S.cerevisiae progenitors

Mick mick at blankley.prestel.co.uk
Wed Jul 23 01:01:24 EST 1997


Dennis Walker wrote:

> I am an amateur brewer trying to recreate
> a medieval beer recipe from 16th century England as closely as possible.
> I would like to try to get
> a little closer than ripping open a packet of modern engineered brewers'

Modern brewers yeast may be less engineered than you think. It is often
said that the best traditionally brewed beers have a microbiological zoo
inside them. It may not be true, of course... but in my yeasty
enthusiasm I did a sort-of experiment a few years ago when I went to the
local trendy bottled beer shop (you know, the sort that sells strange
varieties of beer from around the world) and plated out the residue from
quite a few different bottles onto YPD plates. Yes, I was careful to
exclude contamination; and most were sterile.  But of the bottles that
were not sterile, they often contained more than one variety of yeast,
judging by cell morphology and appearance of the colonies.  The wierdest
I got was some stuff from Indonesia, which seemed to hvae been fermented
mainly by something filamentous.

Anyway, the message is that it is likely "selection" rather than
"engineering" that, until very recently and even now in some cases, gave
us our brewing strains. I suspect your medieval recipe does not call for
the addition of yeast, but rather, relies on yeast from some
environmental source (like in the production of wine?)  If so, it should
be quite easy to duplicate (but it might still taste horrible!)

Michael Pocklington



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