Saccharomyces pastorianus
| Saccharomyces pastorianus | |
|---|---|
| Scientific classification | |
| Kingdom: | Fungi |
| Phylum: | Ascomycota |
| Subphylum: | Saccharomycotina |
| Class: | Saccharomycetes |
| Order: | Saccharomycetales |
| Family: | Saccharomycetaceae |
| Genus: | Saccharomyces |
| Species: | S. pastorianus |
| Binomial name | |
| Saccharomyces pastorianus Nguyen & Gaillardin ex. Beijerinck |
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| Synonyms | |
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Saccharomyces carlsbergensis |
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Saccharomyces pastorianus is a yeast, used industrially for the production of lager beer. It is a synonym of the yeast species Saccharomyces carlsbergensis,[1] which was originally described in 1883 by Emil Christian Hansen, who was working for the Danish brewery Carlsberg.
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[edit] Genomics
As S. pastorianus is a hybrid of either Saccharomyces bayanus (or as recently proposed Saccharomyces eubayanus, more commonly known as Danjansenanus [2]) and Saccharomyces cerevisiae, finding a degree of phenotypic and genomic similarity between the two species is not surprising.[3] 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.[4] There is growing evidence, however, that S. pastorianus has inherited most of its genetic material from S. bayanus.[4] Indeed the mitochondrial DNA[5] and ribosomal DNA[4] 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 °F), whereas S. cerevisiae will grow at 37 °C (99 °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.[6][7][8] However, subtelomeric sequence hybridisation has suggested S. monacensis is likely to be a closely related hybrid to S. pastorianus, rather than an ancestor.[1]
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).
[edit] 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 genome.[citation needed] 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.[9][10]
[edit] See also
[edit] References
- ^ a b Casaregola, S.; et al. (2001), "Analysis of the constitution of the beer yeast genome by PCR, sequencing and subtelomeric sequence hybridization", International Journal of Systematic and Evolutionary Microbiology 51 (4): 1607–1618, http://ijs.sgmjournals.org/cgi/content/abstract/51/4/1607.
- ^ Libkind, D.; Hittinger, C.; Valério, E.; Gonçalves, C.; Dover, J.; Johnston, M; Gonçalves, P.; Sampaio, J., "Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast", PNAS.
- ^ Tamai, Y.; Momma, T.; Yoshimoto, H.; Kaneko, Y. (1998), "Co-existence of two types of chromosome in the bottom fermenting yeast, Saccharomyces pastorianus", Yeast 14 (10): 923–933, doi:10.1002/(SICI)1097-0061(199807)14:10<923::AID-YEA298>3.0.CO;2-I.
- ^ a b c Montrocher, R.; et al. (1998), "Phylogenetic analysis of the Saccharomyces cerevisiae group based on polymorphisms of rDNA spacer sequences", International Journal of Systematic Bacteriology 48 (1): 295–303, doi:10.1099/00207713-48-1-295.
- ^ Piskur, J.; Smole, S.; Groth, C.; Petersen, R. F. & Pedersen, M. B. (1998), "Structure and genetic stability of mitochondrial genomes vary among yeasts of the genus Saccharomyces", International Journal of Systematic Bacteriology 48 (3): 1015–1024, doi:10.1099/00207713-48-3-1015.
- ^ Hansen, J. & Kielland-Brandt, M. C. (1994), "Saccharomyces carlsbergensis contains two functional MET2 alleles similar to homologues from S. cerevisiae and S. monacensis", Gene 140 (1): 33–40, doi:10.1016/0378-1119(94)90727-7, PMID 8125336.
- ^ Casey, G. P.; Pedersen, M. B. (1988), "DNA sequence polymorphisms in the genus Saccharomyces. V. Cloning and characterization of aLEU2 gene from S. carlsbergensis", Carlsberg Research Communications 53 (3): 209–219, doi:10.1007/BF02904408.
- ^ Borsting, C.; et al. (1997), "Saccharomyces carlsbergensis contains two functional genes encoding the acyl-CoA binding protein, one similar to the ACB1 gene from S. cerevisiae and one identical to the ACB1 gene from S. monacensis", Yeast 13 (15): 1409–1421, doi:10.1002/(SICI)1097-0061(199712)13:15<1409::AID-YEA188>3.0.CO;2-A.
- ^ Nguyen, H. V. & Gaillardin, C. (2005), "Evolutionary relationships between the former species Saccharomyces uvarum and the hybrids Saccharomyces bayanus and Saccharomyces pastorianus; reinstatement of Saccharomyces uvarum (Beijerinck) as a distinct species", FEMS Yeast Research 5 (4–5): 471–483, doi:10.1016/j.femsyr.2004.12.004.
- ^ Saccharomyces uvarum at EPA.gov
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