Cross-kingdom chemical communication drives a heritable, mutually beneficial prion-based transformation of metabolism.

In experimental science, organisms are usually studied in isolation, but in the wild, they compete and cooperate in complex communities. We report a system for cross-kingdom communication by which bacteria heritably transform yeast metabolism. An ancient biological circuit blocks yeast from using other carbon sources in the presence of glucose. [GAR(+)], a protein-based epigenetic element, allows yeast to circumvent this "glucose repression" and use multiple carbon sources in the presence of glucose. Some bacteria secrete a chemical factor that induces [GAR(+)]. [GAR(+)] is advantageous to bacteria because yeast cells make less ethanol and is advantageous to yeast because their growth and long-term viability is improved in complex carbon sources. This cross-kingdom communication is broadly conserved, providing a compelling argument for its adaptive value. By heritably transforming growth and survival strategies in response to the selective pressures of life in a biological community, [GAR(+)] presents a unique example of Lamarckian inheritance.

Recombination, admixture and genome instability shape the genomic landscape of Saccharomyces cerevisiae derived from spontaneous grape ferments.

Cultural exchange of fermentation techniques has driven the spread of Saccharomyces cerevisiae across the globe, establishing natural populations in many countries. Despite this, Oceania is thought to lack native populations of S. cerevisiae, only being introduced after colonisation. Here we investigate the genomic landscape of 411 S. cerevisiae isolated from spontaneous grape fermentations in Australia across multiple locations, years, and grape cultivars. Spontaneous fermentations contained highly recombined mosaic strains that exhibited high levels of genome instability. Assigning genomic windows to putative ancestral origin revealed that few closely related starter lineages have come to dominate the genetic landscape, contributing most of the genetic variation. Fine-scale phylogenetic analysis of loci not observed in strains of commercial wine origin identified widespread admixture with European derived beer yeast along with three independent admixture events from potentially endemic Oceanic lineages that was associated with genome instability. Finally, we investigated Australian ecological niches for basal isolates, identifying phylogenetically distinct S. cerevisiae of non-European, non-domesticated origin associated with admixture loci. Our results illustrate the effect commercial use of microbes may have on local microorganism genetic diversity and demonstrates the presence of non-domesticated, potentially endemic lineages of S. cerevisiae in Australian niches that are actively admixing.

Ancient DNA from a lost Negev Highlands desert grape reveals a Late Antiquity wine lineage.

Recent excavations of Late Antiquity settlements in the Negev Highlands of southern Israel uncovered a society that established commercial-scale viticulture in an arid environment [D. Fuks et al., Proc. Natl. Acad. Sci. U.S.A. 117, 19780-19791 (2020)]. We applied target-enriched genome-wide sequencing and radiocarbon dating to examine grapevine pips that were excavated at three of these sites. Our analyses revealed centuries long and continuous grape cultivation in the Southern Levant. The genetically diverse pips also provided clues to ancient cultivation strategies aimed at improving agricultural productivity and ensuring food security. Applying genomic prediction analysis, a pip dated to the eighth century CE was determined to likely be from a white grape, to date the oldest to be identified. In a kinship analysis, another pip was found to be descendant from a modern Greek cultivar and was thus linked with several popular historic wines that were once traded across the Byzantine Empire. These findings shed light on historical Byzantine trading networks and on the genetic contribution of Levantine varieties to the classic Aegean landscape.

SO2 and copper tolerance exhibit an evolutionary trade-off in Saccharomyces cerevisiae.

Copper tolerance and SO2 tolerance are two well-studied phenotypic traits of Saccharomyces cerevisiae. The genetic bases of these traits are the allelic expansion at the CUP1 locus and reciprocal translocation at the SSU1 locus, respectively. Previous work identified a negative association between SO2 and copper tolerance in S. cerevisiae wine yeasts. Here we probe the relationship between SO2 and copper tolerance and show that an increase in CUP1 copy number does not always impart copper tolerance in S. cerevisiae wine yeast. Bulk-segregant QTL analysis was used to identify variance at SSU1 as a causative factor in copper sensitivity, which was verified by reciprocal hemizygosity analysis in a strain carrying 20 copies of CUP1. Transcriptional and proteomic analysis demonstrated that SSU1 over-expression did not suppress CUP1 transcription or constrain protein production and provided evidence that SSU1 over-expression induced sulfur limitation during exposure to copper. Finally, an SSU1 over-expressing strain exhibited increased sensitivity to moderately elevated copper concentrations in sulfur-limited medium, demonstrating that SSU1 over-expression burdens the sulfate assimilation pathway. Over-expression of MET 3/14/16, genes upstream of H2S production in the sulfate assimilation pathway increased the production of SO2 and H2S but did not improve copper sensitivity in an SSU1 over-expressing background. We conclude that copper and SO2 tolerance are conditional traits in S. cerevisiae and provide evidence of the metabolic basis for their mutual exclusivity. These findings suggest an evolutionary driver for the extreme amplification of CUP1 observed in some yeasts.

Genome editing of a recalcitrant wine grape genotype by lipofectamine-mediated delivery of CRISPR/Cas9 ribonucleoproteins to protoplasts.

The main bottleneck in the application of biotechnological breeding methods to woody species is due to the in vitro regeneration recalcitrance shown by several genotypes. On the other side, woody species, especially grapevine (Vitis vinifera L.), use most of the pesticides and other expensive inputs in agriculture, making the development of efficient approaches of genetic improvement absolutely urgent. Genome editing is an extremely promising technique particularly for wine grape genotypes, as it allows to modify the desired gene in a single step, preserving all the quality traits selected and appreciated in elite varieties. A genome editing and regeneration protocol for the production of transgene-free grapevine plants, exploiting the lipofectamine-mediated direct delivery of CRISPR-Cas9 ribonucleoproteins (RNPs) to target the phytoene desaturase gene, is reported. We focused on Nebbiolo (V. vinifera), an extremely in vitro recalcitrant wine genotype used to produce outstanding wines, such as Barolo and Barbaresco. The use of the PEG-mediated editing method available in literature and employed for highly embryogenic grapevine genotypes did not allow the proper embryo development in the recalcitrant Nebbiolo. Lipofectamines, on the contrary, did not have a negative impact on protoplast viability and plant regeneration, leading to the obtainment of fully developed edited plants after about 5 months from the transfection. Our work represents one of the first examples of lipofectamine use for delivering editing reagents in plant protoplasts. The important result achieved for the wine grape genotype breeding could be extended to other important wine grape varieties and recalcitrant woody species.

Flint glass bottles cause white wine aroma identity degradation.

Due to marketing recommendations, white wines are often bottled in flint glass to improve aesthetics and showcase wine color. Although this practice is known to cause a wine fault, the influence of light on the fruity and flowery aromatic profile of wine is unknown. The aim of this study was to investigate the changes to the white wine volatilome under typical supermarket shelf conditions, using 1,052 bottles of 24 white wines. After only 7 d of shelf life in flint glass bottles, a dramatic loss in terpenes (10 to 30%) and norisoprenoids (30 to 70%) was recorded, whereas colored glass bottles did not evidence such behavior even after 50 d, and darkness preserved the wine's fruity and flowery aromatic integrity. We also proposed an alternative mechanism for the insurgence of the lightstrike off-odor, which takes the varietal aroma loss into account. In light of this understanding of the flint glass negative impact on white wine aroma identity and sensorial character, this packaging should be strongly discouraged. The same findings should be valid for a wide range of several daily consumed foodstuff where transparent packaging is used.

Impact on wine sales of removing the largest serving size by the glass: An A-B-A reversal trial in 21 pubs, bars, and restaurants in England.

BACKGROUND: Interventions that alter aspects of the physical environments in which unhealthy behaviours occur have the potential to change behaviour at scale, i.e., across populations, and thereby decrease the risk of several diseases. One set of such interventions involves reducing serving sizes, which could reduce alcohol consumption. The effect of modifying the available range of serving sizes of wine in a real-world setting is unknown. We aimed to assess the impact on the volume of wine sold of removing the largest serving size by the glass from the options available in licensed premises. METHODS AND FINDINGS: The study was conducted between September 2021 and May 2022 in 21 licensed premises in England that sold wine by the glass in serving sizes greater than 125 ml (i.e., 175 ml or 250 ml) and used an electronic point of sale till system. It used an A-B-A reversal design, set over 3 four-weekly periods. "A" represented the nonintervention periods during which standard serving sizes were served and "B" the intervention period when the largest serving size for a glass of wine was removed from the existing range in each establishment: 250 ml (18 premises) or 175 ml (3 premises). The primary outcome was the daily volume of wine sold, extracted from sales data. Twenty-one premises completed the study, 20 of which did so per protocol and were included in the primary analysis. After adjusting for prespecified covariates, the intervention resulted in -420·8 millilitres (ml) (95% confidence intervals (CIs) -681·4 to -160·2 p = 0·002) or -7·6% (95% CI -12·3%, -2·9%) less wine being sold per day. There was no evidence that sales of beer and cider or total daily revenues changed but the study was not powered to detect differences in these outcomes. The main study limitation is that we were unable to assess the sales of other alcoholic drinks apart from wine, beer, and cider, estimated to comprise approximately 30% of alcoholic drinks sold in participating premises. CONCLUSIONS: Removing the largest serving size of wine by the glass from those available reduced the volume of wine sold. This promising intervention for decreasing alcohol consumption across populations merits consideration as part of alcohol licensing regulations. TRIAL REGISTRATION: ISRCTN https://doi.org/10.1186/ISRCTN33169631; OSF https://osf.io/xkgdb.

Vineyard microclimate alterations induced by black inter-row mulch through transcriptome reshaped the flavoromics of cabernet sauvignon grapes.

BACKGROUND: Weed control is essential for agricultural floor management in vineyards and the inter-row mulching is an eco-friendly practice to inhibit weed growth via filtering out photosynthetically active radiation. Besides weed suppression, inter-row mulching can influence grapevine growth and the accumulation of metabolites in grape berries. However, the complex interaction of multiple factors in the field challenges the understanding of molecular mechanisms on the regulated metabolites. In the current study, black geotextile inter-row mulch (M) was applied for two vintages (2016-2017) from anthesis to harvest. Metabolomics and transcriptomics analysis were conducted in two vintages, aiming to provide insights into metabolic and molecular responses of Cabernet Sauvignon grapes to M in a semi-arid climate. RESULTS: Upregulation of genes related to photosynthesis and heat shock proteins confirmed that M weakened the total light exposure and grapes suffered heat stress, resulting in lower sugar-acid ratio at harvest. Key genes responsible for enhancements in phenylalanine, glutamine, ornithine, arginine, and C6 alcohol concentrations, and the downward trend in ε-viniferin, anthocyanins, flavonols, terpenes, and norisoprenoids in M grapes were identified. In addition, several modules significantly correlated with the metabolic biomarkers through weighted correlation network analysis, and the potential key transcription factors regulating the above metabolites including VviGATA11, VviHSFA6B, and VviWRKY03 were also identified. CONCLUSION: This study provides a valuable overview of metabolic and transcriptomic responses of M grapes in semi-arid climates, which could facilitate understanding the complex regulatory network of metabolites in response to microclimate changes.

Nakazawaea atacamensis f.a., sp. nov. a novel nonconventional fermentative ascomycetous yeast species from the Atacama Desert.

In this study, we describe Nakazawaea atacamensis f. a., sp. nov., a novel species obtained from Neltuma chilensis plant samples in Chile's hyperarid Atacama Desert. In total, three strains of N. atacamensis were obtained from independent N. chilensis samples (synonym Prosopis chilensis, Algarrobo). Two strains were obtained from bark samples, while the third strain was obtained from bark-exuded gum from another tree. The novel species was defined using molecular characteristics and subsequently characterized with respect to morphological, physiological, and biochemical properties. A neighbor-joining analysis using the sequences of the D1/D2 domains of the large subunit ribosomal RNA gene revealed that N. atacamensis clustered with Nakazawaea pomicola. The sequence of N. atacamensis differed from closely related species by 1.3%-5.2% in the D1/D2 domains. A phylogenomic analysis based on single-nucleotide polymorphism's data confirms that the novel species belongs to the genus Nakazawaea, where N. atacamensis clustered with N. peltata. Phenotypic comparisons demonstrated that N. atacamensis exhibited distinct carbon assimilation patterns compared to its related species. Genome sequencing of the strain ATA-11A-BT revealed a genome size of approximately 12.4 Mbp, similar to other Nakazawaea species, with 5116 protein-coding genes annotated using InterProScan. In addition, N. atacamensis exhibited the capacity to ferment synthetic wine must, representing a potential new yeast for mono or co-culture wine fermentations. This comprehensive study expands our understanding of the genus Nakazawaea and highlights the ecological and industrial potential of N. atacamensis in fermentation processes. The holotype of N. atacamensis sp. nov. is CBS 18375T . The Mycobank number is MB 849680.

Predictability of the community-function landscape in wine yeast ecosystems.

Predictively linking taxonomic composition and quantitative ecosystem functions is a major aspiration in microbial ecology, which must be resolved if we wish to engineer microbial consortia. Here, we have addressed this open question for an ecological function of major biotechnological relevance: alcoholic fermentation in wine yeast communities. By exhaustively phenotyping an extensive collection of naturally occurring wine yeast strains, we find that most ecologically and industrially relevant traits exhibit phylogenetic signal, allowing functional traits in wine yeast communities to be predicted from taxonomy. Furthermore, we demonstrate that the quantitative contributions of individual wine yeast strains to the function of complex communities followed simple quantitative rules. These regularities can be integrated to quantitatively predict the function of newly assembled consortia. Besides addressing theoretical questions in functional ecology, our results and methodologies can provide a blueprint for rationally managing microbial processes of biotechnological relevance.

Mass spectrometry in the study of wood compounds released in the barrel-aged wine and spirits.

Aging of wines and spirits in wooden barrels is an industrial process used to stabilize the color, to improve the limpidity and to enrich the sensorial characteristics of the products. In red wines, the oxygen that permeates through the wood staves promotes the oxidization of polyphenols and the formation of new pigments with consequent stabilization of the wine color. Barrel aging of spirits, such as brandy, whisky, rum, and grappa is finalized to enrich their aroma and improve their sensorial characteristics by the contribute of the compounds released by the wood. Oak is the wood type mostly used in making barrels; however, an increasing interest in the use of chestnut, cherry, acacia, and in less extent, ash and mulberry, has been observed in the recent years. Gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry are the main techniques used to characterize respectively the volatile and polar metabolites released by the wood barrels in the products. In this article are reported the recent advancements in this field.

Exploring future applications of the apiculate yeast Hanseniaspora.

As a metaphor, lemons get a bad rap; however the proverb 'if life gives you lemons, make lemonade' is often used in a motivational context. The same could be said of Hanseniaspora in winemaking. Despite its predominance in vineyards and grape must, this lemon-shaped yeast is underappreciated in terms of its contribution to the overall sensory profile of fine wine. Species belonging to this apiculate yeast are known for being common isolates not just on grape berries, but on many other fruits. They play a critical role in the early stages of a fermentation and can influence the quality of the final product. Their deliberate addition within mixed-culture fermentations shows promise in adding to the complexity of a wine and thus provide sensorial benefits. Hanseniaspora species are also key participants in the fermentations of a variety of other foodstuffs ranging from chocolate to apple cider. Outside of their role in fermentation, Hanseniaspora species have attractive biotechnological possibilities as revealed through studies on biocontrol potential, use as a whole-cell biocatalyst and important interactions with Drosophila flies. The growing amount of 'omics data on Hanseniaspora is revealing interesting features of the genus that sets it apart from the other Ascomycetes. This review collates the fields of research conducted on this apiculate yeast genus.

Alcohol Consumption and the Diversity of the Oral Microbiome in Postmenopausal Women.

BACKGROUND: Alcohol reduces neutrophil function and decreases salivary flow, which could affect the composition of the oral microbiome. OBJECTIVE: We hypothesized that the α- and ß-diversity of the oral microbiome and the relative abundance of bacterial taxa would differ by frequency and type of alcohol consumption. METHODS: We used a food frequency questionnaire to assess the frequency of consumption of beer, wine, and liquor (drinks/week) in a sample of 1179 postmenopausal women in the Osteoporosis and Periodontal Disease Study. Women were categorized as nondrinkers, drinking <1 drink/wk, ≥1 to <7 drinks/wk, or ≥7 drinks/wk for total alcohol consumption and for beer, wine, and liquor consumption. The composition and diversity of the oral microbiome was assessed from subgingival plaque samples using 16S ribosomal RNA amplicon sequencing. Permutational multivariate analysis of variance (PERMANOVA) was used to examine ß-diversity (between-sample diversity) in the microbiome between alcohol consumption categories. Analysis of covariance was used to examine the mean α-diversity (within-sample diversity), assessed by the Shannon index (species evenness), Chao1 index (species richness), and observed operational taxonomic unit (OTU) count and the mean relative abundance of 245 bacterial taxa across alcohol consumption categories. RESULTS: Over half of the participants (67%) consumed alcohol, with 14% reporting ≥1 drink/d. The ß-diversity across categories of total alcohol consumption, but not categories of alcohol type, was statistically significantly different (P for PERMANOVA = 0.016). Mean α-diversity measures were statistically significantly higher (P < 0.05) in the highest category of total alcohol and wine consumption compared to nondrinkers; no significant associations were found for beer or liquor consumption. The relative abundance of 1 OTU, Selenomonassp._oral_taxon_133, was significantly lower in the highest level of total alcohol consumption compared to nondrinkers after adjustment for multiple comparisons. CONCLUSIONS: Alcohol consumption was associated with the diversity and composition of the subgingival microbiome.

QTL mapping reveals novel genes and mechanisms underlying variations in H2S production during alcoholic fermentation in Saccharomyces cerevisiae.

Saccharomyces cerevisiae requirement for reduced sulfur to synthesize methionine and cysteine during alcoholic fermentation, is mainly fulfilled through the sulfur assimilation pathway. Saccharomyces cerevisiae reduces sulfate into sulfur dioxide (SO2) and sulfide (H2S), whose overproduction is a major issue in winemaking, due to its negative impact on wine aroma. The amount of H2S produced is highly strain-specific and also depends on SO2 concentration, often added to grape must. Applying a bulk segregant analysis to a 96-strain-progeny derived from two strains with different abilities to produce H2S, and comparing allelic frequencies along the genome of pools of segregants producing contrasting H2S quantities, we identified two causative regions involved in H2S production in the presence of SO2. A functional genetic analysis allowed the identification of variants in four genes able to impact H2S formation, viz; ZWF1, ZRT2, SNR2, and YLR125W, and involved in functions and pathways not associated with sulfur metabolism until now. These data point out that, in wine fermentation conditions, redox status, and zinc homeostasis are linked to H2S formation while providing new insights into the regulation of H2S production, and a new vision of the interplay between the sulfur assimilation pathway and cell metabolism.

Investigation on screening, identification, and fermentation characteristics of Yunnan olive in the fermented liquid utilizing five strains of Saccharomyces cerevisiae.

Refined indigenous Saccharomyces cerevisiae can enhance refinement, sophistication, and subtlety of fruit wines by showcasing exceptional regional characteristics. In order to identify exceptional indigenous S. cerevisiae strains from Yunnan olive, this study isolated 60 yeast strains from wild Yunnan olive fermentation mash. The five S. cerevisiae strains were subjected to morphological and molecular biological identification, followed by evaluation of their fermentation performance, ethanol production capacity, ester production capacity, H2S production capacity, killing capacity, and tolerance. Strains LJM-4, LJM-10, and LJM-26 exhibited robust tolerance to 6% ethanol volume fraction, pH 2.8, sucrose concentration of 400 g/L, SO2 concentration of 0.3 g/L, glucose concentration of 400 g/L at both 40 °C and 15 °C. Additionally, strain LJM-10 demonstrated a faster fermentation rate compared to the other strains. Among the tested S. cerevisiae strains evaluated in this study for olive wine fermentation process in Yunnan region; strain LJM-10 displayed superior abilities in terms of ester and ethanol production while exhibiting the lowest H2S production levels. These findings suggest that strain LJM-10 holds great potential as an excellent candidate for optimizing fruit wine S. cerevisiae fermentation processes in Yunnan olive fruit wine.

Recovery and characterization of ß-glucosidase-producing non-Saccharomyces yeasts from the fermentation broth of Vitis labruscana Baily × Vitis vinifera L. for investigation of their fermentation characteristics.

The present study focuses on investigating 60 strains of yeast isolated from the natural fermentation broth of Vitis labruscana Baily × Vitis vinifera L. These strains underwent screening using lysine culture medium and esculin culture medium, resulting in the identification of 27 local non-Saccharomyces yeast strains exhibiting high ß-glucosidase production. Subsequent analysis of their fermentation characteristics led to the selection of four superior strains (Z-6, Z-11, Z-25, and Z-58) with excellent ß-glucosidase production and fermentation performance. Notably, these selected strains displayed a dark coloration on esculin medium and exhibited robust gas production during Duchenne tubules' fermentation test. Furthermore, all four non-Saccharomyces yeast strains demonstrated normal growth under specific conditions including SO2 mass concentration ranging from 0.1 to 0.3 g/L, temperature between 25 and 30 °C, glucose mass concentration ranging from 200 to 400 g/L, and ethanol concentration at approximately 4%. Molecular biology identification confirmed that all selected strains belonged to Pichia kudriavzevii species which holds great potential for wine production.

Succinic acid production by wine yeasts and the influence of GABA and glutamic acid.

As a consequence of alcoholic fermentation (AF) in wine, several compounds are released by yeasts, and some of them are linked to the general quality and mouthfeel perceptions in wine. However, others, such as succinic acid, act as inhibitors, mainly of malolactic fermentation. Succinic acid is produced by non-Saccharomyces and Saccharomyces yeasts during the initial stages of AF, and the presence of some amino acids such as γ-aminobutyric acid (GABA) and glutamic acid can increase the concentration of succinic acid. However, the influence of these amino acids on succinic acid production has been studied very little to date. In this work, we studied the production of succinic acid by different strains of non-Saccharomyces and Saccharomyces yeasts during AF in synthetic must, and the influence of the addition of GABA or glutamic acid or a combination of both. The results showed that succinic acid can be produced by non-Saccharomyces yeasts with values in the range of 0.2-0.4 g/L. Moreover, the addition of GABA or glutamic acid can increase the concentration of succinic acid produced by some strains to almost 100 mg/L more than the control, while other strains produce less. Consequently, higher succinic acid production by non-Saccharomyces yeast in coinoculated fermentations with S. cerevisiae strains could represent a risk of inhibiting Oenococcus oeni and therefore the MLF.

Molecularly imprinted dispersive micro solid-phase extraction and tandem derivatization for the determination of histamine in fermented wines.

Histamine causes allergic reactions and can serve as an indicator for assessing food quality. This study designed and developed a dispersive micro solid-phase extraction (D-µSPE) method that combined the advantages of dispersive liquid-liquid extraction and solid-phase extraction (SPE). Molecularly imprinted polymers (MIPs) were employed as the solid phase in the D-µSPE method to extract histamine in wine samples. We used microwave energy to significantly reduce the synthesis time, achieving an 11.1-fold shorter synthesis time compared to the conventional MIP synthetic method. Under optimized D-µSPE conditions, our results showed that the dispersive solvent could effectively increase the adsorption performance of MIPs in wine samples by 97.7%. To improve the sensitivity of histamine detection in gas chromatography-mass spectrometry, we employed the microwave-assisted tandem derivatization method to reuse excess derivatization reagents and reduce energy consumption and reaction time. Calibration curves were constructed for wine samples spiked with 0-400 nmol histamine using the standard addition method, resulting in good linearity with a coefficient of determination of 0.999. The intra- and inter-batch relative standard deviations of the slope and intercept were < 0.7% and < 5.3%, respectively. The limits of quantitation and detection were 0.4 nmol and 0.1 nmol, respectively. The developed method was successfully applied to analyze the histamine concentration in 10 commercial wine samples. In addition, the AGREEprep tool was used to evaluate the greenness performance of the developed method, which obtained a higher score than the other reported methods.

Non-target estrogenic screening of 60 pesticides, six plant protection products, and tomato, grape, and wine samples by planar chromatography combined with the planar yeast estrogen screen bioassay.

For non-target residue analysis of xenoestrogens in food, sophisticated chromatographic-mass spectrometric techniques lack in biological effect detection. Various in vitro assays providing sum values encounter problems when opposing signals are present in a complex sample. Due to physicochemical signal reduction, cytotoxic or antagonistic effect responses, the resulting sum value is falsified. Instead, the demonstrated non-target estrogenic screening with an integrated planar chromatographic separation differentiated opposing signals, detected and prioritized important estrogenic compounds, and directly assigned tentatively the responsible compounds. Sixty pesticides were investigated, ten of which showed estrogenic effects. Exemplarily, half-maximal effective concentrations and 17ß-estradiol equivalents were determined. Estrogenic pesticide responses were confirmed in six tested plant protection products. In food, such as tomato, grape, and wine, several compounds with an estrogenic effect were detected. It showed that rinsing with water was not sufficient to remove selected residues and illustrated that, though not usually performed for tomatoes, peeling would be more appropriate. Though not in the focus, reaction or breakdown products that are estrogenic were detected, underlining the great potential of non-target planar chromatographic bioassay screening for food safety and food control.

Strain specific Starmerella bacillaris and Saccharomyces cerevisiae interactions in mixed fermentations.

AIMS: Yeast interactions have a key role in the definition of the chemical profile of the wines. For this reason, winemakers are increasingly interested in mixed fermentations, employing Saccharomyces cerevisiae and non-Saccharomyces strains. However, the outcome of mixed fermentations is often contradictory because there is a great variability among strains within species. Previously, it was demonstrated that the loss of culturability of Starmerella bacillaris in mixed fermentations with S. cerevisiae was due to the physical contact between cells. Therefore, to further explore previous observations, the interaction mechanisms among different strains of Starm. bacillaris and S. cerevisiae during mixed fermentations were investigated. METHODS AND RESULTS: Fermentations were conducted under conditions that allow physical contact between cells (flasks) but also using a double-compartment fermentation system in which cells of both species were kept separate. The role of competition for nutrients and antimicrobial compounds production on yeast-yeast interaction mechanisms was also investigated. Three Starm. bacillaris and three S. cerevisiae strains were used to investigate if interaction mechanisms are modulated in a strain-specific way. Both species populations were affected by physical contact, particularly Starm. bacillaris that lost its culturability during fermentation. In addition, loss of culturability of Starm. bacillaris strains was observed earlier in flasks than in the double-compartment system. The phenomena observed occurred in a strain couple-dependent way. Starm. bacillaris disappearance seemed to be independent of nutrient depletion or the presence of inhibitory compounds (which were not measured in this study). CONCLUSION: Overall, the results of the present study reveal that cell-to-cell contact plays a role in the early death of non-Saccharomyces but the extent to which it is observed depends greatly on the Starm. bacillaris/S. cerevisiae strains tested.