scholarly journals Flocculation onset, growth phase, and genealogical age in Saccharomyces cerevisiae

1996 ◽  
Vol 42 (6) ◽  
pp. 539-547 ◽  
Author(s):  
Eduardo V. Soares ◽  
Manuel Mota
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Culture Medium ◽  
Brewing Industry ◽  
Initial Glucose Concentration ◽  
Glucose Limitation ◽  
Flocculation Mechanism ◽  
Cyclic Behaviour ◽  
Cultural Conditions ◽  
Yeast Flocculation ◽  
Flocculation Ability

Flocculation onset, the time during the fermentative cycle at which the strains of Saccharomyces cerevisiae become flocculent, is an important factor in the brewing industry. The flocculation ability of Flo1 phenotype (strain NCYC 869) remained practically unchanged throughout the growth and seems to be insensitive to the presence of nutrients of the culture medium. On the contrary, the flocculation of NewFlo phenotype (strain NCYC 1195) exhibited a cyclic behaviour. It was found that the loss of flocculation in the early growth was the result of two combined effects: the dismantling of the flocculation mechanism of the cells coming from the inoculum and the nonflocculent state of the new cells produced after growth has started. The onset of flocculation of strain NCYC 1195 in the cultural conditions used in this work coincided with the end of the exponential growth, when the minimum glucose level in the culture medium was attained. It was demonstrated that it is possible to manipulate the flocculation onset by changing the initial glucose concentration in the culture medium.Key words: yeast, flocculation inhibition, glucose limitation, flocculation onset, genealogical age.

scholarly journals Effect of cultural and nutritional conditions on the control of flocculation expression in Saccharomyces cerevisiae

1994 ◽  
Vol 40 (10) ◽  
pp. 851-857 ◽  
Author(s):  
Eduardo V. Soares ◽  
José A. Teixeira ◽  
Manuel Mota
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nitrogen Source ◽  
Growth Temperature ◽  
Culture Medium ◽  
Phenotypic Expression ◽  
Defined Medium ◽  
Nutritional Conditions ◽  
Flocculation Ability ◽  
Initial Ph ◽  
Defined Culture

The effect of cultural (temperature and pH) and nutritional conditions (nitrogen and carbon source) on the flocculation expression of three strains was studied. The strains' flocculation ability was determined by placing the cells in a stationary phase of growth in standard flocculation conditions. The flocculation ability of strain NCYC 1195, recently classified in the literature as the NewFlo phenotype, was more sensitive to growth temperature than Flo1 phenotype strains (NCYC 869 and NRRL Y265). The initial pH of the culture medium did not affect the flocculation ability of Flo1 phenotype strains but in the case of strain NCYC 1195 flocculation was repressed when the initial pH of the culture medium was below 3.5. Flocculation in strain NCYC 1195 was also repressed in defined culture medium; this inhibition was not related to a deficiency in any particular nitrogen source, but rather to the poor buffering capacity of the defined medium. All strains showed strong flocculation when grown in glucose, but were nonflocculent in glycerol. It was clearly demonstrated that the phenotypic expression of flocculation could be induced or repressed by changing cultural and nutritional conditions. Two distinct behaviours were also displayed with regard to the effect of the cultural conditions upon flocculation, namely the effect of pH. These different behaviours can be used to distinguish the two flocculation phenotypes.Key words: Saccharomyces cerevisiae, flocculation, growth temperature, pH, nitrogen source.

A biometric study of higher alcohol production in Saccharomyces cerevisiae

1990 ◽  
Vol 36 (1) ◽  
pp. 61-64 ◽  
Author(s):  
Paolo Giudici ◽  
Patrizia Romano ◽  
Carlo Zambonelli
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Key Words ◽  
Isoamyl Alcohol ◽  
Higher Alcohols ◽  
Methionine Biosynthesis ◽  
Higher Alcohol ◽  
Strain Characteristic ◽  
Alcohol Production ◽  
Flocculation Ability ◽  
Individual Strain

A hundred strains of Saccharomyces cerevisiae were examined for the ability to produce higher alcohols. In the strains tested the production of higher alcohols was found to be an individual strain characteristic and, as such, was statistically significant. The characteristics of the strains used (flocculation ability, foaming ability, killer character, and non-H2S production) were found to be uncorrelated to isobutanol and isoamyl alcohol production, whereas the production of high levels of n-propanol was found to be related to inability to produce H2S. This, in turn, suggests a link to methionine biosynthesis. Key words: Saccharomyces cerevisiae, higher alcohols, biometry, H2S production.

Role of cations in the flocculation of Saccharomyces cerevisiae and discrimination of the corresponding proteins

1991 ◽  
Vol 37 (5) ◽  
pp. 397-403 ◽  
Author(s):  
Hiroshi Kuriyama ◽  
Itaru Umeda ◽  
Harumi Kobayashi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Surface ◽  
Inhibitory Effect ◽  
Surface Proteins ◽  
Promoting Effect ◽  
Yeast Strains ◽  
Yeast Flocculation ◽  
Different Types ◽  
Anionic Groups

Asexual yeast flocculation was studied using strong flocculents of Saccharomyces cerevisiae. The inhibitory effect of cations on flocculation is considered to be caused by competition between those cations and Ca2+ at the binding site of the Ca2+-requiring protein that is involved in flocculation. Inhibition of flocculation by various cations occurred in the following order: La3+, Sr2+, Ba2+, Mn2+, Al3+, and Na+. Cations such as Mg2+, Co2+, and K+ promoted flocculation. This promoting effect may be based on the reduction of electrostatic repulsive force between cells caused by binding of these cations anionic groups present on the cell surface. In flocculation induced by these cations, trace amounts of Ca2+ excreted on the cell surface may activate the corresponding protein. The ratio of Sr2+/Ca2+ below which cells flocculated varied among strains: for strains having the FLO5 gene, it was 400 to 500; for strains having the FLO1 gene, about 150; and for two alcohol yeast strains, 40 to 50. This suggests that there are several different types of cell surface proteins involved in flocculation in different yeast strains. Key words: yeast, flocculation, protein, cation, calcium.

Mutational analysis of the Saccharomyces cerevisiae SNF1 protein kinase and evidence for functional interaction with the SNF4 protein

1989 ◽  
Vol 9 (11) ◽  
pp. 5034-5044
Author(s):  
J L Celenza ◽  
M Carlson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Mutational Analysis ◽  
Gene Dosage ◽  
Regulatory System ◽  
Kinase Domain ◽  
Regulatory Function ◽  
Protein Kinase Activity ◽  
Glucose Limitation

The SNF1 gene of Saccharomyces cerevisiae encodes a protein-serine/threonine kinase that is required for derepression of gene expression in response to glucose limitation. We present evidence that the protein kinase activity is essential for SNF1 function: substitution of Arg for Lys in the putative ATP-binding site results in a mutant phenotype. A polyhistidine tract near the N terminus was found to be dispensable. Deletion of the large region C terminal to the kinase domain only partially impaired SNF1 function, causing expression of invertase to be somewhat reduced but still glucose repressible. The function of the SNF4 gene, another component of the regulatory system, was required for maximal in vitro activity of the SNF1 protein kinase. Increased SNF1 gene dosage partially alleviated the requirement for SNF4. C-terminal deletions of SNF1 also reduced dependence on SNF4. Our findings suggest that SNF4 acts as a positive effector of the kinase but does not serve a regulatory function in signaling glucose availability.

scholarly journals Novel static magnetic field effects on green chemistry biosynthesis of silver nanoparticles in Saccharomyces cerevisiae

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ameni Kthiri ◽  
Selma Hamimed ◽  
Abdelhak Othmani ◽  
Ahmed Landoulsi ◽  
Siobhan O’Sullivan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Saccharomyces Cerevisiae ◽  
Silver Nanoparticles ◽  
Magnetic Fields ◽  
Green Chemistry ◽  
Static Magnetic Field ◽  
Culture Medium ◽  
Average Diameter ◽  
Magnetic Field Effects ◽  
Static Magnetic Fields

AbstractThe bacteriocidal properties of silver nanoparticles (AgNPs) depend on their average diameter (toxicity increases with decreasing diameter). In the present work, we describe novel green chemistry biosynthesis of AgNPs from AgNO3 added to cell-free culture medium of baker’s yeast, Saccharomyces cerevisiae, yielding nanoparticles in the range 11–25 nm. However, when yeast was grown in a moderate static magnetic field, AgNPs obtained from the resulting cell-free culture medium, were significantly smaller (2–12 nm) than those obtained without magnetic field. These latter nanoparticles were highly crystalline, stable and near-uniform shape. Furthermore, the antibacterial activity of AgNPs obtained from static magnetic fields were greater than those from control cultures. Static magnetic fields show a promising ability to generate biocidal nanoparticles via this novel green chemistry approach.

scholarly journals Yeast Flocculation Mediated by Overexpression of the Chitin Synthase 2 Gene in Saccharomyces cerevisiae.

1991 ◽  
Vol 55 (11) ◽  
pp. 2901-2903 ◽  
Author(s):  
Masayuki SUDOH ◽  
Hisao SHIMADA ◽  
Mikio ARISAWA ◽  
Keiji YANO ◽  
Masamichi TAKAGI
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chitin Synthase ◽  
Yeast Flocculation

Exogenous dTMP utilization by a novel tup mutant of Saccharomyces cerevisiae

1982 ◽  
Vol 152 (1) ◽  
pp. 111-119
Author(s):  
L F Bisson ◽  
J Thorner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Culture Medium ◽  
De Novo ◽  
The Other ◽  
Normal Cells ◽  
Pyrimidine Bases

The rate and extent of entry of dTMP were measured in strains of Saccharomyces cerevisiae carrying two new tup mutations (tup5 and tup7) and most of the other tup mutations which have been reported previously by others. The tup7 mutation allowed dramatically greater accumulation of dTMP than any of the other mutations tested. Specific labeling of DNA by [CH3-3H]dTMP, fate of the dTMP pool inside of the cells, and degradation of the dTMP in the culture medium were investigated in strains carrying the tup7 mutation. The extracellular dTMP was not appreciably degraded, and that accumulated intracellularly was readily phosphorylated to dTDP and dTTP. Under optimum labeling conditions, 60 to 80% of the total thymidylate residues in newly synthesized DNA were derived from the exogenously provided dTMP, even in the absence of a block in de novo dTMP biosynthesis. An apparent Km for entry of 2 mM dTMP was found. The tup7 mutation increased permeability to dTMP (and some other 5'-mononucleotides), but did not affect uptake of nucleosides and purine and pyrimidine bases. Uptake of dTMP could be almost completely inhibited by moderate concentrations of Pi. These findings and other observations suggest that entry of dTMP in strains carrying the tup7 mutation is mediated by a permease whose function in normal cells is the transport of Pi.

Induction and characterization of morphologic mutants in a natural Saccharomyces cerevisiae strain

2007 ◽  
Vol 53 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Claudia Barberio ◽  
Lucia Bianchi ◽  
Francesca Pinzauti ◽  
Tiziana Lodi ◽  
Iliana Ferrero ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Shape ◽  
Point Of View ◽  
Rich Medium ◽  
Uv Mutagenesis ◽  
Pseudohyphal Growth ◽  
Flocculation Ability ◽  
Mitochondrial Dna Replication ◽  
Ecological Behaviour

Saccharomyces cerevisiae is a good model with which to study the effects of morphologic differentiation on the ecological behaviour of fungi. In this work, 33 morphologic mutants of a natural strain of S. cerevisiae, obtained with UV mutagenesis, were selected for their streak shape and cell shape on rich medium. Two of them, showing both high sporulation proficiency and constitutive pseudohyphal growth, were analysed from a genetic and physiologic point of view. Each mutant carries a recessive monogenic mutation, and the two mutations reside in unlinked genes. Flocculation ability and responsiveness to different stimuli distinguished the two mutants. Growth at 37 °C affected the cell but not the colony morphology, suggesting that these two phenotypes are regulated differently. The effect of ethidium bromide, which affects mitochondrial DNA replication, suggested a possible “retrograde action” of mitochondria in pseudohyphal growth.

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