Cells of the yeast Saccharomyces cerevisiae can undergo profound molecular, physiological and mor... more Cells of the yeast Saccharomyces cerevisiae can undergo profound molecular, physiological and morphological modifications in response to a limited supply of essential nutrients, in particular carbon or nitrogen sources. These include a shift in transcription patterns, the modification of the cell cycle, a change in budding pattern and strongly polarised growth. Cells having undergone these modifications do not separate after cell division is completed and form chains of elongated cells called pseudohyphae or filaments. Cells growing as filaments are able to invade agar plates and other substrates, a phenomenon referred to as invasive growth. A network of signal transduction pathways governs this switch from yeast-like growth to pseudohyphal and invasive growth. Important elements of this network have been identified, including nutrient signal-receptors, GTP-binding proteins, components of the pheromonedependent MAP kinase cascade, cAMP, and several transcription factors. In this review, we summarise our current knowledge in this rapidly progressing field. We focus particularly on the interactions between several signal transduction modules and on the different transcription factors, which are regulated by these signalling modules.
Geographic origin and terroir are very important parameters for wine and significantly impact pri... more Geographic origin and terroir are very important parameters for wine and significantly impact price. Incorrect declarations are known to occur intentionally to increase profit, thus, measures for control are required. Accompanying paperwork has been shown to be unreliable, thus, control of the product itself is required. Here we investigate and compare the stable isotope pattern of South African (Western Cape Province) wine, and evaluate its potential for discrimination from Central European/Austrian wine. The results show that the isotope values of the investigated South African wine samples differ significantly from the values of average Austrian (Central European) wines. Thus, a differentiation of the products from these two regions by stable isotope analysis is generally straightforward. However, the data suggest that vintages from years with exceptionally hot and dry summer weather in Europe may reduce the differentiation between these regions. Therefore, this method is a poten...
Microbial diversity in vineyards and in grapes has generated significant scientific interest. Fro... more Microbial diversity in vineyards and in grapes has generated significant scientific interest. From a biotechnological perspective, vineyard and grape biodiversity has been shown to impact soil, vine, and grape health and to determine the fermentation microbiome and the final character of wine. Thus, an understanding of the drivers that are responsible for the differences in vineyard and grape microbiota is required. The impact of soil and climate, as well as of viticultural practices in geographically delimited areas, have been reported. However, the limited scale makes the identification of generally applicable drivers of microbial biodiversity and of specific microbial fingerprints challenging. The comparison and meta-analysis of different datasets is furthermore complicated by differences in sampling and in methodology. Here we present data from a wide-ranging coordinated approach, using standardized sampling and data generation and analysis, involving four countries with differe...
Culture is an important factor that influences how marketing interacts with food choice. This stu... more Culture is an important factor that influences how marketing interacts with food choice. This study aims at exploring the effect of consumers’ Country of Origin (COO) on wine representations and perception using Chenin blanc as a model. The first objective was to evaluate the role of origin in the construction of the representation. We used the theoretical framework of social representation to compare South African (SA) and French consumers’ representations via a word association task. The results indicated that SA representations are dominated by consumers’ experience of the wine (sensory and emotional dimensions), whereas French representations are dominated by the wine itself, in particular its origin and mode of consumption. The second objective was to evaluate the effect of origin on wine categorization in two conditions: with and without information concerning the two geographical origins of the samples. Results showed that providing information on the origin of the wines affe...
Lipids are essential energy storage compounds and are the core structural elements of all biologi... more Lipids are essential energy storage compounds and are the core structural elements of all biological membranes. During wine alcoholic fermentation, the ability of yeasts to adjust the lipid composition of the plasma membrane partly determines their ability to cope with various fermentation-related stresses, including elevated levels of ethanol and the presence of weak acids. In addition, the lipid composition of grape juice also impacts the production of many wine-relevant aromatic compounds. Several studies have evaluated the impact of lipids and of their metabolism on fermentation performance and aroma production in the dominant wine yeastSaccharomyces cerevisiae, but limited information is available on other yeast species. Thus, the aim of this study was to evaluate the influence of specific fatty acid and sterol mixtures on various non-Saccharomycesyeast fermentation rates and the production of primary fermentation metabolites. The data show that the response to different lipid ...
Continuous cell-to-cell contact between different species is a general feature of all natural env... more Continuous cell-to-cell contact between different species is a general feature of all natural environments. However, almost all research is conducted on single-species cultures, reflecting a biotechnological bias and problems associated with the complexities of reproducibly growing and controlling multispecies systems. Consequently, biotic stress due to the presence of other species remains poorly understood. In this context, understanding the effects of physical contact between species when compared to metabolic contact alone is one of the first steps to unravelling the mechanisms that underpin microbial ecological interactions. The current technologies to study the effects of cell-to-cell contact present disadvantages, such as the inefficient or discontinuous exchange of metabolites when preventing contact between species. This paper presents and characterizes a novel bioreactor system that uses ceramic membranes to create a “multi-membrane” compartmentalized system whereby two or...
Journal of Industrial Microbiology and Biotechnology, 2020
Yeast and microalgae are microorganisms with widely diverging physiological and biotechnological ... more Yeast and microalgae are microorganisms with widely diverging physiological and biotechnological properties. Accordingly, their fields of applications diverge: yeasts are primarily applied in processes related to fermentation, while microalgae are used for the production of high-value metabolites and green technologies such as carbon capture. Heterotrophic–autotrophic systems and synthetic ecology approaches have been proposed as tools to achieve stable combinations of such evolutionarily unrelated species. We describe an entirely novel synthetic ecology-based approach to evolve co-operative behaviour between winery wastewater isolates of the yeast Saccharomyces cerevisiae and microalga Chlorella sorokiniana. The data show that biomass production and mutualistic growth improved when co-evolved yeast and microalgae strains were paired together. Combinations of co-evolved strains displayed a range of phenotypes, including differences in amino acid profiles. Taken together, the results...
Saccharomyces cerevisiae and Lactobacillus plantarum are responsible for alcoholic and malolactic... more Saccharomyces cerevisiae and Lactobacillus plantarum are responsible for alcoholic and malolactic fermentation, respectively. Successful completion of both fermentations is essential for many styles of wine, and an understanding of how these species interact with each other, as well as the development of compatible pairings of these species, will help to manage the process. However, targeted improvements of species interactions are difficult to perform, in part because of the chemical and biological complexity of natural grape juice. Synthetic ecological systems reduce this complexity and can overcome these difficulties. In such synthetic systems, mutualistic growth of different species can be enforced through the reciprocal exchange of essential nutrients. Here, we implemented a novel approach to evolve mutualistic traits by establishing a co-dependent relationship between S. cerevisiae BY4742Δthi4 and Lb. plantarum IWBT B038 by omitting different combinations of amino acids from a...
The increasingly large volumes of publicly available sensory descriptions of wine raises the ques... more The increasingly large volumes of publicly available sensory descriptions of wine raises the question whether this source of data can be mined to extract meaningful domain-specific information about the sensory properties of wine. We introduce a novel application of formal concept lattices, in combination with traditional statistical tests, to visualise the sensory attributes of a big data set of some 7,000 Chenin blanc and Sauvignon blanc wines. Complexity was identified as an important driver of style in hereto uncharacterised Chenin blanc, and the sensory cues for specific styles were identified. This is the first study to apply these methods for the purpose of identifying styles within varietal wines. More generally, our interactive data visualisation and mining driven approach opens up new investigations towards better understanding of the complex field of sensory science.
Spontaneous wine fermentation is characterized by yeast population evolution, modulated by comple... more Spontaneous wine fermentation is characterized by yeast population evolution, modulated by complex physical and metabolic interactions amongst various species. The contribution of any given species to the final wine character and aroma will depend on its numerical persistence during the fermentation process. Studies have primarily evaluated the effect of physical and chemical factors such as osmotic pressure, pH, temperature and nutrient availability on mono- or mixed-cultures comprising 2–3 species, but information about how interspecies ecological interactions in the wine fermentation ecosystem contribute to population dynamics remains scant. Therefore, in the current study, the effect of temperature and sulphur dioxide (SO2) on the dynamics of a multi-species yeast consortium was evaluated in three different matrices including synthetic grape juice, Chenin blanc and Grechetto bianco. The population dynamics were affected by temperature and SO2, reflecting differences in stress re...
ABSTRACTIn the macroscopic world, ecological interactions between multiple species of fauna and f... more ABSTRACTIn the macroscopic world, ecological interactions between multiple species of fauna and flora are recognised as major role-players in the evolution of any particular species. By comparison, research on ecological interactions as a driver of evolutionary adaptation in microbial ecosystems has been neglected. The evolutionary history of the budding yeast Saccharomyces cerevisiae has been extensively researched, providing an unmatched foundation for exploring adaptive evolution of microorganisms. However, in most studies, the habitat is only defined by physical and chemical parameters, and little attention is paid to the impact of cohabiting species. Such ecological interactions arguably provide a more relevant evolutionary framework. Within the genomic phylogenetic tree of S. cerevisiae strains, wine associated isolates form a distinct clade, also matched by phenotypic evidence. This domestication signature in genomes and phenomes suggests that the wine fermentation environmen...
Cells of the yeast Saccharomyces cerevisiae can undergo profound molecular, physiological and mor... more Cells of the yeast Saccharomyces cerevisiae can undergo profound molecular, physiological and morphological modifications in response to a limited supply of essential nutrients, in particular carbon or nitrogen sources. These include a shift in transcription patterns, the modification of the cell cycle, a change in budding pattern and strongly polarised growth. Cells having undergone these modifications do not separate after cell division is completed and form chains of elongated cells called pseudohyphae or filaments. Cells growing as filaments are able to invade agar plates and other substrates, a phenomenon referred to as invasive growth. A network of signal transduction pathways governs this switch from yeast-like growth to pseudohyphal and invasive growth. Important elements of this network have been identified, including nutrient signal-receptors, GTP-binding proteins, components of the pheromonedependent MAP kinase cascade, cAMP, and several transcription factors. In this review, we summarise our current knowledge in this rapidly progressing field. We focus particularly on the interactions between several signal transduction modules and on the different transcription factors, which are regulated by these signalling modules.
Geographic origin and terroir are very important parameters for wine and significantly impact pri... more Geographic origin and terroir are very important parameters for wine and significantly impact price. Incorrect declarations are known to occur intentionally to increase profit, thus, measures for control are required. Accompanying paperwork has been shown to be unreliable, thus, control of the product itself is required. Here we investigate and compare the stable isotope pattern of South African (Western Cape Province) wine, and evaluate its potential for discrimination from Central European/Austrian wine. The results show that the isotope values of the investigated South African wine samples differ significantly from the values of average Austrian (Central European) wines. Thus, a differentiation of the products from these two regions by stable isotope analysis is generally straightforward. However, the data suggest that vintages from years with exceptionally hot and dry summer weather in Europe may reduce the differentiation between these regions. Therefore, this method is a poten...
Microbial diversity in vineyards and in grapes has generated significant scientific interest. Fro... more Microbial diversity in vineyards and in grapes has generated significant scientific interest. From a biotechnological perspective, vineyard and grape biodiversity has been shown to impact soil, vine, and grape health and to determine the fermentation microbiome and the final character of wine. Thus, an understanding of the drivers that are responsible for the differences in vineyard and grape microbiota is required. The impact of soil and climate, as well as of viticultural practices in geographically delimited areas, have been reported. However, the limited scale makes the identification of generally applicable drivers of microbial biodiversity and of specific microbial fingerprints challenging. The comparison and meta-analysis of different datasets is furthermore complicated by differences in sampling and in methodology. Here we present data from a wide-ranging coordinated approach, using standardized sampling and data generation and analysis, involving four countries with differe...
Culture is an important factor that influences how marketing interacts with food choice. This stu... more Culture is an important factor that influences how marketing interacts with food choice. This study aims at exploring the effect of consumers’ Country of Origin (COO) on wine representations and perception using Chenin blanc as a model. The first objective was to evaluate the role of origin in the construction of the representation. We used the theoretical framework of social representation to compare South African (SA) and French consumers’ representations via a word association task. The results indicated that SA representations are dominated by consumers’ experience of the wine (sensory and emotional dimensions), whereas French representations are dominated by the wine itself, in particular its origin and mode of consumption. The second objective was to evaluate the effect of origin on wine categorization in two conditions: with and without information concerning the two geographical origins of the samples. Results showed that providing information on the origin of the wines affe...
Lipids are essential energy storage compounds and are the core structural elements of all biologi... more Lipids are essential energy storage compounds and are the core structural elements of all biological membranes. During wine alcoholic fermentation, the ability of yeasts to adjust the lipid composition of the plasma membrane partly determines their ability to cope with various fermentation-related stresses, including elevated levels of ethanol and the presence of weak acids. In addition, the lipid composition of grape juice also impacts the production of many wine-relevant aromatic compounds. Several studies have evaluated the impact of lipids and of their metabolism on fermentation performance and aroma production in the dominant wine yeastSaccharomyces cerevisiae, but limited information is available on other yeast species. Thus, the aim of this study was to evaluate the influence of specific fatty acid and sterol mixtures on various non-Saccharomycesyeast fermentation rates and the production of primary fermentation metabolites. The data show that the response to different lipid ...
Continuous cell-to-cell contact between different species is a general feature of all natural env... more Continuous cell-to-cell contact between different species is a general feature of all natural environments. However, almost all research is conducted on single-species cultures, reflecting a biotechnological bias and problems associated with the complexities of reproducibly growing and controlling multispecies systems. Consequently, biotic stress due to the presence of other species remains poorly understood. In this context, understanding the effects of physical contact between species when compared to metabolic contact alone is one of the first steps to unravelling the mechanisms that underpin microbial ecological interactions. The current technologies to study the effects of cell-to-cell contact present disadvantages, such as the inefficient or discontinuous exchange of metabolites when preventing contact between species. This paper presents and characterizes a novel bioreactor system that uses ceramic membranes to create a “multi-membrane” compartmentalized system whereby two or...
Journal of Industrial Microbiology and Biotechnology, 2020
Yeast and microalgae are microorganisms with widely diverging physiological and biotechnological ... more Yeast and microalgae are microorganisms with widely diverging physiological and biotechnological properties. Accordingly, their fields of applications diverge: yeasts are primarily applied in processes related to fermentation, while microalgae are used for the production of high-value metabolites and green technologies such as carbon capture. Heterotrophic–autotrophic systems and synthetic ecology approaches have been proposed as tools to achieve stable combinations of such evolutionarily unrelated species. We describe an entirely novel synthetic ecology-based approach to evolve co-operative behaviour between winery wastewater isolates of the yeast Saccharomyces cerevisiae and microalga Chlorella sorokiniana. The data show that biomass production and mutualistic growth improved when co-evolved yeast and microalgae strains were paired together. Combinations of co-evolved strains displayed a range of phenotypes, including differences in amino acid profiles. Taken together, the results...
Saccharomyces cerevisiae and Lactobacillus plantarum are responsible for alcoholic and malolactic... more Saccharomyces cerevisiae and Lactobacillus plantarum are responsible for alcoholic and malolactic fermentation, respectively. Successful completion of both fermentations is essential for many styles of wine, and an understanding of how these species interact with each other, as well as the development of compatible pairings of these species, will help to manage the process. However, targeted improvements of species interactions are difficult to perform, in part because of the chemical and biological complexity of natural grape juice. Synthetic ecological systems reduce this complexity and can overcome these difficulties. In such synthetic systems, mutualistic growth of different species can be enforced through the reciprocal exchange of essential nutrients. Here, we implemented a novel approach to evolve mutualistic traits by establishing a co-dependent relationship between S. cerevisiae BY4742Δthi4 and Lb. plantarum IWBT B038 by omitting different combinations of amino acids from a...
The increasingly large volumes of publicly available sensory descriptions of wine raises the ques... more The increasingly large volumes of publicly available sensory descriptions of wine raises the question whether this source of data can be mined to extract meaningful domain-specific information about the sensory properties of wine. We introduce a novel application of formal concept lattices, in combination with traditional statistical tests, to visualise the sensory attributes of a big data set of some 7,000 Chenin blanc and Sauvignon blanc wines. Complexity was identified as an important driver of style in hereto uncharacterised Chenin blanc, and the sensory cues for specific styles were identified. This is the first study to apply these methods for the purpose of identifying styles within varietal wines. More generally, our interactive data visualisation and mining driven approach opens up new investigations towards better understanding of the complex field of sensory science.
Spontaneous wine fermentation is characterized by yeast population evolution, modulated by comple... more Spontaneous wine fermentation is characterized by yeast population evolution, modulated by complex physical and metabolic interactions amongst various species. The contribution of any given species to the final wine character and aroma will depend on its numerical persistence during the fermentation process. Studies have primarily evaluated the effect of physical and chemical factors such as osmotic pressure, pH, temperature and nutrient availability on mono- or mixed-cultures comprising 2–3 species, but information about how interspecies ecological interactions in the wine fermentation ecosystem contribute to population dynamics remains scant. Therefore, in the current study, the effect of temperature and sulphur dioxide (SO2) on the dynamics of a multi-species yeast consortium was evaluated in three different matrices including synthetic grape juice, Chenin blanc and Grechetto bianco. The population dynamics were affected by temperature and SO2, reflecting differences in stress re...
ABSTRACTIn the macroscopic world, ecological interactions between multiple species of fauna and f... more ABSTRACTIn the macroscopic world, ecological interactions between multiple species of fauna and flora are recognised as major role-players in the evolution of any particular species. By comparison, research on ecological interactions as a driver of evolutionary adaptation in microbial ecosystems has been neglected. The evolutionary history of the budding yeast Saccharomyces cerevisiae has been extensively researched, providing an unmatched foundation for exploring adaptive evolution of microorganisms. However, in most studies, the habitat is only defined by physical and chemical parameters, and little attention is paid to the impact of cohabiting species. Such ecological interactions arguably provide a more relevant evolutionary framework. Within the genomic phylogenetic tree of S. cerevisiae strains, wine associated isolates form a distinct clade, also matched by phenotypic evidence. This domestication signature in genomes and phenomes suggests that the wine fermentation environmen...
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