Dick,.... yes there is such 'additive or whatever you call it that when
you add to the dough in small amount you can make a sourdough out if
it. Le Saffre in France( the manufacturer of Saf yeast is one known
supplier of such item. But in order to use it properly you willl have
to add bakers yeast in order that the dough will rise properly.
The same thing also will be expected with similar products made in
Germany.
I am certain that such material will be subject to criticism and
opposition from this group.<g>.
Roy