Effect of cultural and nutritional conditions on the control of flocculation expression in <i>Saccharomyces cerevisiae</i>

Soares, Eduardo V.; Teixeira, J. A.; Mota, M.

doi:10.1139/m94-135

Cited by 42 publications

(38 citation statements)

References 38 publications

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“…Flocculation of yeast cells belonging to Flo1 phenotype is specifically inhibited by mannose and derivatives; on the other hand, NewFlo phenotype contains the majority of brewery ale strains, which flocculation is reversibly inhibited by mannose, maltose, glucose and sucrose but not by galactose (Stratford and Assinder 1991). Flo1 and NewFlo strains also display different sensitiveness to culture conditions, such as temperature (Soares et al 1994), pH (Soares et al 1994;Stratford 1996;Soares and Seynaeve 2000) and nutrients availability (Soares and Mota 1996).…”

Section: Introductionmentioning

confidence: 99%

Flocculation in ale brewing strains of Saccharomyces cerevisiae: re-evaluation of the role of cell surface charge and hydrophobicity

Holle

Machado

Soares

2011

Appl Microbiol Biotechnol

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Flocculation is an eco-friendly process of cell separation, which has been traditionally exploited by the brewing industry. Cell surface charge (CSC), cell surface hydrophobicity (CSH) and the presence of active flocculins, during the growth of two (NCYC 1195 and NCYC 1214) ale brewing flocculent strains, belonging to the NewFlo phenotype, were examined. Ale strains, in exponential phase of growth, were not flocculent and did not present active flocculent lectins on the cell surface; in contrast, the same strains, in stationary phase of growth, were highly flocculent (>98%) and presented a hydrophobicity of approximately three to seven times higher than in exponential phase. No relationship between growth phase, flocculation and CSC was observed. For comparative purposes, a constitutively flocculent strain (S646-1B) and its isogenic non-flocculent strain (S646-8D) were also used. The treatment of ale brewing and S646-1B strains with pronase E originated a loss of flocculation and a strong reduction of CSH; S646-1B pronase E-treated cells displayed a similar CSH as the non-treated S646-8D cells. The treatment of the S646-8D strain with protease did not reduce CSH. In conclusion, the increase of CSH observed at the onset of flocculation of ale strains is a consequence of the presence of flocculins on the yeast cell surface and not the cause of yeast flocculation. CSH and CSC play a minor role in the auto-aggregation of the ale strains since the degree of flocculation is defined, primarily, by the presence of active flocculins on the yeast cell wall.

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Section: Introductionmentioning

confidence: 99%

Flocculation in ale brewing strains of Saccharomyces cerevisiae: re-evaluation of the role of cell surface charge and hydrophobicity

Holle

Machado

Soares

2011

Appl Microbiol Biotechnol

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“…[8][9][10][11] Environmental factors such as pH, calcium, and organic stress also affect flocculation. 9,[12][13][14] The five FLO genes, FLO1, FLO5, FLO9, FLO10, and FLO11, have been described in S. cerevisiae thus far. [15][16][17][18][19] The FLO1, 5, 9, and 10 genes confer cell-cell adhesion (flocculation) ability, whereas FLO11 is responsible for substrate adhesion.…”

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confidence: 99%

Construction of FlocculentKluyveromyces marxianusStrains Suitable for High-Temperature Ethanol Fermentation

Nonklang

Ano²,

Abdel-Banat

et al. 2009

Bioscience, Biotechnology, and Biochemistry

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Flocculating yeasts are highly useful in fermentation processes because these cells can be separated easily from the fermentation mash. However, native yeasts are usually non-flocculating, including Kluyveromyces marxianus, which exhibits a potent high-temperature ethanol fermentation ability. We describe here the construction of flocculent K. marxianus strains via the introduction of the FLO1, FLO5, FLO9, and FLO10 genes from Saccharomyces cerevisiae. The S. cerevisiae FLO genes were overexpressed by upstream insertion of the constitutive TDH3 promoter, resulting in flocculent S. cerevisiae strains. These TDH3p-FLO sequences were then amplified by PCR and introduced directly into a K. marxianus strain. These K. marxianus strains showed a flocculation phenotype, indicating that the introduced S. cerevisiae TDH3 promoter and all FLO genes were functional in this strain. Moreover, a flocculating K. marxianus strain showed the same ethanol production profile as that of its wild-type parent. The K. marxianus flocculating strains we generated should be useful in the future development of cost-effective fed-batch and continuous fermentation systems at high temperatures.Key words: Kluyveromyces marxianus; yeast; flocculation; ethanol fermentationFlocculation is an attractive property in industrial yeasts because the cells can be easily separated from a fermentation mash. The application of flocculating strains to industrial fermentation processes removes the need for extensive and costly cell separation equipment, and these yeasts are thus suitable for both fedbatch and continuous fermentation. [1][2][3][4] In addition, flocculating yeast cells are useful in immobilized cell systems with no inert support materials. 5) However, although flocculation mechanisms and the introduction of this property to non-flocculent yeast strains have been extensively studied in S. cerevisiae, few studies of this nature have been undertaken in other yeast species. 6,7) The mechanism of yeast flocculation involves the interaction of lectin-like proteins, called flocculins, with receptors on a neighboring cell wall, resulting in the formation of aggregates. [8][9][10][11] Environmental factors such as pH, calcium, and organic stress also affect flocculation. 9,[12][13][14] The five FLO genes, FLO1, FLO5, FLO9, FLO10, and FLO11, have been described in S. cerevisiae thus far. [15][16][17][18][19] The FLO1, 5, 9, and 10 genes confer cell-cell adhesion (flocculation) ability, whereas FLO11 is responsible for substrate adhesion. 20) FLO1, FLO5, and FLO9 are highly similar to each other, but FLO10 has lower similarity. The mechanisms of flocculation in other yeasts appear to be lectin-based but of differing specificities. For instance, galactose and its derivatives have been found to inhibit flocculation of K. bulgaricus and K. lactis, suggesting that this interaction involves a galactose-specific lectin. 21,22) The advantages of using flocculating yeast cells in fermentation processes have led to many studies on the construction of flocculent s...

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“…The result showed that the flocculation ability of the transformant ZWA46-F2 is stable during serial batch cultivations. Yeast flocculation is optimal in slightly acidic conditions, pH from 3.5 to 5.8 (Jin and Speers 2000;Soares et al 1994). The flocculins may be inactive at certain pH values due to conformational changes that occur when the electrostatic charge of surface proteins changes (Jin and Speers 2000;Soares et al1994).…”

Section: Flocculation Property Of the Transformant Zwa46-f2mentioning

confidence: 99%

“…Flocculation is also affected by cultural and nutritional conditions. However flocculation is a very strain-specific character, making it difficult to predict specific phenomenon (Soares et al 1994;Verstrepen et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Construction of a flocculating yeast for fuel ethanol production

Wang

Shen²,

Rao³

et al. 2007

Biotechnol Lett

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The expression vector pYX212 harboring FLO1 gene and kanMX gene was transformed into Saccharomyces. cerevisiae ZWA46. The transformant, ZWA46-F2, showed strong and stable flocculation ability during 20 serial batch cultivations. The flocculation onset of the strain is in the early stationary growth phase, not coincident with the glucose depletion in the culture medium. The flocculation ability of the transformant showed no difference with the initial pH ranging from 3.5 to 6.0. Furthermore, the ethanol concentration and other properties of the transformant strain ZWA46-F2 were similar to those of the wild-type strain ZWA46.

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

Cited by 42 publications

References 38 publications

Flocculation in ale brewing strains of Saccharomyces cerevisiae: re-evaluation of the role of cell surface charge and hydrophobicity

Flocculation in ale brewing strains of Saccharomyces cerevisiae: re-evaluation of the role of cell surface charge and hydrophobicity

Construction of FlocculentKluyveromyces marxianusStrains Suitable for High-Temperature Ethanol Fermentation

Construction of a flocculating yeast for fuel ethanol production

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