During the second world war, chemists made penicillin by culturing moulds in pans.

Labs would have these pans stacked to the ceiling, but the process still yielded only tiny amounts of penicillin.

The compound was in such short supply that unmetabolised remnants of the drug were being recycled from soldiers’ urine.

Reference

Howgego, J. (2018) Roaming Free. New Scientist. 19 May 2018, pp.39-41.