In facilities they inoculate the 'dough' with the culture. I am not overly worried anymore about various molds tbh. It is only in the last century that people have begun to create pure strains across the board. I have a feeling this has removed a lot of character from fermented foods. In fact, true fermented foods are becoming more rare. I blame our fear of germs on this. Sure there are a lot of nasty critters running around out there, but we have time honored traditions that have given us methods for safe preservation of food via fermentation. If you embark on this endeavor keep us posted. This is on my 'to do' list and has been for a while. Although the book I have, the Miso supposedly takes over a year to mature.