Learned the new items for the day, re the yeast and the chromosome numbers. Back a while, I knew there were differences in lager yeasts, and then it was termed Carlsberg or Tuborg types.
Saaz-type strains are diploids that contain one set (haploid) of Saccharomyces cerevisiae (S. cerevisiae) chromosomes and one set (haploid) of Saccharomyces eubayanus (S. eubayanus) chromosomes. Frohberg-type strains are triploids that contain two sets (diploid) of S. cerevisiae and one set (haploid) of S. eubayanus genes. Both families inherited their cold tolerance genes from S. eubayanus.
While the first lager strain isolated at Carlsberg Laboratory was a diploid Saaz-type yeast strain (Carlsberg No. 1, which is available in its original form from CBS-KNAW in the Netherlands and the NCYC in the UK, http://www.ncyc.co.uk/yeast-ncyc-396.html
), not all Carlsberg yeast strains are diploids. I know for a fact that Carlsberg production strain No. 244 is a tetraploid (4 sets of chromosomes) with aneuploidy (with respect to brewer's yeast, aneuploidy is a condition where the total number of chromosomes is not a multiple of 16). This information has been confirmed by Jürgen Wendland at Carlsberg Laboratory.
Speaking of Jürgen Wendland, here is a link to a paper that he and his colleagues just published about lager yeast genetics: http://www.g3journal.org/cgi/pmidlookup?view=long&pmid=24578374
. If the information presented in this paper withstands the rigors of peer review, he and his team are about to re-write what we know about the Saaz and Frohberg families. He proposes that the Saaz strains are triploids with one set (haploid) S. cerevisiae chromosomes and two sets (diploid) of S. eubayanus chromosomes. He also proposes that the Frohberg strains are tetraploids with two sets (diploid) S. cerevisiae chromosomes and two sets (diploid) of S. eubayanus chromosomes.
I have only exchanged a couple of e-mails messages with Jürgen, but he is definitely a guy with whom I would like spend some time talking about yeast genetics. He is a rockstar in the world of yeast genetics.
I would think that some of the Midwestern breweries would have strains brought from Germany, as many of those were established at or around the big immigration wave in the 1870s. Any thoughts on German strains used?
Well, it appears that the Christian Schmidt strain was also popular in the Midwest. However, we need to put things into context. Christian Schmidt took over a former ale brewery in 1860 (the Courtenay Brewery). At that point in time, all yeast cultures were mixed cultures, as the first pure lager yeast culture was not isolated until 1883. It's unclear when the first pure Christian Schmidt culture was isolated.