26
edits
Changes
→S. pastorianus
For a long time the origins of the hybrid were unknown and was postulated to be a hybrid between ''S. cerevisiae'' and ''S.uvarum'', or ''S. cerevisiae'' and ''S.bayanus''. Recent work eg. Libkind et al 2011 proved that the hybridisation was between ''S. eubayanus'', which had been recently found in South America and ''S. cerevisiae''.
Separated into two main lineages, "Saaz" and "Frohberg". The two lineages are believed to have descended from different hybridisation events between ''S. eubayanus'' and ''S. cerevisiae''. The two lineages also have different genetic structure, with Frohberg types having two copies of each of the ''S. eubayanus'' and ''S. cerevisiae'' chromosomes (triploid), and Saaz types having one copy of the ''S. cerevisiae'' chromosomes and two copies of the ''S. eubayanus'' chromosomes (allotetraploid). (Ref: https://www.ncbi.nlm.nih.gov/pubmed/24578374 ) Emil Christian Hansen was the first in the world to isolate a single pure strain of ''S. pastorianus'' while he was working at the Carlsberg brewery, leading to its the synonymous classification name, ''S. carlbergensis''. The type that Hansen isolated was a Saaz type, and it's believed that Saaz types are also prevalent in Bohemian / Czech ''S. pastorianus'' strains while German types are typically Frohberg. ([https://onlinelibrary.wiley.com/doi/full/10.1002/yea.2960] , [https://genome.cshlp.org/content/18/10/1610.full] )
With recent whole genome sequencing data, it has been discovered that some strains of commercial yeast have been misidentified as either lager yeast or ale yeast. [http://sykesey.id.au/?p=20 Ben Sykes reported] that publicly available genetic data for an upcoming study indicates that WLP800, the Czech lager yeast from White Labs, is potentially ''S. cerevisiae'' (ale yeast). WLP029 German Ale/ Kölsch Yeast is potentially lager yeast.