From an effect to an object of study
Fleming observed bacterial inhibition near a mould in 1928 and published his work in 1929. Material initially called penicillin was a culture filtrate containing active substance, not a standardized purified medicine. Susceptibility, preservation and possible therapeutic use still needed investigation after the initial observation.
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Extraction, assays and treatment experiments
Florey, Chain, Heatley and Oxford colleagues studied extraction, concentration and potency and conducted animal and clinical work. Instability and scarcity complicated investigation. Reliable assays and adequate supplies were necessary to compare results. Moving from a culture dish to a ward required coordinated biological, chemical and practical work.
References: [1]
Why scaling fermentation mattered
During the Second World War, British and American institutions and companies improved strains, media and production equipment. Deep-tank fermentation increased output, requiring aeration, mixing, contamination control and recovery. A useful laboratory substance was not automatically a dependable industrial product; manufacturing changes transformed limited samples into distributable supplies.
Discovery, development and supply
The 1945 Nobel Prize recognized Fleming, Chain and Florey for discovery and therapeutic effects. Its three recipients do not represent every contributor to assays, recovery, fermentation and manufacture. Nor is penicillin effective against every pathogen. Its history belongs within the broader study of antibacterial action, susceptibility and resistance.