A study of the effect of calcium chloride (CaCl2) and pH on the flocculation ability of Saccharomyces cerevisiae (NCYC 1195)

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.

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

Canadian Journal of Microbiology ◽

10.1139/w06-132 ◽

2007 ◽

Vol 53 (2) ◽

pp. 223-230 ◽

Cited By ~ 2

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

Canadian Journal of Microbiology ◽

10.1139/m96-073 ◽

1996 ◽

Vol 42 (6) ◽

pp. 539-547 ◽

Cited By ~ 39

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.

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

Canadian Journal of Microbiology ◽

10.1139/m94-135 ◽

1994 ◽

Vol 40 (10) ◽

pp. 851-857 ◽

Cited By ~ 38

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.

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