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Pichia and Candida species include biofilm-forming yeasts able to spoil foods and beverages. Strains belonging to 10 Pichia and Candida species isolated from apples, grape musts, and wines were analysed. They were subjected to molecular typing and characterized for their ability to grow and ferment must for cider and wine production, and for their biofilm properties. All strains grew similarly in apple and grape must. Glucose-fermenting strains displayed differentiated fermentation performances. Great variation in SO2 and ethanol sensitivity was observed among the strains. Pichia manshurica strains showed high tolerance to both molecules. Eleven and five surface-spreading biofilm (MAT) phenotypes were identified in solid and liquid media, respectively. Strains produced biofilms with variable thicknesses and widths in culture tubes. Cell adherence and aqueous-hydrocarbon biphasic hydrophobicity assays were carried out. Some Pichia manshurica and P. membranifaciens strains exhibited a high capacity to form a thick biofilm and had high cell adherence and hydrophobicity values. These strains could be more likely to colonize the internal surfaces of tanks. This study evidenced that some Pichia and Candida strains can proliferate during apple and grape must fermentation and may be detrimental the beverage quality, due to their specific biofilm properties., (© The Author(s) 2022. Published by Oxford University Press on behalf of Applied Microbiology International.)

Filamentous fungi are the main pathogens of withered grapes destined for passito wine production. Knowledge of which species inhabit these post-harvest fruits and their pathogenicity is essential in order to develop strategies to control infection, but is still scarce. This study investigated the predominant mycobiota of withered grapes through a cultivation-dependent approach. Strain and species heterogeneity was evidenced on examining isolates collected over three consecutive years. Colony morphology and PCR-restriction fragment length polymorphism (PCR-RFLP) analysis revealed the occurrence of several phenotypes and haplotypes, respectively. Strains were phylogenetically analyzed based on sequence typing of different genes or regions (e.g. calmodulin, β-tubulin and internal transcribed spacer region). Beside the most common necrotrophic-saprophytic species of Penicillium, Aspergillus, Alternaria and Botrytis species responsible for fruit rot, other saprobic species were identified (e.g. Trichoderma atroviride, Sarocladium terricola, Arthrinium arundinis and Diaporthe eres) generally not associated with post-harvest fruit diseases. Species such as Penicillium ubiquetum, Cladosporium pseudocladosporioides, Lichtheimia ramosa, Sarocladium terricola, Diaporthe nobilis, Bipolaris secalis, Paraconiothyrium fuckelii and Galactomyces reessii that had never previously been isolated from grapevine or grape were also identified. Moreover, it was not possible to assign a species to some isolates, while some members of Didymosphaeriaceae and Didymellaceae remained unclassified even at genus level. This study provides insights into the diversity of the epiphytic fungi inhabiting withered grapes and evidences the importance of their identification to understand the causes of fruit diseases. Finally, phylogenetic species delimitation furnished data of interest to fungal taxonomy., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Aims: There is scarce information on the occurrence of several fungi that infect withered grapes to produce passito wine. Isolation and characterization of Neofusicoccum parvum strains and evaluation of their effects on withered grape and wine were carried out., Methods and Results: Nine isolates were phenotypically characterized by colony morphology and genetically discriminated by molecular methods. Two representative strains were identified as N. parvum according to the phylogenetic analysis of internal transcribed spacer (ITS), and a part of translation elongation factor 1-alfa (TEF) and β-tubulin DNA sequences. The pathogenicity of both strains on grape berries varied according to the inoculation and incubation conditions. Under withering conditions, infected berries showed browning and shrivelling and some berries showed pycnidial development on the surface. The infection affected laccase, esterase, β-glucosidase and tannase on grape juice as well as the content of several aroma molecules on resulting wines. Strain-specific effects on wine composition were also observed., Conclusions: Neofusicoccum parvum occurred in withered grapes and was able to infect grapes under withering condition changing the aroma wine., Significance and Impact of the Study: This study reports for the first time the N. parvum isolation in fruit-drying rooms and indicates its important role on postharvest grape infection., (© 2015 The Society for Applied Microbiology.)

The knowledge about wine yeasts remains largely dominated by the extensive studies on Saccharomyces (S.) cerevisiae. Molecular methods, allowing discrimination of both species and strains in winemaking, can profitably be applied for characterization of the microflora occurring in winemaking and for monitoring the fermentation process. Recently, some novel yeast isolates have been described as hybrid between S. cerevisiae and Saccharomyces species, leaving the Saccharomyces strains containing non-Saccharomyces hybrids essentially unexplored. In this study, we have analyzed a yeast strain isolated from "Primitivo" grape (http://www.ispa.cnr.it/index.php?page=collezioni&lang=en accession number 12998) and we found that, in addition to the S. cerevisiae genome, it has acquired genetic material from a non-Saccharomyces species. The study was focused on the analysis of chromosomal and mitochondrial gene sequences (ITS and 26S rRNA, SSU and COXII, ACTIN-1 and TEF), 2D-PAGE mitochondrial proteins, and spore viability. The results allowed us to formulate the hypothesis that in the MSH199 isolate a DNA containing an rDNA sequence from Hanseniaspora vineae, a non-Saccharomyces yeast, was incorporated through homologous recombination in the grape environment where yeast species are propagated. Moreover, physiological characterization showed that the MSH199 isolate possesses high technological quality traits (fermentation performance) and glycerol production, resistance to ethanol, SO₂ and temperature) useful for industrial application., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Aims: Isolation and characterization of indigenous Saccharomyces cerevisiae strains from 12 grape varieties grown in an experimental vineyard of Apulia., Methods and Results: Thirty to 40 colonies from each of the 12 fermentations were obtained at the end stage of spontaneous fermentation. By using morphological and physiological methods and by the PCR analysis of internal transcribed ITS1-5,8S-ITS2, the isolates belonging to Saccharomyces genus were identified. These isolates were further characterized by amplification with S. cerevisiae species- and delta element-specific primers, thus allowing the identification of S. cerevisiae strains selected from each of the 12 fermentations. By means of RFLP analysis of mtDNA, each S. cerevisiae population isolated from a single fermentation appeared to constitute a genetically homogenous group. The comparison of the 12 cultivar-specific mtDNA RFLP patterns, allowed classifying the 12 S. cerevisiae populations into three genetically homogenous groups. The isolated strains fermented vigorously in synthetic and grape juice medium and showed high alcohol and sulphur dioxide (SO(2)) resistance and low hydrogen sulphite (H(2)S) production., Conclusions: The molecular analysis, in conjunction with the traditional morphological and physiological methods, was useful in discriminating at strain level the indigenous population of S. cerevisiae present in a vineyard of Apulia. The dominant S. cerevisiae strains identified in the 12 fermented musts showed potentially important oenological characteristics., Significance and Impact of the Study: The characterization of natural S. cerevisiae strains from several typical Italian grapes grown in a restricted experimental vineyard is an important step towards the preservation and exploitation of yeast biodiversity of Apulia, a relevant wine-producing region. The close relationship between the S. cerevisiae strains from different grapes grown in the same vineyard indicated that the occurrence of native strains is representative of the area rather than of the variety of grapes.