Saccharomyces pastorianus
Encyclopedia
Saccharomyces pastorianus is a yeast
, used industrially for the production of lager
beer. It is a synonym of the yeast species Saccharomyces carlsbergensis, which was originally described in 1883 by Emil Christian Hansen
, who was working for the Danish
brewery Carlsberg.
(or as recently proposed Saccharomyces eubayanus
, more commonly known as Danjansenanus ) and Saccharomyces cerevisiae
, finding a degree of phenotypic
and genomic similarity between the two species is not surprising. The hybrid nature of S. pastorianus also explains the genome size, which is up to 60% larger than that of S. cerevisiae, as it includes large parts of the two genomes. There is growing evidence, however, that S. pastorianus has inherited most of its genetic material from S. bayanus. Indeed the mitochondrial DNA
and ribosomal DNA
of S. pastorianus appear to be derived from S. bayanus rather than S. cerevisiae.
The genomic difference between S. pastorianus and S. cerevisiae is responsible for a number of phenotypic traits which S. pastorianus shares with S. bayanus, but not S. cerevisiae. The ability of S. pastorianus to break down melibiose
is dependent on up to ten MEL genes, which are exclusive to strains metabolising melibose such as S. bayanus. S. pastorianus never grows above 34 °C (93.2 °F), whereas S. cerevisiae will grow at 37 °C (98.6 °F). S. pastorianus exhibits a higher growth rate than S. cerevisiae at 6 to 12°C.
S. pastorianus has been suggested as a hybrid of S. cerevisiae and S. monacensis, as the LEU2, MET2 and ACB1 genes of S. pastorianus had been reported to have a high level of similarity or be identical to the S. monacensis homologues. However, subtelomeric sequence hybridisation has suggested S. monacensis is likely to be a closely related hybrid to S. pastorianus, rather than an ancestor.
Ale strains are genetically more diverse than lager strains, as lager strains are thought to derive from a hybrid gene pool (Casey, 1996). The lager strains in use are thought to derive from only one or two primary strains, Tuborg and Carlsberg (Casey, 1990; Casey, 1996).
. It is a bottom-fermenting yeast, so-called because it does not form the foam on top of the wort
as top-fermenting yeast
does.
Further research was done by Martinus Willem Beijerinck in 1898; it was synonymized with S. bayanus, but revived by Nguyen and Gaillardin in 2005.
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
, used industrially for the production of lager
Lager
Lager is a type of beer made from malted barley that is brewed and stored at low temperatures. There are many types of lager; pale lager is the most widely-consumed and commercially available style of beer in the world; Pilsner, Bock, Dortmunder Export and Märzen are all styles of lager...
beer. It is a synonym of the yeast species Saccharomyces carlsbergensis, which was originally described in 1883 by Emil Christian Hansen
Emil Christian Hansen
Emil Christian Hansen was a Danish mycologist and fermentation physiologist.Born in Ribe, he financed his education by writing novels and he was awarded a gold medal in 1876 for an essay on fungi....
, who was working for the Danish
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
brewery Carlsberg.
Genomics
As S. pastorianus is a hybrid of either Saccharomyces bayanusSaccharomyces bayanus
Saccharomyces bayanus is a yeast of the genus Saccharomyces, and is used in winemaking and cider fermentation. It is closely related to Saccharomyces cerevisiae. Both Saccharomyces bayanus and Saccharomyces pastorianus contain diverse strains, with different genetic and metabolic characteristics,...
(or as recently proposed Saccharomyces eubayanus
Saccharomyces eubayanus
Saccharomyces eubayanus, a type of yeast, is a likely parent of the lager brewing yeast, Saccharomyces pastorianus.Lager is a type of beer created from malted barley and brewed at low temperatures, originally in Bavaria. S...
, more commonly known as Danjansenanus ) and Saccharomyces cerevisiae
Saccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...
, finding a degree of phenotypic
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
and genomic similarity between the two species is not surprising. The hybrid nature of S. pastorianus also explains the genome size, which is up to 60% larger than that of S. cerevisiae, as it includes large parts of the two genomes. There is growing evidence, however, that S. pastorianus has inherited most of its genetic material from S. bayanus. Indeed the mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
and ribosomal DNA
Ribosomal DNA
Ribosomal DNA codes for ribosomal RNA. The ribosome is an intracellular macromolecule that produces proteins or polypeptide chains. The ribosome itself consists of a composite of proteins and RNA. As shown in the figure, rDNA consists of a tandem repeat of a unit segment, an operon, composed of...
of S. pastorianus appear to be derived from S. bayanus rather than S. cerevisiae.
The genomic difference between S. pastorianus and S. cerevisiae is responsible for a number of phenotypic traits which S. pastorianus shares with S. bayanus, but not S. cerevisiae. The ability of S. pastorianus to break down melibiose
Melibiose
Melibiose is a reducing disaccharide formed by an alpha-1,6 linkage between galactose and glucose . It can be formed by invertase mediated hydrolysis of raffinose, which produces melibiose and fructose. Melibiose can be broken down into its component saccharides, glucose and galactose, by the...
is dependent on up to ten MEL genes, which are exclusive to strains metabolising melibose such as S. bayanus. S. pastorianus never grows above 34 °C (93.2 °F), whereas S. cerevisiae will grow at 37 °C (98.6 °F). S. pastorianus exhibits a higher growth rate than S. cerevisiae at 6 to 12°C.
S. pastorianus has been suggested as a hybrid of S. cerevisiae and S. monacensis, as the LEU2, MET2 and ACB1 genes of S. pastorianus had been reported to have a high level of similarity or be identical to the S. monacensis homologues. However, subtelomeric sequence hybridisation has suggested S. monacensis is likely to be a closely related hybrid to S. pastorianus, rather than an ancestor.
Ale strains are genetically more diverse than lager strains, as lager strains are thought to derive from a hybrid gene pool (Casey, 1996). The lager strains in use are thought to derive from only one or two primary strains, Tuborg and Carlsberg (Casey, 1990; Casey, 1996).
Saccharomyces uvarum
The yeast species Saccharomyces uvarum is believed to have originated as a hybrid of S. cerevisiae and S. monacensis, because of its allopolyploid genomeGenome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
. It is a bottom-fermenting yeast, so-called because it does not form the foam on top of the wort
Wort (brewing)
Wort, , is the liquid extracted from the mashing process during the brewing of beer or whisky. Wort contains the sugars that will be fermented by the brewing yeast to produce alcohol.- Production :...
as top-fermenting yeast
Saccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...
does.
Further research was done by Martinus Willem Beijerinck in 1898; it was synonymized with S. bayanus, but revived by Nguyen and Gaillardin in 2005.
See also
- BrewingBrewingBrewing is the production of beer through steeping a starch source in water and then fermenting with yeast. Brewing has taken place since around the 6th millennium BCE, and archeological evidence suggests that this technique was used in ancient Egypt...
- Bottom and top fermenting yeast
- LagerLagerLager is a type of beer made from malted barley that is brewed and stored at low temperatures. There are many types of lager; pale lager is the most widely-consumed and commercially available style of beer in the world; Pilsner, Bock, Dortmunder Export and Märzen are all styles of lager...
- YeastYeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...