Giacomo Zapparoli

Yeasts of the genus Yamadazyma have received increasing attention in the last decade due to the description of new species, their diverse ecological distribution and their biotechnological potential. The genus Yamadazyma was proposed in 1989, but was not accepted until 2005 due to its polyphyletic nature. Over the years, many new species have been described, and several Candida species have been reassigned to Yamadazyma . However, some Yamadazyma species remain unvalidated, and it is unclear whether the genus Keqinozyma is truly a distinct or should be included within Yamadazyma . Currently, the genus Yamadazyma formally includes 72 species. This genus is widely distributed across various environments worldwide, including aquatic habitats, phylloplane, insects, soil, food products, and humans. Although some species and phylogenetic groups exhibit recurring ecological and geographical patterns, such associations are not generally exclusive. Overall, the genus Yamadazyma appears to be ubiquitous. The presence of this genus across various habitats has facilitated studies on its biotechnological applications including cellobiose fermentation for second‐generation bioethanol production and biosynthesis of value‐added metabolites such as riboflavin. The genus Yamadazyma plays an active role in food production, contributing to product quality through enzymatic and antagonistic activities, while in agriculture it shows potential through biocontrol activity against phytopathogens. Recent descriptions of new species and the reclassification of previously classified Candida species have fragmented information on this genus. This review aims to address knowledge gaps regarding Yamadazyma by providing a comprehensive resource that unifies taxonomy, ecology, biotechnology, and pathogenesis to support further studies.

Seven yeast strains, isolated from an alpine peatland, plants and insect frass in Europe (Italy, Russia and Germany), were accommodated in three new species belonging to the subphylum Pucciniomycotina . Phylogenetic analyses based on sequences of the D1/D2 domains of the 26S ribosomal RNA and the internal transcribed spacer (ITS) region placed two novel species closely related to Halobasidium xiangyangense and Halobasidium phyllopilum ( Cystobasidiomycetes ), while a third one was found to be closely related to Sterigmatospora layueensis ( Agaricostilbomycetes ). The tree topology positioned the Halobasidium isolates in two distinct subclades. Physiological characterization showed that the three novel species differed from their closest relatives. Sexual structures were not observed. These new species are primarily associated with the phyllosphere. The species described here are Halobasidium palustre sp. nov. (PYCC 10024 ^T ; MycoBank MB 862292), Halobasidium insectorum sp. nov. (PYCC 10357 ^T ; MycoBank MB 862293) and Sterigmatospora alpina sp. nov. (PYCC 10025 ^T ; MycoBank MB 862295).

Three yeast strains of the basidiomycetous genus Kwoniella (subphylum Agaricomycotina; class Tremellomycetes; subclass Tremellomycetidae) were isolated from samples of olive oil collected in northern Italy. Analysis of the D1/D2 domains of the 26S rRNA gene (LSU) and of the complete internal transcribed spacer (ITS) region indicated that these strains displayed high sequence similarity to three other strains isolated from insect frass in olive trees in South Africa, suggesting that they are conspecific. Phylogenetic analyses based on LSU and ITS sequences placed these six strains in a well-supported clade closely related to Kwoniella newhampshirensis, Kwoniella shandongensis and Kwoniella lonicerae with sequence divergence of 1.2–1.6% (7–9 nucleotide substitutions) in the D1/D2 domains and 1.8–6.4% (12–37 nucleotide substitutions) in the ITS regions. Based on these results and on phenotypic analyses, a novel species, Kwoniella olivae f.a. sp. nov. PYCC 9971^T (=CBS 18666^T), is proposed. The MycoBank number is MB 860006.

Post-harvest losses are estimated to affect, on average, 10% of fresh fruits and vegetables, and can rise to 23% for highly perishable products. This study explores the upcycling of unmarketable cherries (rejected due to size or shape) into low-alcohol sparkling wine. Cherries from local Italian varieties were selected based on ripening stage (early and late). For each ripening group, two widely cultivated varieties were combined in equal proportions to represent the typical compositional profile. Sparkling cherry wines were produced using the Charmat method and analyzed for oenological parameters, polyphenols, proanthocyanidins, polysaccharides, protein content, foam properties, color, and volatile compounds. Wines produced from late-ripening cherries showed significantly higher levels of polyphenols, proteins, and volatile compounds compared to those from early-ripening cherries. These differences resulted in more stable foam and a deeper red coloration. Volatile compound analysis revealed higher concentrations of alcohols, esters, fatty acids, aldehydes, volatile phenols, and terpenes in the late-ripening cherry wines, with volatile phenols particularly elevated. Key differentiating compounds included acetate esters, ethyl esters of fatty acids (e.g., ethyl butyrate, ethyl hexanoate, and ethyl octanoate), and fatty acids (hexadecenoic and octadecanoic acids). These compositional differences are expected to influence the wines’ sensory characteristics. Overall, the findings demonstrate the feasibility of converting second-grade cherries into value-added sparkling wine, offering a sustainable and innovative approach to reducing food waste.

This study analysed basidiomycetous yeasts isolated from the phylloplane of crops and spontaneous plants in Italian agroecosystems. A total of 25 species belonging to 17 genera were recognized by analysing 83 isolates from vineyards and orchards, that are not treated with synthetic fungicides, and adjacent natural areas. Rhodotorula graminis and Filobasidium magnum were the most frequent species but 13 others were represented by a single isolate (e.g., Buckleyzyma salicina, Pseudozyma prolifica, and Moniliella megachiliensis). Preliminary analysis of (GTG)₅-PCR fingerprinting revealed high genetic intraspecific heterogeneity. All isolates were characterized by their production of extracellular hydrolytic enzymes and their sensitivity to six commercial fungicides used in Italy. The isolates displayed great variability in these phenotypic traits, which play an important role in the survival of yeast populations in agroecosystems. Most of them exhibited lipolytic, proteolytic, β-glucosidase and pectinolytic activities, but only three (F. magnum, Kwoniella mangroviensis and Ps. prolifica) also had cellulolytic and amylolytic activity. Most isolates were sensitive to four fungicides, and one R. graminis isolate was resistant to all six. This heterogeneity was not related to the geographical origin of the isolates. The lack of selective factors (i.e. pesticide treatments) in the sampling fields and the presence of adjacent natural areas may have favored the maintenance of an elevated level of strain diversity. This study provides new information on phylloplane basidiomycetous yeasts in agroecosystems and opens the way to further investigations into the impact of agricultural practices on the microbial diversity of these natural habitats.

This study evaluates the fermentation performances of non-Saccharomyces strains in fermenting cherry must from Italian cherries unsuitable for selling and not intended to be consumed fresh, and their effects on the chemical composition of the resulting wine. Fermentation trials in 100 and 500 mL of must were carried out to select 21 strains belonging to 11 non-Saccharomyces species. Cherry wines obtained by six select strains were chemically analyzed for fixed and volatile compounds. Quantitative data were statistically analyzed by agglomerative hierarchical clustering, partial least squared discriminant analysis, and principal component analysis. Wines revealed significant differences in their composition. Lactic acid and phenylethyl acetate levels were very high in wines produced by Lachancea and Hanseniaspora, respectively. Compared to S. cerevisiae wine, non-Saccharomyces wines had a lower content of fatty acid ethyl esters 4-vinyl guaiacol and 4-vinyl phenol. The multivariate analysis discriminated between wines, demonstrating the different contributions of each strain to aroma components. Specifically, all wines from non-Saccharomyces strains were kept strictly separate from the control wine. This study provided comprehensive characterization traits for non-conventional strains that enhance the aroma complexity of cherry-based wine. The use of these yeasts in cherry wine production appears promising. Further investigation is required to ascertain their suitability for larger-scale fermentation.

Film-forming yeasts are potential sources of defects in alcoholic beverages. The aim of this study is to assess the growth capacity of Pichia and Candida film-forming yeasts in cider and wine and the effects on their chemical composition. Cider, partially- and fully-fermented wine were inoculated with strains of C. californica, P. fermentans, P. kluyveri, P. kudriavzevii, P. manshurica and P. membranifaciens to simulate a post-fermentative contamination. The former three species grew only in cider. Pichia manshurica and P. kudriavzevii displayed high viability in wine up to 13.18% (v v^–1) ethanol. Significant changes in odour-active molecules from different chemical groups were observed in cider and wine in the inoculated samples, compared to the non-inoculated ones. cider is more susceptible to contamination by all of the species tested, due to its low alcohol content, while P. membranifaciens, P. manshurica, P. kudriavzevii are additionally potential spoilage agents of wine. This study highlights the risk of cider and wine contamination by film-forming yeasts. Their impact on aroma profiles depends on their ability to grow and their metabolism. This study contributes to an understanding of the possible physiological and metabolic mechanisms responsible for film formation and chemical changes in alcoholic beverages.

This study evaluates the capacity of commercial formulations of synthetic fungicides to inhibit grapevine bacterial growth when sprayed on vineyards to control diseases, such as downy mildew, powdery mildew and secondary rots. Fungicide sensitivity plate assays were carried out on bacteria isolated from vineyards that were also identified and characterized for their plant growth-promoting (PGP) traits and antifungal activity. The high taxonomic variability of bacteria screened with different chemical classes of fungicides is one new finding of this study. Seven out of 11 fungicides were able to inhibit the growth of bacteria at a concentration corresponding to the maximum dose allowed by law in spray treatments of vineyards. Bacterial sensitivity to each fungicide varied greatly. Many sensitive isolates displayed PGP traits and/or antagonistic activity. This study shows the potential impact of fungicidal treatments on grapevine bacterial microbiota. The involvement of bacteria beneficial to the growth and health of plants underlines the importance of this investigation. Our data reveal that the control of a certain disease may be possible using fungicides that have no or low impact on natural non-target microbiota. Understanding the action mechanisms of the active ingredients in these products is a priority for the development of new eco-friendly pesticides.

The characterization of Oenococcus oeni strains isolated from Nero di Troia wine (Apulia, Italy) sampled in two distinct production areas was carried out. The two indigenous populations, consisting of 95 and 97 isolates, displayed high genetic diversity when analyzed by amplified fragments length polymorphisms (AFLP). Based on the UPGMA dendrogram obtained by AFLP analysis, the two populations displayed similar genotypes that grouped in the same clusters with a high level of similarity (>95%). One genotype was found in only one of the two areas. Representative strains of each cluster were analyzed for their enzymatic activities (esterase, β-glucosidase, and protease), assayed in whole cells, and tested for their metabolic properties (consumption of L-malic acid, citric acid, acetaldehyde, and arginine) and growth parameters. Significant differences among strains, including the reference strain ATCC BAA-1163, were observed for all of these properties. Principal component analysis evidenced phenotypic differences among strains, and well separated some of them belonging to different genotypes. Strains exhibiting the best performances in most of these traits could be further investigated in order to select possible candidates as malolactic starters for Nero di Troia wine. This study provided insights on the population structure of O. oeni of a local winemaking area useful to the understanding of the regional diversity of this bacterium, an issue not yet completely resolved

Aims The characterization of grape and apple yeasts was carried out to investigate the ecology of basidiomycetes associated with crop environment and fermenting juice. Methods and Results A total of 15 basidiomycetous strains were analysed for plant‐growth promoting properties, sensitivity to fungicides and features related to their survival in fermenting juice (low pH, SO₂ and ethanol sensitivity). Only one strain displayed 1‐aminocyclopropane‐1‐carboxylate deaminase activity, while other strains were able to produce ammonia and indole‐3‐acetic acid, solubilize calcium phosphate, and display catalase activity and antagonism against Botrytis cinerea. Strains presented great variability in their sensitivity to fungicides. Rhodotorula mucilaginosa Yl26 and Sporobolomyces agrorum PYCC 8108^T, displayed low sensitivity to all fungicides, with high tolerance to SO₂ and ethanol, and were able to survive in fermenting grape and apple juice. Conclusions This study revealed the diversity of basidiomycetous yeasts in the important physiological traits that affect their growth, either in the crop environment or in fermenting juice. Significance and Impact of the Study It has identified the possibility of selective effects of fungicide treatments on basidiomycetous yeasts that could offer benefits for grapevines and apple trees, as well as the survival of strains that are better adapted to fermenting juice and that potentially have a role in the aroma of beverages.