Killer Toxins of Yeasts: Inhibitors of Fermentation and Their Adsorption

1987 ◽  
Vol 50 (3) ◽  
pp. 234-238 ◽  
Author(s):  
FERDINAND RADLER ◽  
MANFRED SCHMITT
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Yeast Cell ◽  
Cell Walls ◽  
Killer Toxin ◽  
Yeast Cells ◽  
Toxin Concentration ◽  
Commercial Preparation ◽  
Killer Toxins ◽  
Original Amount

The killer toxin (KT 28), a glycoprotein of Saccharomyces cerevisiae strain 28, was almost completely adsorbed by bentonite, when applied at a concentration of 1 g per liter. No significant differences were found between several types of bentonite. Killer toxin KT 28 is similarly adsorbed by intact yeast cells or by a commercial preparation of yeast cell walls that has been recommended to prevent stuck fermentations. An investigation of the cell wall fractions revealed that the toxin KT 28 was mainly adsorbed by mannan, that removed the toxin completely. The alkali-soluble and the alkali-insoluble β-1,3- and β-1,6-D-glucans lowered the toxin concentration to one tenth of the original amount. The killer toxin of the type K1 of S. cerevisiae was adsorbed much better by glucans than by mannan.

scholarly journals Cell fusion in yeast is negatively regulated by components of the cell wall integrity pathway

2019 ◽  
Vol 30 (4) ◽  
pp. 441-452 ◽  
Author(s):  
Allison E. Hall ◽  
Mark D. Rose
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Death ◽  
Cell Wall ◽  
Yeast Cell ◽  
Cell Fusion ◽  
Cell Walls ◽  
Cell Wall Integrity ◽  
Fusion Genes ◽  
Cell Wall Degradation ◽  
Cell Wall Integrity Pathway

During mating, Saccharomyces cerevisiae cells must degrade the intervening cell wall to allow fusion of the partners. Because improper timing or location of cell wall degradation would cause lysis, the initiation of cell fusion must be highly regulated. Here, we find that yeast cell fusion is negatively regulated by components of the cell wall integrity (CWI) pathway. Loss of the cell wall sensor, MID2, specifically causes “mating-induced death” after pheromone exposure. Mating-induced death is suppressed by mutations in cell fusion genes ( FUS1, FUS2, RVS161, CDC42), implying that mid2Δ cells die from premature fusion without a partner. Consistent with premature fusion, mid2Δ shmoos had thinner cell walls and lysed at the shmoo tip. Normally, Cdc42p colocalizes with Fus2p to form a focus only when mating cells are in contact (prezygotes) and colocalization is required for cell fusion. However, Cdc42p was aberrantly colocalized with Fus2p to form a focus in mid2Δ shmoos. A hyperactive allele of the CWI kinase Pkc1p ( PKC1*) caused decreased cell fusion and Cdc42p localization in prezygotes. In shmoos, PKC1* increased Cdc42p localization; however, it was not colocalized with Fus2p or associated with cell death. We conclude that Mid2p and Pkc1p negatively regulate cell fusion via Cdc42p and Fus2p.

scholarly journals Two Novel Techniques for Determination of Polysaccharide Cross-Links Show that Crh1p and Crh2p Attach Chitin to both β(1-6)- and β(1-3)Glucan in the Saccharomyces cerevisiae Cell Wall

2009 ◽  
Vol 8 (11) ◽  
pp. 1626-1636 ◽  
Author(s):  
Enrico Cabib
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Acetic Acid ◽  
Yeast Cell ◽  
Cell Walls ◽  
Double Mutant ◽  
The Other ◽  
Cross Links

ABSTRACT Previous work, using solubilization of yeast cell walls by carboxymethylation, before or after digestion with β(1-3)- or β(1-6)glucanase, followed by size chromatography, showed that the transglycosylases Crh1p and Crh2p/Utr2p were redundantly required for the attachment of chitin to β(1-6)glucan. With this technique, crh1Δ crh2Δ mutants still appeared to contain a substantial percentage of chitin linked to β(1-3)glucan. Two novel procedures have now been developed for the analysis of polysaccharide cross-links in the cell wall. One is based on the affinity of curdlan, a β(1-3)glucan, for β(1-3)glucan chains in carboxymethylated cell walls. The other consists of in situ deacetylation of cell wall chitin, generating chitosan, which can be extracted with acetic acid, either directly (free chitosan) or after digestion with different glucanases (bound chitosan). Both methodologies indicated that all of the chitin in crh1Δ crh2Δ strains is free. Reexamination of the previously used procedure revealed that the β(1-3)glucanase preparation used (zymolyase) is contaminated with a small amount of endochitinase, which caused erroneous results with the double mutant. After removing the chitinase from the zymolyase, all three procedures gave coincident results. Therefore, Crh1p and Crh2p catalyze the transfer of chitin to both β(1-3)- and β(1-6)glucan, and the biosynthetic mechanism for all chitin cross-links in the cell wall has been established.

scholarly journals Significant quantities of the glycolytic enzyme phosphoglycerate mutase are present in the cell wall of yeast Saccharomyces cerevisiae

2003 ◽  
Vol 369 (2) ◽  
pp. 357-362 ◽  
Author(s):  
Precious MOTSHWENE ◽  
Wolf BRANDT ◽  
George LINDSEY
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Cell Walls ◽  
Glycolytic Enzyme ◽  
Yeast Cells ◽  
Phosphoglycerate Mutase ◽  
Elevated Concentration ◽  
Yeast Saccharomyces Cerevisiae ◽  
Normal Morphology ◽  
Immunocytochemical Analysis

NaOH was used to extract proteins from the cell walls of the yeast Saccharomyces cerevisiae. This treatment was shown not to disrupt yeast cells, as NaOH-extracted cells displayed a normal morphology upon electron microscopy. Moreover, extracted and untreated cells had qualitatively similar protein contents upon disruption. When yeast was grown in the presence of 1M mannitol, two proteins were found to be present at an elevated concentration in the cell wall. These were found to be the late-embryogenic-abundant-like protein heat-shock protein 12 and the glycolytic enzyme phosphoglycerate mutase. The presence of phosphoglycerate mutase in the cell wall was confirmed by immunocytochemical analysis. Not only was the phosphoglycerate mutase in the yeast cell wall found to be active, but whole yeast cells were also able to convert 3-phosphoglycerate in the medium into ethanol, provided that the necessary cofactors were present.

Adsorption of Zearalenone by β-d-Glucans in the Saccharomyces cerevisiae Cell Wall

2004 ◽  
Vol 67 (6) ◽  
pp. 1195-1200 ◽  
Author(s):  
A. YIANNIKOURIS ◽  
J. FRANÇOIS ◽  
L. POUGHON ◽  
C.-G. DUSSAP ◽  
G. BERTIN ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Complex Formation ◽  
Yeast Cell ◽  
Cell Walls ◽  
Chemical Interaction ◽  
Feed Additives ◽  
Dimensional Structure ◽  
Chitin Content

Cell walls of yeasts and bacteria are able to complex with mycotoxins and limit their bioavailability in the digestive tract when these yeasts and bacteria are given as feed additives to animals. To identify the component(s) of the yeast cell wall and the chemical interaction(s) involved in complex formation with zearalenone, four strains of Saccharomyces cerevisiae differing in their cell wall glucan and mannan content were tested. Laboratory strains wt292, fks1, and mnn9 were compared with industrial S. cerevisiae strain sc1026. The complex-forming capacity of the yeast cell walls was determined in vitro by modelling the plots of amount of toxin bound versus amount of toxin added using Hill's model. A cooperative relationship between toxin and adsorbent was shown, and a correlation between the amount of β-d-glucans in cell walls and complex-forming efficacy was revealed (R2 = 0.889). Cell walls of strains wt292 and mnn9, which have higher levels of β-d-glucans, were able to complex larger amounts of zearalenone, with higher association constants and higher affinity rates than those of the fks1 and sc1026 strains. The high chitin content in strains mnn9 and fks1 increased the alkali insolubility of β-d-glucans from isolated cell walls and decreased the flexibility of these cell walls, which restricted access of zearalenone to the chemical sites of the β-d-glucans involved in complex formation. The strains with high chitin content thus had a lower complex-forming capacity than expected based on their β-d-glucans content. Cooperativity and the three-dimensional structure of β-d-glucans indicate that weak noncovalent bonds are involved in the complex-forming mechanisms associated with zearalenone. The chemical interactions between β-d-glucans and zearalenone are therefore more of an adsorption type than a binding type.

L'hydrolyse des hétérosides terpéniques du Muscat a petits grains par les enzymes périplasmiques de Saccharomyces cerevisiae

OENO One ◽  
1988 ◽  
Vol 22 (3) ◽  
pp. 189 ◽  
Author(s):  
Philippe Darriet ◽  
Jean-Noël Boidron ◽  
Denis Dubourdieu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Yeast Cell ◽  
Cell Walls ◽  
Yeast Cells ◽  
Periplasmic Space ◽  
Enzymatic Extract ◽  
Periplasmic Extract ◽  
Glucosidase Activity ◽  
Aroma Precursors ◽  
Hydrolysis Of

<p style="text-align: justify;">Osidases located in periplasmic space of <em>Saccharomyces cerevisiae</em> are able to hydrolyse monoterpenes heterosides of Muscat grapes. To prepare the periplasmic extract, yeast cell walls are digested with <em>Zymolyase</em> in the presence of an osmotic protector to prevent lysis of the resulting protoplasts; periplasmic enzymes are liberated into the supernatant medium. Monoterpenes heterosides are incubated 48 or 72 hours at 25° C with either intact yeast cells or periplasmic enzymatic extract. Monoterpenes, especially gerianol and nerol, are liberated in these conditions. β-glucosidase activity seems to play an important rôle in these reactions.</p><p style="text-align: justify;">Fungal extracellular β-glucosidases are commonly strongly inhibited by glucose. Surprisingly, the activity of periplasmic yeast β-glucosidase is quite glucose independant. These results suggest that some periplasmic enzymes from yeast may be involved in the hydrolysis of varietal aroma precursors in wines.</p>

scholarly journals ENCAPSULATION OF LACTOBACILLUS ACIDOPHILUS IN YEAST CELL WALLS (SACCHAROMYCES CEREVISIAE) FOR IMPROVING SURVIVAL IN GASTROINTESTINAL CONDITIONS

2016 ◽  
Vol 54 (4) ◽  
pp. 533
Author(s):  
Le Nguyen Han ◽  
Le Huynh Hong Van ◽  
Tran Van Duc ◽  
Dong Thi Anh Dao
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Yeast Cell ◽  
Cell Walls ◽  
Free Cell ◽  
Yeast Cells ◽  
Extreme Condition ◽  
Cell Contact ◽  
Health Products ◽  
Quality Health ◽  
Direct Cell

In search of high-quality health products, it is required that probiotic preparations consumed in gastro-intestinal condition remain metabolically active and preserve their activity. Several recent studies, consequently, have focused on probiotic protection via encapsulation in order to optimize probiotics’ viability as well as their delivery into gastro-intestinal environment. The objectives of this study were to find out a new material for encapsulation of probiotics, utilizing capsules prepared from Saccharomyces cerevisiae to protect living probiotic cells. The encapsulation of cells was achieved, using the crack scars of the yeast cell walls (YCW) created by the sonication method. Besides, some probiotic cells can be considered as being encapsulated by some surrounded yeast cells by direct cell-cell contact. It is concluded that thanks to encapsulation by yeast cells, probiotic’s metabolic activity and survival are markedly improved. This suggests a high potential in protecting probiotics from the extreme condition of digestion process and can be applied in protecting probiotic preparations in food formulations as well. It was found that encapsulation yield in this study reached its highest point at 82.008 ± 1.123%. Viability of encapsulated probiotic in simulated gastric juice (SGJ) after 150 minutes is 19.048 ± 2.701%, compared to that of free cells at 0%. Likewise, after a 4-hour treatment in simulated intestinal juice (SIJ) (0.5% bile salt) encapsulated probiotic proves better survival at 56.338 ± 5.094% than free cell at 43.677 ± 2.058%.

scholarly journals Bioaccessibility of curcumin encapsulated in yeast cells and yeast cell wall particles

2020 ◽  
Vol 309 ◽  
pp. 125700 ◽  
Author(s):  
Stephen Young ◽  
Rewa Rai ◽  
Nitin Nitin
Keyword(s):  
Cell Wall ◽  
Yeast Cell ◽  
Yeast Cells ◽  
Yeast Cell Wall

scholarly journals Interactions of Surfactant Proteins A and D with Saccharomyces cerevisiae and Aspergillus fumigatus

2001 ◽  
Vol 69 (4) ◽  
pp. 2037-2044 ◽  
Author(s):  
Martin J. Allen ◽  
Dennis R. Voelker ◽  
Robert J. Mason
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Aspergillus Fumigatus ◽  
Cell Walls ◽  
Specific Interaction ◽  
Surfactant Proteins ◽  
Yeast Cells ◽  
Calcium Dependent ◽  
Before And After ◽  
Carbohydrate Polymer ◽  
Defense Molecules

ABSTRACT Surfactant proteins A (SP-A) and D (SP-D) are members of the collectin family of calcium-dependent lectins and are important pulmonary host defense molecules. Human SP-A and SP-D and rat SP-D bind to Aspergillus fumigatus conidia, but the ligand remains unidentified. To identify a fungal ligand for SP-A and/or SP-D, we examined the interactions of the proteins with Saccharomyces cerevisiae. SP-D but not SP-A bound yeast cells, and EDTA inhibited the binding. SP-D also aggregated yeast cells and isolated yeast cell walls. Treating yeast cells to remove cell wall mannoprotein did not reduce SP-D binding, and SP-D failed to aggregate chitin. However, SP-D aggregated yeast glucan before and after treatment with a β(1→3)-glucanase, suggesting a specific interaction between the collectin and β(1→6)-glucan. In support of this idea, SP-D-induced yeast aggregation was strongly inhibited by pustulan [a β(1→6)-linked glucose homopolymer] but was not inhibited by laminarin [a β(1→3)-linked glucose homopolymer]. Additionally, pustulan but not laminarin strongly inhibited SP-D binding to A. fumigatus. The pustulan concentration for 50% inhibition of SP-D binding to A. fumigatus is 1.0 ± 0.3 μM glucose equivalents. Finally, SP-D showed reduced binding to the β(1→6)-glucan-deficient kre6 yeast mutant. Taken together, these observations demonstrate that β(1→6)-glucan is an important fungal ligand for SP-D and that glycosidic bond patterns alone can determine if an extended carbohydrate polymer is recognized by SP-D.

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