Being new to the group and a relative novice I'm a bit hesitant to
chime in, but I do have A LOT of experience with yeast having
maintained many yeast cultures (home brewing) for several years now.

Among homebrewers, there are several prevalent myths:

First is that yeast can only be "re-used" for 4 or 5 generations and
then only if you are going to reuse them in a short time. The concern
is mutation of the yeast which will ultimately alter your beer. I
have several cultures that I've maintained for over 4 years and none
of them have exhibited any change in characteristics.

Second is that if one is going to attempt a Lambic the entire house
must be sterilized afterwards as the "wild yeast" will take over and
all of your follow-on brews will take on the unique characteristics of
a lambic. Again, I've maintained and brewed with "wild" lambic yeasts
(and are they really wild if you order them from a laboratory?)
without any migration into subsequent fermentations.

The only conclusions I can draw is that yeast strains are as unique
and individual as the rest of us and while susceptible to mutations
and migrations, these things take time and proper care will if not
prevent, at least forestall significant changes. Some strains prefer
different conditions (lager vs ale yeasts) to perform at their peak
and all produce different results (flavors) depending on their
environment and diet.

Again, I'm new to sourdough, but if brewing yeasts are that varied, I
can't imagine that baking yeasts would be all that different. The
questions that beg a

Has anyone done any research on wild yeast strains by region? i.e.
Are there unique qualities associated with starters grown with 'local
wild yeasts?"

and:

How many different starters (strains) do people maintain at any given
time?

and lastly:

Anyone ever try brewers yeast? It thrives in an acid environment but I
think you'd have to inoculate the batch with the bacteria to complete
the process.

Just a couple of random thoughts...


All the best,
Bill P.