Search results for "yeast"

Drying enhances immunoactivity of spent brewer's yeast cell wall β-D-glucans.

2015

Due to immunological activity, microbial cell wall polysaccharides are defined as 'biological response modifiers' (BRM). Cell walls of spent brewer's yeast also have some BRM activity. However, up to date there is no consensus on the use of spent brewer's yeast D-glucan as specific BRM in humans or animals. The aim of this paper is to demonstrate the potential of spent brewer's yeast β-D-glucans as BRM, and drying as an efficient pretreatment to increase β-D-glucan's immunogenic activity. Our results revealed that drying does not change spent brewer's yeast biomass carbohydrate content as well as the chemical structure of purified β-D-glucan. However, drying increased purified β-D-glucan TN…

Influence of autochthonous microbiota on the sicilian wine producution

2014

Transglutaminase activity is involved in Saccharomyces cerevisiae wall construction

2002

Transglutaminase activity, which forms the interpeptidic cross-link N(epsilon)-(gamma-glutamyl)-lysine, was demonstrated in cell-free extracts of Saccharomyces cerevisiae by incorporation of [(14)C]lysine into an exogenous acceptor, N,N'-dimethylcasein. Higher levels of the activity were present in the cell wall, which also contained endogenous acceptors. The enzyme activity in the wall was inhibited by cystamine, a known inhibitor of transglutaminase, and by EDTA, indicating a cation-dependent activity. After the endogenous wall acceptors were labelled radioactively by transglutaminase, extraction with SDS solubilized about 50% of the total radioactivity, while Zymolyase and chitinase each…

Fluorescent probes to evaluate the physiological state and activity of microbial biocatalysts: A guide for prokaryotic and eukaryotic investigation

2008

International audience; Many fluorescent techniques are employed to evaluate the viability and activity of microbial cells used in biotechnology. These techniques are sometimes complex and the interpretation of results opened to misunderstanding. Moreover, new developments are constantly proposed especially concerning a more accurate evaluation of the state of the cells including eukaryotic microorganisms. This paper aims at presenting to biotechnologists unfamiliar with fluorescence the principles of these methods and the related possible pitfalls. It focuses on probes of the physical (integrity and fluidity) and energetical (intracellular pH and membrane potential) state of the cell membr…

The glucose-dependent transport of L-malate in Zygosaccharomyces bailii.

1984

Zygosaccharomyces bailii possesses a constitutive malic enzyme, but only small amounts of malate are decomposed when the cells ferment fructose. Cells growing anaerobically on glucose (glucose cells) decompose malate, whereas fructose cells do not. Only glucose cells show an increase in the intracellular concentration of malate when suspended in a malate-containing solution. The transport system for malate is induced by glucose, but it is repressed by fructose. The synthesis of this transport system is inhibited by cycloheximide. Of the two enantiomers L-malate is transported preferentially. The transport of malate by induced cells is not only inhibited by addition of fructose but also inac…

Assessing Chronological Aging in Saccharomyces cerevisiae

2012

Saccharomyces cerevisiae is one of the most studied model organisms for the identification of genes and mechanisms that affect aging. The chronological lifespan (CLS) assay, which monitors the survival of a non-dividing population, is one of the two methods to study aging in yeast. To eliminate potential artifacts and identify genes and signaling pathways that may also affect aging in higher eukaryotes, it is important to determine CLS by multiple methods. Here, we describe these methods as well as the assays to study macromolecular damage during aging in yeast, with a focus on genomic instability.

Acetic acid and acidification accelerate chronological and replicative aging in yeast

2012

Yeast is widely regarded as one of the most valuable model systems to study aging and particularly the genetics of aging. Researchers have established two different methods to study yeast aging known as the replicative lifespan (RLS) and the chronological lifespan (CLS). These have led to the identification of many mammalian genes that affect aging suggesting that they will continue to shed light on the fundamental biology of aging. In spite of the clear differences underpinning the mitotic cellular potential (RLS) and the survival in the non-dividing mode (CLS), the two models are clearly regulated by partly overlapping regulatory mechanism. This idea is supported by the observation that c…

EngineeredControl of Cell Morphology In Vivo Reveals Distinct Roles for Yeast andFilamentous Forms of Candida albicans duringInfection

2003

ABSTRACT It is widely assumed that the ability of Candida albicans to switch between different morphologies is required for pathogenesis. However, most virulence studies have used mutants that are permanently locked into either the yeast or filamentous forms which are avirulent but unsuitable for discerning the role of morphogenetic conversions at the various stages of the infectious process. We have constructed a strain in which this developmental transition can be externally modulated both in vitro and in vivo. This was achieved by placing one copy of the NRG1 gene (a negative regulator of filamentation) under the control of a tetracycline-regulatable promoter. This modified strain was th…

Adenine auxotrophy--be aware: some effects of adenine auxotrophy in Saccharomyces cerevisiae strain W303-1A.

2013

Adenine auxotrophy is a commonly used genetic marker in haploid yeast strains. Strain W303-1A, which carries the ade2-1 mutation, is widely used in physiological and genetic research. Yeast extract-based rich medium contains a low level of adenine, so that adenine is often depleted before glucose. This could affect the cell physiology of adenine auxotrophs grown in rich medium. The aim of our study was to assess the effects of adenine auxotrophy on cell morphology and stress physiology. Our results show that adenine depletion halts cell division, but that culture optical density continues to increase due to cell swelling. Accumulation of trehalose and a coincident 10-fold increase in desicc…

Autolysis of Yeasts

2011

Autolysis of yeast cells occurs after they have completed their life cycle and entered the death phase. It is characterized by a loss of cell membrane permeability, alteration of cell wall porosity, hydrolysis of cellular macromolecules by endogenous enzymes, and subsequent leakage of the breakdown products into the extracellular environment. Although a naturally occurring event, autolysis can be induced by exposing yeasts to elevated temperatures (40–60 °C), organic solvents, or detergents. Yeast autolysis occurs in many foods and beverages, where it may affect their sensory quality and commercial acceptability.