentation contributed significantly to the delimitation of regions, highlighting their potential influence on the regionality of wine characteristics. In terms of the microbial terroir influence, yeast communities within an area were temporarily stable, which is critical for the regional character of the wine. Community structure could be explained only partially by environmental features. Maximum temperature, elevation, and net precipitation were the highest correlated variables with the yeast community biogeographic patterns. Finally, we also showed that certain environmental factors may drive the population size of specific yeast populations. The present results indicate that the wine yeast community has a geographical character at local scale, which is an important feature of the microbial terroir concept and thus for the wine industry.

Native yeast and non-yeast fungal communities of Cabernet Sauvignon berries from two Washington State vineyards, and persistence in spontaneous fermentation

To address a knowledge gap about the grape berry mycobiome from Washington State vineyards, next-generation sequencing of the internal transcribed spacer region (ITS1) was used to identify native yeast and fungal species on berries of cultivar 'Cabernet Sauvignon' from two vineyards at veraison and harvest in 2015 and 2016. Four hundred fifty-six different yeast amplicon sequence variants (ASV), representing 184 distinct taxa, and 2467 non-yeast fungal ASV (791 distinct taxa) were identified in this study. A set of 50 recurrent yeast taxa, including Phaeococcomyces, Vishniacozyma and Metschnikowia, were found at both locations and sampling years. These yeast species were monitored from the vineyard into laboratory-scale spontaneous fermentations. Taxa assignable to Metschnikowia and Saccharomyces persisted during fermentation, whereas Curvibasidium, which also has possible impact on biocontrol and wine quality, did not. Sulfite generally reduced yeast diversity and richness, but its effect on the abundance of specific yeasts during fermentation was negligible. Among the 106 recurring non-yeast fungal taxa, Alternaria, Cladosporium and Ulocladium were especially abundant in the vineyard. Vineyard location was the primary factor that accounted for the variation among both communities, followed by year and berry developmental stage. The Washington mycobiomes were compared to those from other parts of the world. Sixteen recurrent yeast species appeared to be unique to Washington State vineyards. This subset also contained a higher proportion of species associated with cold and extreme environments, relative to other localities. Certain yeast and non-yeast fungal species known to suppress diseases or modify wine sensory properties were present in Washington vineyards, and likely have consequences to vineyard health and wine quality.

Evolutionary Divergence in DNA Damage Responses among Fungi

Cell cycle checkpoints and DNA repair pathways contribute to maintaining genome integrity and are thought to be evolutionarily ancient and broadly conserved. For example, in the yeast Saccharomyces cerevisiae and humans, DNA damage induces activation of a checkpoint effector kinase, Rad53p (human homolog Chk2), to promote cell cycle arrest and transcription of DNA repair genes.

Cell cycle checkpoints and DNA repair pathways contribute to maintaining genome integrity and are thought to be evolutionarily ancient and broadly conserved. For example, in the yeast Saccharomyces cerevisiae and humans, DNA damage induces activation of a checkpoint effector kinase, Rad53p (human homolog Chk2), to promote cell cycle arrest and transcription of DNA repair genes. However, recent studies have revealed variation in the DNA damage response networks of some fungi. For example, Shor et al. (mBio 11:e03044-20, 2020, https://doi.org/10.1128/mBio.03044-20) demonstrate that in comparison to S. cerevisiae, the fungal pathogen Candida glabrata has reduced activation of Rad53p in response to DNA damage. Consequently, some downstream targets that contribute to S. cerevisiae genome maintenance, such as DNA polymerases, are transcriptionally downregulated in C. glabrata. Downregulation of genome maintenance genes likely contributes to higher rates of mitotic failure and cell death in C. glabrata. This and other recent findings highlight evolutionary diversity in eukaryotic DNA damage responses.

Capturing yeast associated with grapes and spontaneous fermentations of the Negro Saurí minority variety from an experimental vineyard near León

‘Microbial terroir’ relates to the influence of autochthonous yeasts associated with a grape cultivar on the resultant wine. Geographic region, vineyard site and topography, climate and vintage influence the biodiversity of these microbial communities. Current research focus attempts to correlate their ‘microbial fingerprint’ to the sensorial and chemical characteristics of varietal wines from distinct geographical wine regions. This study focuses on the minor red grape variety, Negro Saurí, which has seen a resurgence in the León Appellation of Origin in Spain as a varietal wine. An experimental vineyard at Melgarajo S.A. (42° 15′ 48.68_N 5° 9′ 56.66_W) was sampled over four consecutive vintages, with autochthonous yeasts being isolated from grapes, must and pilot-scale un-inoculated fermentations, and identified by ITS sequencing. Forty-nine isolates belonging to Metschnikowia pulcherrima, Lachancea thermotolerans, Hanseniaspora uvarum and Torulaspora delbrueckii were isolated from grapes and must, and early stages of fermentation dependent on seasonal variation. Saccharomyces cerevisiae predominated throughout fermentation, as a heterogeneous and dynamic population, with seven major biotypes identified amongst 110 isolates across four consecutive vintages. Twenty-four S. cerevisiae isolates representing five strains dominated in two or more vintages. Their persistence through fermentation warrants further validation of their oenological properties as starter cultures.

Growth Dynamics and Diversity of Yeasts during Spontaneous Plum Mash Fermentation of Different Varieties

The influence of fruit varieties on yeast ecology during spontaneous plum mash fermentation was investigated. Yeast colonies were isolated from mashes obtained from four plum varieties throughout fermentation in laboratory conditions during two consecutive years. The yeast strains were differentiated by random amplification of polymorphic DNA (RAPD-PCR) and identified by the 26S rDNA D1/D2 sequence analysis. Hanseniaspora uvarum, Metschnikowia spp. and Pichia kudriavzevii were the dominant yeasts during the early stages of plum mash fermentation, while the middle and end phases were dominated by Saccharomyces cerevisiae. The strains of Candida sake, Nakazawaea ernobii, Pichia kluyveri, Rhodotorula mucilaginosa and Wickerhamomyces anomalus were also detected in fermenting plum mashes. Metschnikowia sp. M1, H. uvarum H1 and H2 strains were detected in all samples, irrespective of the tested variety and year. Investigation of the impact of individual yeast strains on the production of volatile compounds showed the potential possibility of using them as starter cultures.

Patterns of Genetic Diversity and the Invasion of Commercial Starters in Saccharomyces cerevisiae Vineyard Populations of Santorini Island

Autochthonous Saccharomyces cerevisiae vineyard populations are important components of the grape/wine system. Besides their direct impact on winemaking, they also constitute an untapped reservoir of genotypes with special technological attributes for the wine industry. Research so far on S. cerevisiae populations has focused on spatial distribution on large scales, yet little is known about the genetic variability of populations within viticultural zones and their temporal genotypic variation. Here, S. cerevisiae populations from different vineyards in Santorini, a small Aegean island, were genotyped and their genetic diversity was assessed within and between vineyards during two consecutive years. Despite the relative geographical isolation of the island, a relatively high genetic diversity was uncovered. The vast majority of genotypes were vineyard-specific, while in one of the vintages, significant differences in the genotypic composition of vineyards were detected. Overall, higher differences were detected between vintages rather than among vineyards. Notably, only four genotypes were common for the two vintages, three of which were commercial S. cerevisiae strains, probably "escapees" from wineries. Nevertheless, the populations of the two vintages were not genetically distinct. Present results highlight the magnitude of genetic diversity in natural wine yeast populations on a small spatial scale, yet the invasion of commercial starters may constitute a potential risk for loss of local yeast biodiversity. However, present results show that industrial strains do not necessarily dominate over the natural strains or their high abundance may be temporary.

Extensive loss of cell-cycle and DNA repair genes in an ancient lineage of bipolar budding yeasts

Cell-cycle checkpoints and DNA repair processes protect organisms from potentially lethal mutational damage. Compared to other budding yeasts in the subphylum Saccharomycotina, we noticed that a lineage in the genus Hanseniaspora exhibited very high evolutionary rates, low Guanine-Cytosine (GC) content, small genome sizes, and lower gene numbers. To better understand Hanseniaspora evolution, we analyzed 25 genomes, including 11 newly sequenced, representing 18/21 known species in the genus. Our phylogenomic analyses identify two Hanseniaspora lineages, a faster-evolving lineage (FEL), which began diversifying approximately 87 million years ago (mya), and a slower-evolving lineage (SEL), which began diversifying approximately 54 mya. Remarkably, both lineages lost genes associated with the cell cycle and genome integrity, but these losses were greater in the FEL. E.g., all species lost the cell-cycle regulator WHIskey 5 (WHI5), and the FEL lost components of the spindle checkpoint pathway (e.g., Mitotic Arrest-Deficient 1 [MAD1], Mitotic Arrest-Deficient 2 [MAD2]) and DNA-damage-checkpoint pathway (e.g., Mitosis Entry Checkpoint 3 [MEC3], RADiation sensitive 9 [RAD9]). Similarly, both lineages lost genes involved in DNA repair pathways, including the DNA glycosylase gene 3-MethylAdenine DNA Glycosylase 1 (MAG1), which is part of the base-excision repair pathway, and the DNA photolyase gene PHotoreactivation Repair deficient 1 (PHR1), which is involved in pyrimidine dimer repair. Strikingly, the FEL lost 33 additional genes, including polymerases (i.e., POLymerase 4 [POL4] and POL32) and telomere-associated genes (e.g., Repressor/activator site binding protein-Interacting Factor 1 [RIF1], Replication Factor A 3 [RFA3], Cell Division Cycle 13 [CDC13], Pbp1p Binding Protein [PBP2]). Echoing these losses, molecular evolutionary analyses reveal that, compared to the SEL, the FEL stem lineage underwent a burst of accelerated evolution, which resulted in greater mutational loads, homopolymer instabilities, and higher fractions of mutations associated with the common endogenously damaged base, 8-oxoguanine. We conclude that Hanseniaspora is an ancient lineage that has diversified and thrived, despite lacking many otherwise highly conserved cell-cycle and genome integrity genes and pathways, and may represent a novel, to our knowledge, system for studying cellular life without them.

The Influence of Fungicide Treatments on Mycobiota of Grapes and Its Evolution during Fermentation Evaluated by Metagenomic and Culture-Dependent Methods

The present study evaluated the impact of organic and conventional fungicide treatments compared with untreated samples (no fungicides were used) on the grape berry yeast community of the Montepulciano variety. The yeast dynamics during the spontaneous fermentation using culture-dependent and -independent methods was also evaluated. Results showed a reduction of yeast biodiversity by conventional treatments determining a negative influence on fermenting yeasts in favor of oxidative yeasts such as Aerobasidium pullulans. Starmerella bacillaris was significantly more present in organic samples (detected by next generation sequencing (NGS)), while Hanseniaspopa uvarum was significantly less present in untreated samples (detected by the culture-dependent method). The fermenting yeasts, developed during the spontaneous fermentation, were differently present depending on the fungicide treatments used. Culture-dependent and -independent methods exhibited the same most abundant yeast species during the spontaneous fermentation but a different relative abundance. Differently, the NGS method was able to detect a greater biodiversity (lower abundant species) in comparison with the culture-dependent method. In this regard, the methodologies used gave a different picture of yeast dynamics during the fermentation process. The results indicated that the fungal treatments can influence the yeast community of grapes leading must fermentation and the final composition of wine.

Diversity and enzymatic profiles of indigenous yeasts isolated from three types of palm wines produced in Côte d'Ivoire

AIMS

To investigate the genotypic diversity and enzymatic activity of yeast flora isolated from spontaneous fermenting saps of various palm trees (Borassus aethiopum, Raphia hookeri, Elaeis guineensis) tapped for palm wines.

METHODS AND RESULTS

PCR-restriction fragment length polymorphism of ITS-5.8S rDNA combined to 26S rRNA gene and/or the partial ACT1 gene sequencing were applied for yeast characterization, and their enzymatic profiles assessed by using API ZYM kits. Thirteen genera and 23 species were identified, with the highest diversity (14 species) in raffia wine. Saccharomyces cerevisiae was dominant and common to all palm wines. Some potentially pathogenic yeasts were also isolated. The majority of tested strains displayed high amylo-peptidase, phosphatase, β-glucosidase and α-glucosidase activities and esterase activity.

CONCLUSIONS

Diverse yeast species colonized palm wines, among which some were related to a specific type of wine and the majority of them have the ability to digest starch, sugar, protein or lipid.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is a first step in understanding the significance of indigenous yeast flora of palm wines from Côte d'Ivoire. This knowledge is important as a tool for establishing new indigenous yeast collection; which could be used for the product quality improvement and as enzyme sources for biotechnological purposes.

Challenges of the Non-Conventional Yeast Wickerhamomyces anomalus in Winemaking

Nowadays it is widely accepted that non-Saccharomyces yeasts, which prevail during the early stages of alcoholic fermentation, contribute significantly to the character and quality of the final wine. Among these yeasts, Wickerhamomyces anomalus (formerly Pichia anomala, Hansenula anomala, Candida pelliculosa) has gained considerable importance for the wine industry since it exhibits interesting and potentially exploitable physiological and metabolic characteristics, although its growth along fermentation can still be seen as an uncontrollable risk. This species is widespread in nature and has been isolated from different environments including grapes and wines. Its use together with Saccharomyces cerevisiae in mixed culture fermentations has been proposed to increase wine particular characteristics. Here, we review the ability of W. anomalus to produce enzymes and metabolites of oenological relevance and we discuss its potential as a biocontrol agent in winemaking. Finally, biotechnological applications of W. anomalus beyond wine fermentation are briefly described.

Genetic variability and physiological traits of Saccharomyces cerevisiae strains isolated from "Vale dos Vinhedos" vineyards reflect agricultural practices and history of this Brazilian wet subtropical area

Vale dos Vinhedos appellation of origin has a very recent history as industrial wine making region. In this study we investigated the genetic and phenotypic variability of Saccharomyces cerevisiae strains isolated from South-Brazilian vineyards in order to evaluate strain fermentation aptitude and copper and sulphites tolerance. Merlot grape bunches were collected from three vineyards and yeast isolation was performed after single bunch fermentation. High genotypic variability was found and most of the genotypes revealed to be vine-specific. No industrial strain dissemination was present in the sampled vineyards, although it has been wildly reported in traditional winemaking countries. From the phenotypic traits analysis these Brazilian native strains showed good fermentation performances, good tolerance to sulphites and, in particular, a high copper tolerance level. Copper is the most important metal in the formulation of fungicides against downy mildew (Plasmopara viticola), one of the most harmful disease of the vines, and other fungal pests. The high tolerance to copper suggests an environmental adaptation to the strong use of copper-based fungicides, requested by the wet subtropical climate.

MALDI-TOF MS Supplementary database for species identification employing the yeast diversity encountered on southern Brazil grapes

The study of grape microflora is of interest when autochthonous yeasts, which are related to typical wine characteristics, are intended to be used in winemaking. The election of matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) as the first method for yeast identification was based on its accuracy and rapidity compared to alternative laboratory protocols for identification. The aims of this study are to consolidate the MALDI-TOF MS Supplementary database for environmental yeasts already constructed, to expand it through the addition of standard spectra of not included yeast species, and to discuss the grape microflora encountered in Southern Brazil. A total of 358 strains, isolated from grape berries, were submitted to protein profiling employing Biotyper and Supplementary database. Molecular biology techniques were used as alternatives to identify 6.4% of strains not promptly designated by protein profiling. These strains corresponded to the species Candida californica, Zygoascus meyerae, Candida akabanensis, Candida azyma, and Hanseniaspora vineae. The MALDI-TOF MS spectra of the identified species were added to Supplementary database. The presented results strengthen the need for further expansion of the mass spectra database to broaden its microbiological application.

Can fungi compete with marine sources for chitosan production?

Chitosan, a β-1,4-linked glucosamine polymer is formed by deacetylation of chitin. It has a wide range of applications from agriculture to human health care products. Chitosan is commercially produced from shellfish, shrimp waste, crab and lobster processing using strong alkalis at high temperatures for long time periods. The production of chitin and chitosan from fungal sources has gained increased attention in recent years due to potential advantages in terms of homogenous polymer length, high degree of deacetylation and solubility over the current marine source. Zygomycetous fungi such as Absidia coerulea, Benjaminiella poitrasii, Cunninghamella elegans, Gongrenella butleri, Mucor rouxii, Mucor racemosus and Rhizopus oryzae have been studied extensively. Isolation of chitosan are reported from few edible basidiomycetous fungi like Agaricus bisporus, Lentinula edodes and Pleurotus sajor-caju. Other organisms from mycotech industries explored for chitosan production are Aspergillus niger, Penicillium chrysogenum, Saccharomyces cerevisiae and other wine yeasts. Number of aspects such as value addition to the existing applications of fungi, utilization of waste from agriculture sector, and issues and challenges for the production of fungal chitosan to compete with existing sources, metabolic engineering and novel applications have been discussed to adjudge the potential of fungal sources for commercial chitosan production.

Association between Grape Yeast Communities and the Vineyard Ecosystems

The grape yeast biota from several wine-producing areas, with distinct soil types and grapevine training systems, was assessed on five islands of Azores Archipelago, and differences in yeast communities composition associated with the geographic origin of the grapes were explored. Fifty-seven grape samples belonging to the Vitis vinifera grapevine cultivars Verdelho dos Açores (Verdelho), Arinto da Terceira (Arinto) and Terrantez do Pico (Terrantez) were collected in two consecutive years and 40 spontaneous fermentations were achieved. A total of 1710 yeast isolates were obtained from freshly crushed grapes and 1200 from final stage of fermentations. Twenty-eight species were identified, Hanseniaspura uvarum, Pichia terricola and Metschnikowia pulcherrima being the three most representative species isolated. Candida carpophila was encountered for the first time as an inhabitant of grape or wine-associated environments. In both sampling years, a higher proportion of H. uvarum in fresh grapes from Verdelho cultivar was observed, in comparison with Arinto cultivar. Qualitatively significant differences were found among yeast communities from several locations on five islands of the Archipelago, particularly in locations with distinctive agro-ecological compositions. Our results are in agreement with the statement that grape-associated microbial biogeography is non-randomly associated with interactions of climate, soil, cultivar, and vine training systems in vineyard ecosystems. Our observations strongly support a possible linkage between grape yeast and wine typicality, reinforcing the statement that different viticultural terroirs harbor distinctive yeast biota, in particular in vineyards with very distinctive environmental conditions.

Yeast Biodiversity in Vineyard Environments Is Increased by Human Intervention

One hundred and five grape samples were collected during two consecutive years from 33 locations on seven oceanic islands of the Azores Archipelago. Grape samples were obtained from vineyards that were either abandoned or under regular cultivation involving common viticultural interventions, to evaluate the impact of regular human intervention on grape yeast biota diversity in vineyards. A total of 3150 yeast isolates were obtained and 23 yeast species were identified. The predominant species were Hanseniaspora uvarum, Pichia terricola, Starmerella bacillaris and Issatchenkia hanoiensis. The species Barnettozyma californica, Candida azymoides and Pichia cecembensis were reported in grapes or wine-associated environments for the first time. A higher biodiversity was found in active vineyards where regular human intervention takes place (Shannon index: 1.89 and 1.53 in the first and second years, respectively) when compared to the abandoned ones (Shannon index: 0.76 and 0.31). This finding goes against the assumptions that human intervention can destroy biodiversity and lead to homogeneity in the environment. Biodiversity indices were considerably lower in the year with the heaviest rainfall. This study is the first to report on the grape yeast communities from several abandoned vineyards that have undergone no human intervention.

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.

Bacaba beverage produced by Umutina Brazilian Amerindians: Microbiological and chemical characterization

Bacaba chicha is a beverage prepared by the indigenous Umutina people from the bacaba fruit (Oenocarpus bacaba), a purple berry that is rich in fat and carbohydrates, as well as a source of phenolic compounds. In this study, samples of bacaba chicha beverage were collected, and the microbial community was assessed using culture-dependent and -independent techniques. The nutritional composition and metabolite profiles were analyzed, and species belonging to lactic acid bacteria (LAB) and yeasts were detected. The LAB group detected by culture-dependent analysis included Enterococcus hormaechei and Leuconostoc lactis. Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) detected additional Propionibacterium avidum, Acetobacter spp., and uncultured bacteria. Pichia caribbica and Pichia guilliermondii were detected in a culture-dependent method, and Pichia caribbica was confirmed by PCR-DGGE analysis. The pH value of the beverage was 6.2. The nutritional composition was as follows: 16.47 ± 0.73 g 100 mL-1 dry matter, 2.2 ± 0.0 g 100 mL-1 fat, 3.36 ± 0.44 g 100 mL-1 protein, and 10.87 ± 0.26 g 100 mL-1 carbohydrate. The metabolites detected were 2.69 g L-1 succinic acid, 0.9 g L-1 acetic acid, 0.49 g L-1 citric acid, 0.52 g L-1 ethanol, and 0.4 g L-1 glycerol. This is the first study to identify microbial diversity in bacaba chicha spontaneous fermentation. This study is also the starting step in the immaterial record of this Brazilian indigenous beverage prepared from bacaba fruit.

FT-IR spectroscopy: A powerful tool for studying the inter- and intraspecific biodiversity of cultivable non-Saccharomyces yeasts isolated from grape must

The efficiency of the FT-IR technique for studying the inter- and intra biodiversity of cultivable non-Saccharomyces yeasts (NS) present in different must samples was examined. In first, the capacity of the technique FT-IR to study the global diversity of a given sample was compared to the pyrosequencing method, used as a reference technique. Seven different genera (Aureobasidium, Candida, Cryptococcus, Hanseniaspora, Issatchenkia, Metschnikowia and Pichia) were identified by FT-IR and also by pyrosequencing. Thirty-eight other genera were identified by pyrosequencing, but together they represented less than 6% of the average total population of 6 musts. Among the species identified, some of them present organoleptic potentials in winemaking, particularly Starmerella bacillaris (synonym Candidazemplinina). So in a second time, we evaluated the capacity of the FT-IR technique to discriminate the isolates of this species because few techniques were able to study intraspecific NS yeast biodiversity. The results obtained were validated by using a classic method as ITS sequencing. Biodiversity at strain level was high: 19 different strains were identified from 58 isolates. So, FT-IR spectroscopy seems to be an accurate and reliable method for identifying major genera present in the musts. The two biggest advantages of the FT-IR are the capacity to characterize intraspecific biodiversity of non-Saccharomyces yeasts and the possibility to discriminate a lot of strains.

Microbes Promote Amino Acid Harvest to Rescue Undernutrition in Drosophila

Microbes play an important role in the pathogenesis of nutritional disorders such as protein-specific malnutrition. However, the precise contribution of microbes to host energy balance during undernutrition is unclear. Here, we show that Issatchenkia orientalis, a fungal microbe isolated from field-caught Drosophila melanogaster, promotes amino acid harvest to rescue the lifespan of undernourished flies. Using radioisotope-labeled dietary components (amino acids, nucleotides, and sucrose) to quantify nutrient transfer from food to microbe to fly, we demonstrate that I. orientalis extracts amino acids directly from nutrient-poor diets and increases protein flux to the fly. This microbial association restores body mass, protein, glycerol, and ATP levels and phenocopies the metabolic profile of adequately fed flies. Our study uncovers amino acid harvest as a fundamental mechanism linking microbial and host metabolism, and highlights Drosophila as a platform for quantitative studies of host-microbe relationships.

Phenotypic and molecular diversity of Meyerozyma guilliermondii strains isolated from food and other environmental niches, hints for an incipient speciation

Meyerozyma guilliermondii is a yeast species widely isolated from several natural environments and from fruit; in medical microbiology it is known as the teleomorph of the opportunistic pathogen Candida guilliermondii, which causes about 2% of the human blood infections. This yeast is also promising in a variety of biotechnological applications as vitamins production and post-harvest control. The question if isolates from different sources are physiologically and genetically similar, or if the various environments induced significant differences, is crucial for the understanding of this species structure and to select strains appropriate for each application. This question was addressed using LSU and ITS sequencing for taxonomic assignment, i-SSR (GACA4) for the molecular characterization and FTIR for the metabolomic fingerprint. All data showed that fruit and environmental isolates cluster separately with a general good agreement between metabolomics and molecular analysis. An additional RAPD analysis was able to discriminate strains according to the isolation position within the pineapple fruit. Although all strains are members of the M. guilliermondii species according to the current standards, the distribution of large variability detected suggests that some specialization occurred in the niches inhabited by this yeast and that food related strains can be differentiated from the medical isolates.

Three clustered cases of candidemia caused by Candida quercitrusa and mycological characteristics of this novel species

We investigated three nosocomial Candida quercitrusa candidemia cases occurring within 2 months in a Chinese hospital. Isolates were identifiable only by DNA sequencing of the rRNA genes. Genetic (via random amplified polymorphic DNA [RAPD]) and protein mass spectral (via matrix-assisted laser desorption ionization-time of flight mass spectrometry [MALDI-TOF MS]) analyses yielded identical profiles suggesting an outbreak. The fluconazole MICs of all the strains were 16 to 32 μg/ml.

Biogeographical characterization of Saccharomyces cerevisiae wine yeast by molecular methods

Biogeography is the descriptive and explanatory study of spatial patterns and processes involved in the distribution of biodiversity. Without biogeography, it would be difficult to study the diversity of microorganisms because there would be no way to visualize patterns in variation. Saccharomyces cerevisiae, "the wine yeast," is the most important species involved in alcoholic fermentation, and in vineyard ecosystems, it follows the principle of "everything is everywhere." Agricultural practices such as farming (organic versus conventional) and floor management systems have selected different populations within this species that are phylogenetically distinct. In fact, recent ecological and geographic studies highlighted that unique strains are associated with particular grape varieties in specific geographical locations. These studies also highlighted that significant diversity and regional character, or 'terroir,' have been introduced into the winemaking process via this association. This diversity of wild strains preserves typicity, the high quality, and the unique flavor of wines. Recently, different molecular methods were developed to study population dynamics of S. cerevisiae strains in both vineyards and wineries. In this review, we will provide an update on the current molecular methods used to reveal the geographical distribution of S. cerevisiae wine yeast.

Grape berry yeast communities: influence of fungicide treatments

The yeast communities colonising grape berry surfaces were evaluated for the influence of fungicide treatments in an organic vineyard (copper/sulphur-based products) and a conventional vineyard (commonly used fungicides). Analysis of yeast abundance and diversity was carried out on grape berries and juice during fermentation, using culture-dependent and -independent approaches. Yeast abundance was as generally reported for mature grapes and it was slight higher from grapes treated with conventional fungicides. Initial grape samples showed less yeast species diversity in the organic vineyard compared with the conventional one. In both vineyards, the dominant yeast were Candida zemplinina and Hanseniaspora uvarum (>50%), respectively, typical species that colonise surfaces of mature grape berries. Metschnikowia pulcherrima was widely found in the conventional samples while it was only occasionally found in organic ones. Saccharomyces cerevisiae was isolated only at the end of natural fermentation (conducted in sterile condition), with lower levels in the organic samples. S. cerevisiae strains showed less intraspecies diversity in the organic samples (two genotypes), in comparison with the conventional samples (six genotypes).

Genetic diversity and population structure of Saccharomyces cerevisiae strains isolated from different grape varieties and winemaking regions

We herein evaluate intraspecific genetic diversity of fermentative vineyard-associated S. cerevisiae strains and evaluate relationships between grape varieties and geographical location on populational structures. From the musts obtained from 288 grape samples, collected from two wine regions (16 vineyards, nine grape varieties), 94 spontaneous fermentations were concluded and 2820 yeast isolates were obtained that belonged mainly (92%) to the species S. cerevisiae. Isolates were classified in 321 strains by the use of ten microsatellite markers. A high strain diversity (8-43 strains per fermentation) was associated with high percentage (60-100%) of fermenting samples per vineyard, whereas a lower percentage of spontaneous fermentations (0-40%) corresponded to a rather low strain diversity (1-10 strains per fermentation).For the majority of the populations, observed heterozygosity (Ho) was about two to five times lower than the expected heterozygosity (He). The inferred ancestry showed a very high degree of admixture and divergence was observed between both grape variety and geographical region. Analysis of molecular variance showed that 81-93% of the total genetic variation existed within populations, while significant differentiation within the groups could be detected. Results from AMOVA analysis and clustering of allelic frequencies agree in the distinction of genetically more dispersed populations from the larger wine region compared to the less extended region. Our data show that grape variety is a driver of populational structures, because vineyards with distinct varieties harbor genetically more differentiated S. cerevisiae populations. Conversely, S. cerevisiae strains from vineyards in close proximity (5-10 km) that contain the same grape variety tend to be less divergent. Populational similarities did not correlate with the distance between vineyards of the two wine regions. Globally, our results show that populations of S. cerevisiae in vineyards may occur locally due to multi-factorial influences, one of them being the grape variety.

Beyond bacteria: a study of the enteric microbial consortium in extremely low birth weight infants

Extremely low birth weight (ELBW) infants have high morbidity and mortality, frequently due to invasive infections from bacteria, fungi, and viruses. The microbial communities present in the gastrointestinal tracts of preterm infants may serve as a reservoir for invasive organisms and remain poorly characterized. We used deep pyrosequencing to examine the gut-associated microbiome of 11 ELBW infants in the first postnatal month, with a first time determination of the eukaryote microbiota such as fungi and nematodes, including bacteria and viruses that have not been previously described. Among the fungi observed, Candida sp. and Clavispora sp. dominated the sequences, but a range of environmental molds were also observed. Surprisingly, seventy-one percent of the infant fecal samples tested contained ribosomal sequences corresponding to the parasitic organism Trichinella. Ribosomal DNA sequences for the roundworm symbiont Xenorhabdus accompanied these sequences in the infant with the greatest proportion of Trichinella sequences. When examining ribosomal DNA sequences in aggregate, Enterobacteriales, Pseudomonas, Staphylococcus, and Enterococcus were the most abundant bacterial taxa in a low diversity bacterial community (mean Shannon-Weaver Index of 1.02±0.69), with relatively little change within individual infants through time. To supplement the ribosomal sequence data, shotgun sequencing was performed on DNA from multiple displacement amplification (MDA) of total fecal genomic DNA from two infants. In addition to the organisms mentioned previously, the metagenome also revealed sequences for gram positive and gram negative bacteriophages, as well as human adenovirus C. Together, these data reveal surprising eukaryotic and viral microbial diversity in ELBW enteric microbiota dominated bytypes of bacteria known to cause invasive disease in these infants.

The microbial ecology of wine grape berries

Grapes have a complex microbial ecology including filamentous fungi, yeasts and bacteria with different physiological characteristics and effects upon wine production. Some species are only found in grapes, such as parasitic fungi and environmental bacteria, while others have the ability to survive and grow in wines, constituting the wine microbial consortium. This consortium covers yeast species, lactic acid bacteria and acetic acid bacteria. The proportion of these microorganisms depends on the grape ripening stage and on the availability of nutrients. Grape berries are susceptible to fungal parasites until véraison after which the microbiota of truly intact berries is similar to that of plant leaves, which is dominated by basidiomycetous yeasts (e.g. Cryptococcus spp., Rhodotorula spp. Sporobolomyces spp.) and the yeast-like fungus Aureobasidium pullulans. The cuticle of visually intact berries may bear microfissures and softens with ripening, increasing nutrient availability and explaining the possible dominance by the oxidative or weakly fermentative ascomycetous populations (e.g. Candida spp., Hanseniaspora spp., Metschnikowia spp., Pichia spp.) approaching harvest time. When grape skin is clearly damaged, the availability of high sugar concentrations on the berry surface favours the increase of ascomycetes with higher fermentative activity like Pichia spp. and Zygoascus hellenicus, including dangerous wine spoilage yeasts (e.g. Zygosaccharomyces spp., Torulaspora spp.), and of acetic acid bacteria (e.g. Gluconobacter spp., Acetobacter spp.). The sugar fermenting species Saccharomyces cerevisiae is rarely found on unblemished berries, being favoured by grape damage. Lactic acid bacteria are minor partners of grape microbiota and while being the typical agent of malolactic fermentation, Oenococcus oeni has been seldom isolated from grapes in the vineyard. Environmental ubiquitous bacteria of the genus Enterobacter spp., Enterococcus spp., Bacillus spp., Burkholderia spp., Serratia spp., Staphylococcus spp., among others, have been isolated from grapes but do not have the ability to grow in wines. Saprophytic moulds, like Botrytis cinerea, causing grey rot, or Aspergillus spp., possibly producing ochratoxin, are only active in the vineyard, although their metabolites may affect wine quality during grape processing. The impact of damaged grapes in yeast ecology has been underestimated mostly because of inaccurate grape sampling. Injured berries hidden in apparently sound bunches explain the recovery of a higher number of species when whole bunches are picked. Grape health status is the main factor affecting the microbial ecology of grapes, increasing both microbial numbers and species diversity. Therefore, the influence of abiotic (e.g. climate, rain, hail), biotic (e.g. insects, birds, phytopathogenic and saprophytic moulds) and viticultural (e.g. fungicides) factors is dependent on their primary damaging effect.

The grape must non-Saccharomyces microbial community: impact on volatile thiol release

Several studies have reported the beneficial influence of non-Saccharomyces yeasts and their potential applications in the wine industry, mainly in mixed-culture fermentation with S. cerevisiae. The potential impact of 15 non-Saccharomyces strains from 7 species on 4-methyl-4-sulfanylpentan-2-one (4MSP) and 3-sulfanylhexan-1-ol (3SH) release in model medium and Sauvignon Blanc must was evaluated after partial fermentation. Whereas the impact of non-Saccharomyces on 4MSP release in both media was low, some M. pulcherrima, T. delbrueckii and K. thermotolerans strains had a high capacity to release 3SH, despite their minimal fermentation activity. As previously demonstrated for Saccharomyces yeast, this contribution is strain dependant. Taking into account their dynamic and quantitative presence during the whole process, the real impact of non-Saccharomyces yeast on 4MSP and 3SH release was evaluated using a recreated community simulating the yeast ecosystem. Our results revealed a positive impact on 3SH release in Sauvignon Blanc wines by promoting non-Saccharomyces yeast activity and delaying the growth of S. cerevisiae. Some non-Saccharomyces yeast strains are capable of making a positive contribution to volatile thiol release in wines, essentially during the pre-fermentation stage in winemaking, when this microbiological sub-population is dominant.

PCR ITS-RFLP: A useful method for identifying filamentous fungi isolates on grapes

Restriction digestion analysis of the ITS products was tested as an easy method to identify isolates of filamentous fungi on grapes. Endonucleases SduI, HinfI, MseI, HaeIII were used. Endonucleases BfmI, Cfr9I, Hpy188I, MaeII or PspGI were used as necessary to complete discrimination. The 43 species studied generated 42 different composite profiles. Only the species P. thomii and P. glabrum gave the same composite profile. 96.3% strains tested could be differentiated to the species level with only four enzymes. Hundred ninety nine strains of filamentous fungi were isolated from various vineyards in Burgundy and identified by this method. Penicillium (58.5%) was the genus the most frequently isolated and no strains of the genus Aspergillus was isolated. P. spinolusum was the most isolated species of Penicillium (22.70%). The species C. cladiosporioides, B. cinerea, E. nigrum, A. alternata, T. koningiopsis, P. diplodiella, C. herbarum, A. alternatum, T. cucumeris and F. oxysporum were also isolated. This technique is a rapid and reliable method appropriate for routine identification of filamentous fungi. This can be used to screen large numbers of isolates from various environments in a short time. This is the first exhaustive study of fungal diversity at species level in vineyard.

Production of volatile phenols by Pichia manshurica and Pichia membranifaciens isolated from spoiled wines and cellar environment in Patagonia

In order to detect spoilage yeast species in wines showing off-odors, different yeast isolation protocols were evaluated. Independently of the isolation method, only Saccharomyces cerevisiae and Pichia manshurica were detected. The spoilage capacity of P. manshurica regional isolates was evaluated in red wine and the production of volatile phenols was evidenced. To evaluate the possible source of contamination, yeasts from both grapes and cellar surfaces were obtained. Hanseniaspora uvarum and Zygoascus hellenicus were detected in both sound and damaged grapes from sunny areas. The most frequent species in cellar surfaces was Candida boidinii, Pichia membranifaciens and P. manshurica were detected in filters. The intra-specific genetic characterization of the P. manshurica isolates by mtDNA-RFLP demonstrated that the same strain was detected in both wine and filter. Most P. membranifaciens isolates produced 4-EP (maximum level of 1.895 mg/L) and particularly high levels of 4-EG (maximum level of 10.260 mg/L) were produced by P. manshurica isolates in synthetic wine-like medium. In this work the capacity of P. manshurica and P. membranifaciens species to produce volatile phenols was shown for the first time.

Yeast species associated with wine grapes in China

Having more information on the yeast ecology of grapes is important for wine-makers to produce wine with high quality and typical attributes. China is a significant wine-consuming country and is becoming a serious wine-producer, but little has been reported about the yeast ecology of local ecosystems. This study provides the first step towards the exploitation of the yeast wealth in China's vine-growing regions. The aim of this study was to investigate the yeast population density and diversity on three grape varieties cultivated in four representative vine-growing regions of China. Yeast species diversity was evaluated by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequence analysis of the 5.8S internal transcribed spacer (ITS) ribosomal DNA (rDNA) region of cultivable yeasts. The grapes harbored yeast populations at 10(2)-10(6)CFU/mL, consisting mostly of non-Saccharomyces species. Seventeen different yeast species belonging to eight genera were detected on the grape samples tested, including Hanseniaspora uvarum, Cryptococcus flavescens, Pichia fermentans, Candida zemplinina, Cryptococcus carnescens, Candida inconpicua, Zygosaccharomyces fermentati, Issatchenkia terricola, Candida quercitrusa, Hanseniaspora guilliermondii, Candida bombi, Zygosaccharomyces bailii, Sporidiobolus pararoseus, Cryptococcus magnus, Metschnikowia pulcherrima, Issatchenkia orientalis and Pichia guilliermondii. H. uvarum and C. flavescens were the dominant species present on the grapes. For the first time Sporidiobolus pararoseus was discovered as an inhabitant of the grape ecosystem. The yeast community on grape berries was influenced by the grape chemical composition, vine-variety and vine-growing region. This study is the first to identify the yeast communities associated with grapes in China using molecular methods. The results enrich our knowledge of wine-related microorganisms, and can be used to promote the development of the local wine industry.