The microbiological production of pharmaceuticals

Manufacture of penicillins is accomplished in a combination of biological and chemical steps; shown here are crystallizers, the site of one of the key processes in production. Manufacture begins in fermentation tanks with a capacity of as much as 100,000 liters. In the tanks an industrial strain of the fungal mold Penicillium chrysogenum is grown in a rich liquid medium; a form of penicillin called penicillin G is a natural metabolite of the fungal cells. In this plant, operated by Pfizer, Inc., In Groton, Conn., as many as 15 fermentation tanks are linked on a staggered production schedule to provide a continuous output of the antibiotic. When fermentation, which takes several days, is complete, penicillin G is separated from the spent mold cells and injected into the crystallizers, where butanol is added. The butanol is evaporated, carrying water with it and leaving behind a crystalline slurry of penicillin G of more than 99 percent purity. Subsequent chemical modifications yield other forms of penicillin.