How Parke-Davis could have made a fortune in 1929 from the ultimate in generic drugs : natural penicillin

Parke-Davis, as seen from my folks' homes

A medication made by some natural being out in Nature is the 'ultimate generic drug'  ---- being PD (Public Domain) from its birth, which possibly occurred hundreds of millions of years before Humanity first noticed it.

Penicillin - in theory - is one such 'ultimate generic drug' , but was it in fact, in 1929 ?