Thats amazing what can be done nowadays.
Yeast is around everywhere its in the air as a bread maker one can capture wild yeast by mixing flour and water leaving it open and the yeast in the air will invade it and one makes a bread starter in this fashion.
San Francisco is world famous for there sour dough bread a certain strain that is in the air their that is used but its not here in Illinois !
Thanks for the link it was read and interesting.