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A dendogram showing the genetic/evolutionary relationship
between various species of yeasts. From Reference 1. |
So last night I met with the
London Homebrewers president, and we planned out something special. I'm not going to say more here - but lets just say once this new project gets rolling it'll blow my blog (and the activities it covers) out of the water.
But, as part of the meeting, our discussion turned to questions like 'what is
Brett', 'how does a strain of
Brett (or lacto, etc) compare to a yeast strain', etc. In other words, what is the difference between wyeast 1056, 1084 & 2001 (American Ale, Irish Ale and Plisner Urquell respectively), and how does that compare to
Brettanomyces bruxellensis or
lambicus?
Before going into the details, a brief note on how science organizes species. We organize based on genetic/evolutionary similarity - i.e. if we had two strains that were genetically similar, and one less genetically similar, we would cluster the more similar species together. An example of this can be seen in the attached image -
Saccharomyces cerevisiae (top of image) is grouped separate from the
Dekkara/Brettanomyces yeasts, while the the
Dekkara/Brettanomyces are clustered together The numbers on the lines indicate the relative amount of genetic differences between species, so we can say that
Saccharomyces is slightly more similar to
Hansenispora occidentalis (71+75 = 146 units of difference) than it is to
Brett. bruxellensis (100 + 51 + 100 = 251 units). This mapping allows us to group organisms based on similarity, giving us the ability to separate organisms into strains, species, genera, and higher taxonomical orders. But yeast - being the nightmares of taxonomists - don't play nice...
As always, details below the fold.