Who experimented with deep-submergence penicillin production at NRRL?

Kenneth Bryan Raper experimented with deep-submergence penicillin production at the Northern Regional Research Laboratory, or NRRL. He was an American mycologist working at the USDA laboratory in Peoria, Illinois.

Early penicillin production used shallow pans, an approach developed by the Oxford researchers. Raper investigated growing the mould in liquid inside large tanks instead. The first submerged cultures produced disappointing yields, but the method offered a path to industrial-scale manufacture because tanks could hold far more culture than laboratory trays.

Raper and colleagues also searched for higher-yielding mould strains. In 1943, a Penicillium mould from a cantaloupe sold in a Peoria market became the famous “cantaloupe strain,” designated NRRL 1951. It helped make deep-submergence production far more productive when combined with later strain improvement and fermentation techniques.

Andrew Moyer was also crucial to penicillin production at the NRRL, especially through changes to the growth medium. However, the question asks who experimented with deep-submergence production, making Raper the canonical answer.