... Titre du document / Document title. Taxogenetics of the Saccharomyces sensu stricto yeasts fr... more ... Titre du document / Document title. Taxogenetics of the Saccharomyces sensu stricto yeasts from western and South Africa. Auteur(s) / Author(s). NAUMOV GI (1) ; NAUMOVA ES (1) ; SANCHO ED ; KORHOLA M. ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Sci. res ...
In order to study the molecular evolution of the yeasts grouped in the Saccharomyces sensu strict... more In order to study the molecular evolution of the yeasts grouped in the Saccharomyces sensu stricto species complex by analysis of the MEL gene family, we have cloned and sequenced two new species-specific MEL genes from Saccharomyces yeasts: S. paradoxus (MELp) and a Japanese Saccharomyces sp. (MELj). The clones were identified by sequence homology to the S. cerevisiae MEL1 gene. Both clones revealed an ORF of 1413 bp coding for a protein of 471 amino acids. The deduced molecular weights of the α-galactosidase enzymes were 52 767 for MELp and 52 378 for MELj. The nucleotide sequences of the MELp (EMBL accession no. X95505) and the MELj (EMBL accession no. X95506) genes showed 74.7% identity. The degree of identity of MELp to the MEL1 gene was 76.8% and to the S. pastorianus MELx gene, 75.7%. The MELj coding sequence was 75.1% identical to the MEL1 gene and 80.7% to the MELx gene. The data suggest that MEL1, MELj, MELp, and MELx genes are species-specific MEL genes. The strains studied each have only one MEL locus. The MELp gene is located on the S. paradoxus equivalent of S. cerevisiae chromosome X; the MELj gene was on the chromosome that comigrates with the S. cerevisiae chromosome VII/XV doublet and hybridizes to the S. cerevisiae chromosome XV marker HIS3.
Baker's yeast is able to assimilate carbon, nitrogen, phosphorus and sulphur sources toge... more Baker's yeast is able to assimilate carbon, nitrogen, phosphorus and sulphur sources together with a great number of minerals and trace elements into a palatable, nutritious product. The metabolism of yeast is precisely controlled during the production growth phase and thus it is possible to determine the composition of the product by controlling the raw materials. Because of existing deficiencies in the availability of certain trace elements, mainly selenium, in Finnish diets, we started testing the possibilities for enriching yeast with this essential trace element about five years ago. We have succeeded in developing a special yeast product with a selenium concentration of 500 mg/kg dry matter. Selenium was expected, because of its structural similarity to sulphur, to replace sulphur in the biosynthetic reactions of the yeast cell. We have recently studied the incorporation and distribution of selenium in yeast with radioactive selenium (75Se). Analysis of the protein fraction of selenium yeast has shown that selenium is present in all the major soluble proteins. Selenomethionine was identified as the major selenium-containing compound in the protein fraction as well as in the whole cell.
Molasses is widely used as a substrate for commercial yeast production. The complete hydrolysis o... more Molasses is widely used as a substrate for commercial yeast production. The complete hydrolysis of raffinose, which is present in beet molasses, by Saccharomyces strains requires the secretion of alpha-galactosidase, in addition to the secretion of invertase. Raffinose is not completely utilized by commercially available yeast strains used for baking, which are Mel. In this study we integrated the yeast MEL1 gene, which codes for alpha-galactosidase, into a commercial mel baker's yeast strain. The Mel phenotype of the new strain was stable. The MEL1 gene was expressed when the new Mel baker's yeast was grown in molasses medium under conditions similar to those used for baker's yeast production at commercial factories. The alpha-galactosidase produced by this novel baker's yeast strain hydrolyzed all the melibiose that normally accumulates in the growth medium. As a consequence, additional carbohydrate was available to the yeasts for growth. The new strain also produc...
In order to study the molecular evolution of the yeasts grouped in the Saccharomyces sensu strict... more In order to study the molecular evolution of the yeasts grouped in the Saccharomyces sensu stricto species complex by analysis of the MEL gene family, we have cloned and sequenced two new species-specific MEL genes from Saccharomyces yeasts: S. paradoxus (MELp) and a Japanese Saccharomyces sp. (MELj). The clones were identified by sequence homology to the S. cerevisiae MEL1 gene. Both clones revealed an ORF of 1413 bp coding for a protein of 471 amino acids. The deduced molecular weights of the α-galactosidase enzymes were 52 767 for MELp and 52 378 for MELj. The nucleotide sequences of the MELp (EMBL accession no. X95505) and the MELj (EMBL accession no. X95506) genes showed 74.7% identity. The degree of identity of MELp to the MEL1 gene was 76.8% and to the S. pastorianus MELx gene, 75.7%. The MELj coding sequence was 75.1% identical to the MEL1 gene and 80.7% to the MELx gene. The data suggest that MEL1, MELj, MELp, and MELx genes are species-specific MEL genes. The strains studied each have only one MEL locus. The MELp gene is located on the S. paradoxus equivalent of S. cerevisiae chromosome X; the MELj gene was on the chromosome that comigrates with the S. cerevisiae chromosome VII/XV doublet and hybridizes to the S. cerevisiae chromosome XV marker HIS3.
... Titre du document / Document title. Taxogenetics of the Saccharomyces sensu stricto yeasts fr... more ... Titre du document / Document title. Taxogenetics of the Saccharomyces sensu stricto yeasts from western and South Africa. Auteur(s) / Author(s). NAUMOV GI (1) ; NAUMOVA ES (1) ; SANCHO ED ; KORHOLA M. ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Sci. res ...
In order to study the molecular evolution of the yeasts grouped in the Saccharomyces sensu strict... more In order to study the molecular evolution of the yeasts grouped in the Saccharomyces sensu stricto species complex by analysis of the MEL gene family, we have cloned and sequenced two new species-specific MEL genes from Saccharomyces yeasts: S. paradoxus (MELp) and a Japanese Saccharomyces sp. (MELj). The clones were identified by sequence homology to the S. cerevisiae MEL1 gene. Both clones revealed an ORF of 1413 bp coding for a protein of 471 amino acids. The deduced molecular weights of the α-galactosidase enzymes were 52 767 for MELp and 52 378 for MELj. The nucleotide sequences of the MELp (EMBL accession no. X95505) and the MELj (EMBL accession no. X95506) genes showed 74.7% identity. The degree of identity of MELp to the MEL1 gene was 76.8% and to the S. pastorianus MELx gene, 75.7%. The MELj coding sequence was 75.1% identical to the MEL1 gene and 80.7% to the MELx gene. The data suggest that MEL1, MELj, MELp, and MELx genes are species-specific MEL genes. The strains studied each have only one MEL locus. The MELp gene is located on the S. paradoxus equivalent of S. cerevisiae chromosome X; the MELj gene was on the chromosome that comigrates with the S. cerevisiae chromosome VII/XV doublet and hybridizes to the S. cerevisiae chromosome XV marker HIS3.
Baker's yeast is able to assimilate carbon, nitrogen, phosphorus and sulphur sources toge... more Baker's yeast is able to assimilate carbon, nitrogen, phosphorus and sulphur sources together with a great number of minerals and trace elements into a palatable, nutritious product. The metabolism of yeast is precisely controlled during the production growth phase and thus it is possible to determine the composition of the product by controlling the raw materials. Because of existing deficiencies in the availability of certain trace elements, mainly selenium, in Finnish diets, we started testing the possibilities for enriching yeast with this essential trace element about five years ago. We have succeeded in developing a special yeast product with a selenium concentration of 500 mg/kg dry matter. Selenium was expected, because of its structural similarity to sulphur, to replace sulphur in the biosynthetic reactions of the yeast cell. We have recently studied the incorporation and distribution of selenium in yeast with radioactive selenium (75Se). Analysis of the protein fraction of selenium yeast has shown that selenium is present in all the major soluble proteins. Selenomethionine was identified as the major selenium-containing compound in the protein fraction as well as in the whole cell.
Molasses is widely used as a substrate for commercial yeast production. The complete hydrolysis o... more Molasses is widely used as a substrate for commercial yeast production. The complete hydrolysis of raffinose, which is present in beet molasses, by Saccharomyces strains requires the secretion of alpha-galactosidase, in addition to the secretion of invertase. Raffinose is not completely utilized by commercially available yeast strains used for baking, which are Mel. In this study we integrated the yeast MEL1 gene, which codes for alpha-galactosidase, into a commercial mel baker's yeast strain. The Mel phenotype of the new strain was stable. The MEL1 gene was expressed when the new Mel baker's yeast was grown in molasses medium under conditions similar to those used for baker's yeast production at commercial factories. The alpha-galactosidase produced by this novel baker's yeast strain hydrolyzed all the melibiose that normally accumulates in the growth medium. As a consequence, additional carbohydrate was available to the yeasts for growth. The new strain also produc...
In order to study the molecular evolution of the yeasts grouped in the Saccharomyces sensu strict... more In order to study the molecular evolution of the yeasts grouped in the Saccharomyces sensu stricto species complex by analysis of the MEL gene family, we have cloned and sequenced two new species-specific MEL genes from Saccharomyces yeasts: S. paradoxus (MELp) and a Japanese Saccharomyces sp. (MELj). The clones were identified by sequence homology to the S. cerevisiae MEL1 gene. Both clones revealed an ORF of 1413 bp coding for a protein of 471 amino acids. The deduced molecular weights of the α-galactosidase enzymes were 52 767 for MELp and 52 378 for MELj. The nucleotide sequences of the MELp (EMBL accession no. X95505) and the MELj (EMBL accession no. X95506) genes showed 74.7% identity. The degree of identity of MELp to the MEL1 gene was 76.8% and to the S. pastorianus MELx gene, 75.7%. The MELj coding sequence was 75.1% identical to the MEL1 gene and 80.7% to the MELx gene. The data suggest that MEL1, MELj, MELp, and MELx genes are species-specific MEL genes. The strains studied each have only one MEL locus. The MELp gene is located on the S. paradoxus equivalent of S. cerevisiae chromosome X; the MELj gene was on the chromosome that comigrates with the S. cerevisiae chromosome VII/XV doublet and hybridizes to the S. cerevisiae chromosome XV marker HIS3.
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