penicillin G biosynthesis PMID:15719552 KEGG:map00311 UPa:UPA00149 Biosynthesis of penicillin G, a beta-lactam antibiotic. Penicillin G is one of the mainly used antibiotics for the therapy of infectious diseases. It is produced as end product by some filamentous fungi only, most notably by Aspergillus (Emericella) nidulans and Penicillium chrysogenum. The penicillin biosynthesis is catalysed by three enzymes which are encoded by the following three genes: pcbAB (acvA), pcbC (ipnA) and penDE (aatA). pathway KEGG:map01100 KEGG:map01110 antibiotic biosynthesis penicillin biosynthesis