"Kenneth" wrote in message ...

[ ... ]

It appears that the LB are alive and well, but that the
yeasts are dormant, or dead.

Have any of you had similar experiences, and what might have
caused this to happen?

Yes, for fridge- and dried cultures, but never to the exent that
continued culturing at usual temperatures did not bring back the
yeast activity.

It has been reported that the yeast do drop out upon culturing
at high temperature (~100°F.). Years ago, one poster proposed
this as a way to get very sour bread.

Gaenzle's published data reflects the reason for these effects:
http://aem.asm.org/cgi/content/full/64/7/2616/F

(Somebody kindly forward this post to Kenneth, as he has had
me killfiled since the early times.)

My take is that, at ordinary culturing temperatures, the yeast and
the bacilli coordinate with one another as the result of some features
of their symbiosis. In dough, however, my best guess is that the
bacteria take over in the end, devouring the starving yeast for a
last big contribution of sourdough flavors. Well, if the dough is
strong and healthy enough to ferment that far before one starts
mumbling about overproofedness...

--
Dicky