Enhancement of pyranoanthocyanin formation in blueberry wine with non-Saccharomyces yeasts.

The development of blueberry wine provides an alternative method for maintaining the nutritional value and extending the shelf life of blueberries. However, anthocyanin loss and off-flavor compound generation during fermentation impair blueberry wine color and quality. Hydroxycinnamate decarboxylase from yeast can catalyze the conversion of hydroxycinnamic acids to vinylphenols, which later may condense with anthocyanins to form more stable vinylphenolic pyranoanthocyanins.

Non-Saccharomyces yeasts for beer production: Insights into safety aspects and considerations.

The application of non-Saccharomyces yeasts in beer as a natural tool for innovation, to create different aroma profiles and flavoured non-alcoholic beers, has attracted great interest from both researchers and commercial brewers. As a result, a higher diversity of non-Saccharomyces yeasts for beer production is expected on the market in the coming years. However, the safe use of non-Saccharomyces yeasts has not been broadly investigated and no guidance for the safety assessment of yeasts is published.

Enzymatic modification and adsorption of hydrophobic zein proteins on lactic acid bacteria stabilize Pickering emulsions.

The effect of enzymatic and physical modifications of the surface of two different strains from lactic acid bacteria, Lactobacillus rhamnosus (LGG) and Lactobacillus delbruekii subs. lactis ATCC 4797 (LBD), to stabilize medium-chain triglyceride (MCT) oil based Pickering emulsions were investigated. A section of cell wall degrading enzymes, lysozyme from chicken egg white and human, lysostaphin, mutanolysin from Streptomyces globisporus and proteinase k and the hydrophobic protein zein were used for enzymatic and physical surface modifications.

Saccharomyces cerevisiae does not undergo a quorum sensing-dependent switch of budding pattern.

Saccharomyces cerevisiae can alter its morphology to a filamentous form associated with unipolar budding in response to environmental stressors. Induction of filamentous growth is suggested under nitrogen deficiency in response to alcoholic signalling molecules through quorum sensing. To investigate this further, we analysed the budding pattern of S.

Multi-species colloidosomes by surface-modified lactic acid bacteria with enhanced aggregation properties.

Hypothesis: Surface modification of lactic acid bacteria enhances their adsorption and aggregation at air-water interface and enables stabilization of microbubbles that spontaneously transform into water-filled colloidosomes, which can be further modified using LBL formulations.

Experiments: The bacterial physicochemical properties were characterized using water contact angle (WCA) measurement, bacterial aggregation assay and zeta potential measurement. Cell viability was enumerated using plate-counting method.

Reliable budding pattern classification of yeast cells with time-resolved measurement of metabolite production.

Filamentous growth in is a stress response commonly induced under nutrient deprivation and by certain alcohols. It is a compound phenotype characterized by pseudohyphal growth, invasion and a shift to more polarized budding. Previous methods have not allowed the time-resolved determination of filamentous growth.

Efficient chemical hydrophobization of lactic acid bacteria - One-step formation of double emulsion.

A novel concept of stabilizing multiple-phase food structure such as emulsion using solely the constitutional bacteria enables an all-natural food grade formulation and thus a clean label declaration. In this paper, we propose an efficient approach to hydrophobically modifying the surface of lactic acid bacteria Lactobacillus rhamnosus (LGG) using lauroyl ahloride (LC) in non-aqueous media. Compared to the unmodified bacteria, cell hydrophobicity was dramatically altered upon modification, according to the higher percentages of microbial adhesion to hexadecane (MATH) and water contact angles (WCA) of LC-modified bacteria.

Strains Isolated From Danish Cheese Brines Act as Biocontrol Agents to Inhibit Germination and Growth of Contaminating Molds.

The antagonistic activities of native strains isolated from Danish cheese brines were evaluated against contaminating molds in the dairy industry. Determination of chromosome polymorphism by use of pulsed-field gel electrophoresis (PFGE) revealed a huge genetic heterogeneity among the strains, which was reflected in intra-species variation at the phenotypic level. 11 strains were tested for their ability to inhibit germination and growth of contaminating molds, frequently occurring at Danish dairies, i.

Analysis of the response of the cell membrane of Saccharomyces cerevisiae during the detoxification of common lignocellulosic inhibitors.

Gaining an in-depth understanding of the response of Saccharomyces cerevisiae to the different inhibitors generated during the pretreatment of lignocellulosic material is driving the development of new strains with higher inhibitor tolerances. The objective of this study is to assess, using flow cytometry, how three common inhibitors (vanillin, furfural, and acetic acid) affect the membrane potential, the membrane permeability and the concentration of reactive oxygen species (ROS) during the different fermentations. The membrane potential decreased during the detoxification phase and reflected on the different mechanisms of the toxicity of the inhibitors.

The Effects of NaCl and Temperature on Growth and Survival of Yeast Strains Isolated from Danish Cheese Brines.

Yeasts play an important role in cheese making, by contributing to microbial community establishment and improving flavor. This study aimed at investigating the impact of NaCl and temperature on growth and survival of 20 strains belonging to the yeast species Candida intermedia (2 strains), Debaryomyces hansenii (11), Kluyveromyces lactis (1), Papiliotrema flavescens (1), Rhodotorula glutinis (1), Sterigmatomyces halophilus (2) and Yamadazyma triangularis (2) isolated from Danish cheese brines. All yeasts could grow in Malt Yeast Glucose Peptone (MYGP) medium with low NaCl (≤ 4%, w/v) concentrations at 25 °C and 16 °C.

Fast measurement of phosphates and ammonium in fermentation-like media: A feasibility study.

Real-time monitoring of bioprocesses plays a key-role in modern industries, providing new information on full-scale production, thus enabling control of the process and allowing it to run at optimal conditions while minimizing waste. Monitoring of phosphates and ammonium in fermentation processes has a twofold interest: they are important nutrients for living organisms while at the same time constituting environmental nutrient pollutants, for which unnecessary use and disposal must be avoided. In this report, the possibility of simultaneous analysis of phosphates and ammonium in fermentations was verified using spectroscopy-based methods combined with chemometrics to construct calibration models.

Proteomics insights into the responses of Saccharomyces cerevisiae during mixed-culture alcoholic fermentation with Lachancea thermotolerans.

The response of Saccharomyces cerevisiae to cocultivation with Lachancea thermotolerans during alcoholic fermentations has been investigated using tandem mass tag (TMT)-based proteomics. At two key time-points, S. cerevisiae was sorted from single S.

Can community-based signalling behaviour in Saccharomyces cerevisiae be called quorum sensing? A critical review of the literature.

Quorum sensing is a well-described mechanism of intercellular signalling among bacteria, which involves cell-density-dependent chemical signal molecules. The concentration of these quorum-sensing molecules increases in proportion to cell density until a threshold value is exceeded, which triggers a community-wide response. In this review, we propose that intercellular signalling mechanisms can be associated with a corresponding ecological interaction type based on similarities between how the interaction affects the signal receiver and producer.

Metabolic footprint analysis of metabolites that discriminate single and mixed yeast cultures at two key time-points during mixed culture alcoholic fermentations.

Introduction: There has been a growing interest towards creating defined mixed starter cultures for alcoholic fermentations. Previously, metabolite differences between single and mixed cultures have been explored at the endpoint of fermentations rather than during fermentations.

Objectives: To create metabolic footprints of metabolites that discriminate single and mixed yeast cultures at two key time-points during mixed culture alcoholic fermentations.

Cheese brines from Danish dairies reveal a complex microbiota comprising several halotolerant bacteria and yeasts.

The Danish Danbo cheese is a surface ripened semi-hard cheese, which before ripening is submerged in brine for up to 24 h. The brining is required in order to obtain the structural and organoleptic properties of the cheeses. Likewise, the content of NaCl in the cheese will influence especially the surface microbiota being of significant importance for flavour development and prevention of microbial spoilage.

Occurrence of lactic acid bacteria and yeasts at species and strain level during spontaneous fermentation of mawè, a cereal dough produced in West Africa.

Mawè is a West African spontaneous fermented cereal-based dough. Different types of mawè exist varying in type of cereal and/or production condition, with fermentations lasting 24-48 h. With the aim of obtaining a comprehensive understanding of the microbial ecology of mawè processing, a microbiological characterisation was performed for four mawè types, produced at eight sites in Benin.

Effect of GAPDH-derived antimicrobial peptides on sensitive yeasts cells: membrane permeability, intracellular pH and H+-influx/-efflux rates.

Saccharomyces cerevisiae secretes antimicrobial peptides (AMPs) derived from glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which induce the death of several non-Saccharomyces yeasts. Previously, we demonstrated that the naturally secreted GAPDH-derived AMPs (i.e.

Saccharomyces cerevisiae accumulates GAPDH-derived peptides on its cell surface that induce death of non-Saccharomyces yeasts by cell-to-cell contact.

During wine fermentations, Saccharomyces cerevisiae starts to excrete antimicrobial peptides (AMPs) into the growth medium that induce death of non-Saccharomyces yeasts at the end of exponential growth phase (24-48 h). Those AMPs were found to derive from the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). On the other hand, the early death of non-Saccharomyces yeasts during wine fermentations was also found to be mediated by a cell-to-cell contact mechanism.

Effect of sequential fermentations and grape cultivars on volatile compounds and sensory profiles of Danish wines.

Background: There has been an increasing interest in the use of selected non-Saccharomyces yeasts in co-culture with Saccharomyces cerevisiae. In this work, three non-Saccharomyces yeast strains (Metschnikowia viticola, Metschnikowia fructicola and Hanseniaspora uvarum) indigenously isolated in Denmark were used in sequential fermentations with S. cerevisiae on three cool-climate grape cultivars, Bolero, Rondo and Regent.

Antimicrobial properties and death-inducing mechanisms of saccharomycin, a biocide secreted by Saccharomyces cerevisiae.

We recently found that Saccharomyces cerevisiae (strain CCMI 885) secretes antimicrobial peptides (AMPs) derived from the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH) that are active against various wine-related yeast and bacteria. Here, we show that several other S. cerevisiae strains also secrete natural biocide fractions during alcoholic fermentation, although at different levels, which correlates with the antagonistic effect exerted against non-Saccharomyces yeasts.

Influence of extracellular pH on growth, viability, cell size, acidification activity, and intracellular pH of Lactococcus lactis in batch fermentations.

In this study, we investigated the influence of three extracellular pH (pHex) values (i.e., 5.

Dominance of Saccharomyces cerevisiae in alcoholic fermentation processes: role of physiological fitness and microbial interactions.

Winemaking, brewing and baking are some of the oldest biotechnological processes. In all of them, alcoholic fermentation is the main biotransformation and Saccharomyces cerevisiae the primary microorganism. Although a wide variety of microbial species may participate in alcoholic fermentation and contribute to the sensory properties of end-products, the yeast S.