Fermenting Soy Milk?

Howdy! I recently read the article-abstract found here(confex.comjfs67Open ↗
3104.htm), and I was wondering how I could ferment soy milk
with b. longum so that the daidzein molecules would be
metabolized to equol(as it says in the article). Would
simply mixing store-bought b. longum probiotics in a store-
bought container of soy milk be enough to metabolize the
daidzein to equol, or would I have to use a more complex
procedure? Does fermentation even have to occur for the
metabolization to occur? Supposedly, the majority of
commercial soy milks are produced from soy isolates which do
not ferment well.... so, assuming i bought or made natural
soy milk from whole soy beans, how would I ferment it with
b. longum? How much b. longum would I need? Could I just add
the powdered form of the probiotic that they sell in health
food stores, or do I need some sort of fermentation-grade(?)
quality of the strain? really confused/please help