Yeast Identification During Fermentation of Turkish Gemlik Olives.

Naturally fermented black table olives of the Gemlik variety are one of the most consumed fermented products in Turkey. The objective of this work was to identify yeast strains isolated during their natural fermentation by using Restriction Fragments Lengths Polymorphism-Polimerase Chain Reaction (RFLP-PCR) and DNA sequencing methods. The study also focused on determining the effect of regional differences on yeast microflora of naturally fermented Gemlik olives. A total of 47 yeast strains belonging to 12 different species which had been previously isolated from the natural brine of Akhisar and Iznik-Gemlik cv. olives were characterized by molecular methods. Forty-two of the tested strains could be identified by RFLP-PCR to species level. These yeast species were determined as Candida mycetangi, Candida hellenica, Candida membranaefaciens, Candida famata, Candida pelliculosa, Saccharomyces cerevisiae, and Zygosaccharomyces mrakii. Five strains were identified by DNA sequencing. These strains belonged to three different species: Aureobasidium pullulans, Kloeckera apiculate, and Cryptococcus saitoi. The most frequent species were C. famata and C. pelliculosa in both regions. PRACTICAL APPLICATION: This work studies the yeasts from Turkish table olives which could prove to be of importance to the food industry in that area. On the other hand, it compares identification by molecular and classical biochemical methods and offers an idea about the differences between the ecosystems of Gemlik olives in the Akhisar (AO) and Iznik (IO) regions. The study could be useful in characterizing a very important product and, in this way, could help to promote its marketing.

Comparative transcriptional profiling of orange fruit in response to the biocontrol yeast Kloeckera apiculata and its active compounds.

BACKGROUND: The yeast Kloeckera apiculata strain 34-9 is an antagonist that shows biological control activity against the postharvest fungal pathogens of citrus. An antifungal compound, 2-phenylethanol (PEA), has been identified from the extract of K. apiculata. To better understand the molecular processes underlying the response of citrus fruit tissue to K. apiculata, the extract and PEA, microarray analyses were performed on navel oranges using an Affymetrix Citrus GeneChip. RESULTS: As many as 801, 339 and 608 differentially expressed genes (DEGs) were identified after the application of K. apiculata, the extract and PEA, respectively. In general, K. apiculata induced the expression of defence-related genes. In addition to chitinase and ß-1,3-glucanase, genes involved in ethylene (ET), jasmonic acid (JA), calcium signalling, MAPK signalling and phenylalanine metabolism were induced. In contrast, monodehydroascorbate reductase, superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and carotenoid biosynthesis genes were down-regulated. The expression profiles for the extract- and PEA-treated samples were similar to that found for yeast (sharing 57.4 % DEGs), with a significant increase in the transcript levels of defence-related genes. CONCLUSION: This study provides a global picture of the gene expression changes in navel oranges after the application of the antagonist yeast K. apiculata, its extract and PEA. The interpretation of the DEGs revealed new insight into the molecular processes that regulate the defence responses in orange tissue.

Fermentative capabilities and volatile compounds produced by Kloeckera/Hanseniaspora and Saccharomyces yeast strains in pure and mixed cultures during Agave tequilana juice fermentation.

The fermentative and aromatic capabilities of Kloeckera africana/Hanseniaspora vineae K1, K. apiculata/H. uvarum K2, and Saccharomyces cerevisiae S1 and S2 were studied in pure and mixed culture fermentations using Agave tequila juice as the culture medium. In pure and mixed cultures, Kloeckera/Hanseniaspora strains showed limited growth and sugar consumption, as well as low ethanol yield and productivity, compared to S. cerevisiae, which yielded more biomass, ethanol and viable cell concentrations. In pure and mixed cultures, S. cerevisiae presented a similar behaviour reaching high biomass production, completely consuming the sugar, leading to high ethanol production. Furthermore, the presence of S. cerevisiae strains in the mixed cultures promoted the production of higher alcohols, acetaldehyde and ethyl esters, whereas Kloeckera/Hanseniaspora strains stimulated the production of ethyl acetate and 2-phenyl ethyl acetate compounds.

Mechanisms of action for 2-phenylethanol isolated from Kloeckera apiculata in control of Penicillium molds of citrus fruits.

BACKGROUND: Green and blue mold decay, caused by Penicillium digitatum and P. italicum, respectively, are important postharvest diseases of citrus. Biocontrol by microbes is an alternative to synthetic fungicide application. In this study, the antagonistic yeast strain Kloeckera apiculata 34-9 was used to investigate the action mechanisms involved in the biocontrol of postharvest diseases. RESULTS: An antifungal substance, 2-phenylethanol (PEA), was isolated from K. apiculata and demonstrated to have antimicrobial activity against selected phytopathogenic fungi. Experiments on P. italicum cells identified the mitochondria and the nucleus as particularly sensitive to inhibition. Regulation of P. italicum gene expression was investigated using RNA-Seq. PEA up-regulated genes involved with the peroxisome, regulation of autophagy, phosphatidylinositol signaling system, protein processing in endoplasmic reticulum, fatty acid metabolism, and inhibited ribosome, RNA polymerase, DNA replication, amino acid biosynthesis, aminoacyl-tRNA biosynthesis and cell cycle. Inhibitory responses revealed by RNA-Seq suggest that PEA might compete for attachment on the active site of phenylalanyl-tRNA synthetase (PheRS). CONCLUSION: This study provided new insight on the mode of action of biocontrol yeast agents in controlling postharvest pathogenic fungi.

Effect of physicochemical factors on glycerol production by simultaneous cultures of wine micro-organisms using the response surface method.

AIM: To evaluate the effect of temperature, pH and SO2 on growth and glycerol production improvement by Saccharomyces cerevisiae mc2, Kloeckera apiculata mF and Oenococcus oeni X2L using the response surface method (RSM). METHODS AND RESULTS: Multifactorial design of cultures with physicochemical factors variations was performed. The micro-organisms grew in all cultures conditions. Overall, after 6 days yeasts prevailed, especially S. cerevisiae (10(9) CFU ml(-1)), while O. oeni reached 10(7) CFU ml(-1). At initial fixed pH 5·5, metabolic behaviour of cultures showed a temperature-dependent response. Total malate consumption occurred at 26°C, 50 mg l(-1) SO2. Glucose and pentoses utilization was highly modified when varying SO2. Ethanol showed negative interaction with temperature-SO2 relationship. At low SO2, glycerol and acetate production increased when temperature enhanced. Predictive results of RSM indicate that 26°C, 60·24 mg l(-1) SO2 and pH 5·5 were the optimal conditions for glycerol and organic acids synthesis compatible with wine quality. CONCLUSIONS: We propose a predictive condition to improve the performance of mixed cultures for must fermentations. SIGNIFICANCE AND IMPACT OF THE STUDY: To optimize the culture conditions to design mixed starters containing autochthonous yeasts and O. oeni strains for winemaking and to obtain products with high glycerol content, low acidity and maintenance of regional characteristics.

Glycerol production by Oenococcus oeni during sequential and simultaneous cultures with wine yeast strains.

Growth and fermentation patterns of Saccharomyces cerevisiae, Kloeckera apiculata, and Oenococcus oeni strains cultured in grape juice medium were studied. In pure, sequential and simultaneous cultures, the strains reached the stationary growth phase between 2 and 3 days. Pure and mixed K. apiculata and S. cerevisiae cultures used mainly glucose, producing ethanol, organic acids, and 4.0 and 0.1 mM glycerol, respectively. In sequential cultures, O. oeni achieved about 1 log unit at 3 days using mainly fructose and L-malic acid. Highest sugars consumption was detected in K. apiculata supernatants, lactic acid being the major end-product. 8.0 mM glycerol was found in 6-day culture supernatants. In simultaneous cultures, total sugars and L-malic acid were used at 3 days and 98% of ethanol and glycerol were detected. This study represents the first report of the population dynamics and metabolic behavior of yeasts and O. oeni in sequential and simultaneous cultures and contributes to the selection of indigenous strains to design starter cultures for winemaking, also considering the inclusion of K. apiculata. The sequential inoculation of yeasts and O. oeni would enhance glycerol production, which confers desirable organoleptic characteristics to wines, while organic acids levels would not affect their sensory profile.

Phenylethanol promotes adhesion and biofilm formation of the antagonistic yeast Kloeckera apiculata for the control of blue mold on citrus.

The yeast Kloeckera apiculata strain 34-9 is an antagonist with biological control activity against postharvest diseases of citrus fruit. In a previous study it was demonstrated that K. apiculata produced the aromatic alcohol phenylethanol. In the present study, we found that K. apiculata was able to form biofilm on citrus fruit and embed in an extracellular matrix, which created a mechanical barrier interposed between the wound surface and pathogen. As a quorum-sensing molecule, phenylethanol can promote the formation of filaments by K. apiculata in potato dextrose agar medium, whereas on the citrus fruit, the antagonist remains as yeast after being treated with the same concentration of phenylethanol. It only induced K. apiculata to adhere and form biofilm. Following genome-wide computational and experimental identification of the possible genes associated with K. apiculata adhesion, we identified nine genes possibly involved in triggering yeast adhesion. Six of these genes were significantly induced after phenylethanol stress treatment. This study provides a new model system of the biology of the antagonist-pathogen interactions that occur in the antagonistic yeast K. apiculata for the control of blue mold on citrus caused by Penicillium italicum.

Biofilm inhibition of spoilage bacteria by Argentinean fruit juices with antihypertensive activity.

Argentinean juices have been studied for their antihypertensive activity, the inhibition of bacteria biofilm formation and the effect on the viability of wine yeast. The influence of phenolic compounds on these activities was evaluated. These studies are the first step for the development of a new type of wine that includes grape must supplement with fruit juices with antihypertensive effect. All juices posses a high antihypertensive activity, higher than 50%. Strawberry juices and eureka lemon showed the highest activity, whereas clarified juices posses the lowest activity. All studied juices produce a high inhibition of bacteria biofilm formation, and the strawberry, orange and mandarin varieties not affect the growth or viability of yeast. Our results permit to conclude that it could be possible the use of these juices in a new type of wine or as a source of new antihypertensive agents for pharmaceutical industry.

Potentially pathogenic yeasts from soil of children's recreational areas in the city of Lódz (Poland).

OBJECTIVES: Yeasts may become potential human and animal pathogens, particularly for individuals with a depressed immune system. Their presence in the environment, especially in soil, may favour their spread into human ontocenoses. MATERIALS AND METHODS: Eighty-four soil samples obtained from 21 children's recreational sites in Lódz in autumn 2010 and spring 2011 were evaluated. The yeasts were isolated by classical microbiological methods and identified on the basis of morphological and biochemical features. RESULTS: The fungi were found in 73.8% and in 69.0% of the examined samples collected in autumn and spring, respectively. Among 97 isolates of yeasts, the species potentially pathogenic to humans and animals were Candida colliculosa, C. guilliermondii, C. humicola, C. inconspicua, C. lambica, C. lusitaniae, C. pelliculosa, C. tropicalis, Cryptococcus albidus, C. laurentii, C. neoformans, C. terreus, Kloeckera japonica, Geotrichum candidum, G. penicillatum, Rhodotorula mucilaginosa, R. glutinis, Saccharomyces cerevisiae, Sporobolomyces salmonicolor and Trichosporon cutaneum. The most frequently isolated fungi included the genus Cryptococcus (38 isolates) and two species: Rhodotorula glutinis (15), Trichosporon cutaneum (14). C. neoformans, an etiological factor of cryptococcal meningitis, was present in the sandpits of 3 kindergartens. The Candida species were identified from park playgrounds and school sports fields mainly in autumn 2010 (14 isolates), in spring 2011 - only 1 isolate. The concentration of fungal species in particular samples varied considerably, but in the majority of samples, fungi were present at concentration of up to 1×10(2) CFU/1 g of soil. CONCLUSIONS: Yeasts were present in the soil of parks, schools and kindergarten recreational areas; the fact may pose a health risk to humans, especially to children, and this type of biological pollution should be regarded as a potential public health concern.

A Saccharomyces cerevisiae wine strain inhibits growth and decreases Ochratoxin A biosynthesis by Aspergillus carbonarius and Aspergillus ochraceus.

The aim of this study was to select wine yeast strains as biocontrol agents against fungal contaminants responsible for the accumulation of ochratoxin A (OTA) in grape and wine and to dissect the mechanism of OTA detoxification by a Saccharomyces cerevisiae strain (DISAABA1182), which had previously been reported to reduce OTA in a synthetic must. All of the yeast strains tested displayed an ability to inhibit the growth of Aspergillus carbonarius both in vivo and in vitro and addition of culture filtrates from the tested isolates led to complete inhibition of OTA production. S. cerevisiae DISAABA1182 was selected and further tested for its capacity to inhibit OTA production and pks (polyketide synthase) transcription in A. carbonarius and Aspergillus ochraceus in vitro. In order to dissect the mechanism of OTA detoxification, each of these two fungi was co-cultured with living yeast cells exposed to yeast crude or to autoclaved supernatant: S. cerevisiae DISAABA1182 was found to inhibit mycelial growth and OTA production in both Aspergilli when co-cultured in the OTA-inducing YES medium. Moreover, a decrease in pks transcription was observed in the presence of living cells of S. cerevisiae DISAABA1182 or its supernatant, while no effects were observed on transcription of either of the constitutively expressed calmodulin and ß-tubulin genes. This suggests that transcriptional regulation of OTA biosynthetic genes takes place during the interaction between DISAABA1182 and OTA-producing Aspergilli.

Kloeckera taiwanica sp. nov., an ascomycetous apiculate yeast species isolated from mushroom fruiting bodies.

Three apiculate yeast strains, EJ7M09(T), GJ5M15 and GJ15M04, isolated from mushrooms in Taiwan were found to represent a novel species of the genus Kloeckera. The phylogenetically closest relative of this novel species is Hanseniaspora occidentalis, but the type strain of H. occidentalis differed by 4.6 % divergence (25 substitutions; 5 gaps) in the sequence of the D1/D2 domain of the large subunit rRNA gene. This difference clearly suggests that the three strains represent a distinct species. As none of the strains that were examined in this study produced ascospores or exhibited conjugation on common sporulation medium either alone or in a pairwise mixture, this species could be considered as an anamorphic member of the genus Hanseniaspora, and a novel species, Kloeckera taiwanica sp. nov., is proposed, with EJ7M09(T) ( = BCRC 23182(T) = CBS 11434(T)) as the type strain.

Fermentation of Agave tequilana juice by Kloeckera africana: influence of amino-acid supplementations.

This study aimed to improve the fermentation efficiency of Kloeckera africana K1, in tequila fermentations. We investigated organic and inorganic nitrogen source requirements in continuous K. africana fermentations fed with Agave tequilana juice. The addition of a mixture of 20 amino-acids greatly improved the fermentation efficiency of this yeast, increasing the consumption of reducing sugars and production of ethanol, compared with fermentations supplemented with ammonium sulfate. The preference of K. africana for each of the 20 amino-acids was further determined in batch fermentations and we found that asparagine supplementation increased K. africana biomass production, reducing sugar consumption and ethanol production (by 30, 36.7 and 45%, respectively) over fermentations supplemented with ammonium sulfate. Therefore, asparagine appears to overcome K. africana nutritional limitation in Agave juice. Surprisingly, K. africana produced a high concentration of ethanol. This contrasts to poor ethanol productivities reported for other non-Saccharomyces yeasts indicating a relatively high ethanol tolerance for the K. africana K1 strain. Kloeckera spp. strains are known to synthesize a wide variety of volatile compounds and we have shown that amino-acid supplements influenced the synthesis by K. africana of important metabolites involved in the bouquet of tequila. The findings of this study have revealed important nutritional limitations of non-Saccharomyces yeasts fermenting Agave tequilana juice, and have highlighted the potential of K. africana in tequila production processes.

Candida krusei and Kloeckera apis inhibit the causal agent of pineapple fusariosis, Fusarium guttiforme.

Studies based on microbial ecology and antagonistic interactions play an important role in the development of new alternative strategies in controlling plant pathogens and are relevant to further biotechnological applications. Antagonistic interactions between the yeasts Candida krusei and Kloeckera apis isolated from rotten pineapple fruits, and two isolates of the pathogenic filamentous fungus Fusarium guttiforme (Syn.: Fusarium subglutinans f. sp. ananas) resistant and susceptible to fungicide benzimidazole were studied in broth culture, and on plate assays. The yeasts significantly reduced Fusarium conidial germination after 24h of cocultivation in broth culture, and also mycelial growth on plate assays. Slide coculture appeared to show attachment of yeasts to the hyphal surface and also slight morphological abnormalities caused by C. krusei. Filtrates of cocultures of fungi and yeasts inhibited fungal growth, but filtrates of the yeast cultures alone did not, suggesting that the antagonistic action of the yeasts is inducible. The F. guttiforme isolate sensitive to benzimidazole was most affected by both yeasts in pineapple juice, reaching a maximum of 36.5 % germ tube inhibition. This isolate was also inhibited by yeasts in mycocinogenic plate assay. These results demonstrated that C. krusei and K. apis are effective in inhibiting F. guttiforme growth and that the mode of action is associated with hyperparasitism and mycocinogenic activity.

Characterization of wines produced by mixed culture of autochthonous yeasts and Oenococcus oeni from the northwest region of Argentina.

Two autochthonous yeasts from the northwest region of Argentina, Kloeckera apiculata mc1 and Saccharomyces cerevisiae mc2, were used as pure or mixed starter cultures in microvinification trials conducted in Malbec red must. Also, the effect of Oenococcus oeni X(2)L was evaluated. S. cerevisiae mc2 showed adequate growth and fermentative activity in single and composite fermentations, producing standard concentration of ethanol. The amount of esters was higher in fermentations conducted using mixed yeast starters. Independent of the timing of inoculation of O. oeni, this malolactic bacterium completely depleted malic acid. Sensory evaluation indicated that young wines fermented with mixed yeast cultures and sequential inoculation of O. oeni were preferred, achieving the highest scores for positive descriptors and they allowed better control of the sensory quality. Consequently, this study proposes inclusion of autochthonous K. apiculata mc1 as an adjunct culture to S. cerevisiae mc2 during Malbec must fermentation to improve the organoleptic properties of red wines. Furthermore, sequential inoculation of O. oeni X(2)L should be carried out after completion of the alcoholic fermentation to enhance sensory characteristics.

Improvement of growth, fermentative efficiency and ethanol tolerance of Kloeckera africana during the fermentation of Agave tequilana juice by addition of yeast extract.

BACKGROUND: The aim of this work was to improve the productivity and yield of tequila fermentation and to propose the use of a recently isolated non-Saccharomyces yeast in order to obtain a greater diversity of flavour and aroma of the beverage. For that, the effects of the addition of different nitrogen (N) sources to Agave tequilana juice on the growth, fermentative capacity and ethanol tolerance of Kloeckera africana and Saccharomyces cerevisiae were studied and compared. RESULTS: Kloeckera africana K1 and S. cerevisiae S1 were cultured in A. tequilana juice supplemented with ammonium sulfate, diammonium phosphate or yeast extract. Kloeckera africana did not assimilate inorganic N sources, while S. cerevisiae utilised any N source. Yeast extract stimulated the growth, fermentative capacity and alcohol tolerance of K. africana, giving kinetic parameter values similar to those calculated for S. cerevisiae. CONCLUSION: This study revealed the importance of supplementing A. tequilana juice with a convenient N source to achieve fast and complete conversion of sugars in ethanol, particularly in the case of K. africana. This yeast exhibited similar growth and fermentative capacity to S. cerevisiae. The utilisation of K. africana in the tequila industry is promising because of its variety of synthesised aromatic compounds, which would enrich the attributes of this beverage.

Influence of indigenous yeasts on the fermentation and volatile profile of plum brandies.

The aim of this study was to determine the influence of different yeasts isolated from fresh blue plum fruits (Aureobasidium sp.) and spontaneously fermenting plum musts (Kloeckera apiculata and Saccharomyces cerevisiae), as well as commercial wine and distillery strains, on the fermentation and chemical composition of plum brandies. Gas chromatography methods were used to detect major volatile components. The most rapid fermentation occurred in musts inoculated with S. cerevisiae. However, the highest concentration of ethanol was detected in samples after spontaneous fermentation (8.40% v/v). Plum brandies obtained after distillation contained from 66.3 (K. apiculata) up to 74.3% v/v ethanol (spontaneous fermentation). The samples after spontaneous fermentation were distinguished by a high content of acetoin, ethyl acetate and total esters, accompanied by a low level of methanol and fusel alcohols. Non-Saccharomyces yeasts were responsible for higher concentrations of esters and methanol, while S. cerevisiae strains resulted in increased levels of higher alcohols. It was also found that isolated indigenous strains of S. cerevisiae synthesized relatively low amounts of higher alcohols compared to commercial cultures. Samples obtained using the distillery strain of S. cerevisiae received the highest score (18.2) during sensory analysis and were characterized by a well-harmonised taste and aroma.

The inter-generic fungicidal activity of Xanthophyllomyces dendrorhous.

In this study, the existence of intra-specific and inter-generic fungicidal activity in Xanthophyllomyces dendrorhous and Phaffia rhodozyma strains isolated from different regions of the earth was examined. Assays were performed under several culture conditions, showing that all the analyzed X. dendrorhous and P. rhodozyma strains have killing activity against Kloeckera apiculata, Rhodotorula sloffiae, and R. minuta. This activity was greater in rich media at a pH from 4.6 to 5.0. Extracellular protein extracts with fungicidal activity were obtained from cultures of all strains, and their characterization suggested that a protein of 33 kDa is the antifungal factor. According to peptide mass fingerprinting and an analysis of the results with the MASCOT search engine, this protein was identified as an aspartic protease. Additionally, extrachromosomal double-stranded DNA elements (dsDNAs) were observed in all X. dendrorhous and P. rhodozyma strains. Although there is a high variability, two dsDNAs of 5.4 and 6.8 kb are present in all strains.

Three new species of bipolar budding yeasts of the genus Hanseniaspora and its anamorph Kloeckera isolated in Thailand.

In the course of a survey of yeast biodiversity in the natural substrates in Thailand, eight strains were found to represent three hitherto undescribed species of Hanseniaspora/Kloeckera. They were isolated from insect frass, flower, lichen, rotted fruit and rotted wood. Based on the morphological and physiological characteristics, and sequences of D1/D2 domain, six strains represent a single species of the genus Hanseniaspora, described as Hanseniaspora thailandica sp. nov. (type BCC 14938(T)=NBRC 104216(T)=CBS 10841(T)), and another strain as Hanseniaspora singularis sp. nov. (type BCC 15001(T)=NBRC 104214(T)=CBS 10840(T)). A further strain, which belongs to Kloeckera and does not produce ascospores, is described as Kloeckera hatyaiensis sp. nov. (type BCC 14939(T)=NBRC 104215(T)=CBS 10842(T)). Strains belonging to H. thailandica sp. nov. differed by 17-19 nucleotide substitutions from Hanseniaspora meyeri, the closest species. DNA reassociation between the two taxa showed 30-48% relatedness. Kloeckera hatyaiensis sp. nov. and H. singularis sp. nov. differed by eight and 16 nucleotide substitutions with one gap from the nearest species, Hanseniaspora clermontiae and Hanseniaspora valbyensis, respectively.

Influence of wine-related physicochemical factors on the growth and metabolism of non-Saccharomyces and Saccharomyces yeasts in mixed culture.

The influence of two physicochemical factors involved in winemaking, temperature and SO(2), on the kinetics and metabolic behavior of Kloeckera apiculata and Saccharomyces cerevisiae was examined. Highest biomass was reached at 15 and 25 degrees C for K. apiculata and S. cerevisiae, respectively. Pure cultures of K. apiculata died off early with increasing temperature, but in co-culture with S. cerevisiae it showed higher viability and a change in the death curve from exponential to linear. Statistical analysis revealed that metabolite production was significantly different for the three cultures and also at the different fermentation temperatures. Besides, the interaction between culture type and temperature was significant. At temperatures from 15 to 30 degrees C the mixed culture showed similar ethanol and lower acetic acid production compared with a pure culture of K. apiculata. SO(2) addition slightly increased survival of the non-Saccharomyces species in pure and mixed cultures. Statistical evaluation indicated that culture type and SO(2) addition significantly affected metabolite production, but the interaction between culture and SO(2) was not significant. These results contribute to current knowledge of enological factors and their effect on prevalence and fermentative activities of the composite yeast flora and the statistical significance emphasizes the importance of the combined influence of the culture type and physicochemical factors on the production of fermentation metabolites.

Selective sugar consumption by apiculate yeasts.

Selective consumption of glucose and fructose among apiculate yeasts was evaluated. Results showed that Hanseniaspora guilliermondii and H. uvarum type strains were fructosophilic, unlike the other type strains. The difference in glucose and fructose use was confirmed in different media and throughout sugar consumption. Selective consumption of fructose is widely diffused among apiculate wine yeasts and could positively interfere with fermentation behaviour of Saccharomyces cerevisiae.