Today, most commercial varieties of this antibiotic are produced by the mold P. chrysogenum
Shortly thereafter, Moyer made the even more important discovery 
that the... [DOC] [TLE] Production of Antibiotics [PAR] Production of Penicillin in Industrial Fermenters (Bioreactors) ... of stainless steel, 
containing a liquid medium in which Penicillium chrysogenum is grown.