Born in Adelaide, Australia, Florey became a leading researcher of the disease process. With colleague Ernst Chain, he isolated penicillin, making possible its wide production and use in treating bacterial diseases.

The son of a boot maker, Florey showed no interest in learning the family business. Instead, his natural curiosity and scholastic ability led him to pursue medical research. Florey attended the University of Adelaide, and after earning his medical degree in 1921, he received a Rhodes Scholarship to study at Oxford University. He also studied at Cambridge University and in the United States as a Rockefeller Foundation traveling fellow before returning to Oxford to earn his Ph.D. in pathology and biochemistry.

Florey had been interested in antibacterial agents for years, and in 1930 he began studying a natural antibacterial substance called lysozyme which had been discovered by Alexander Fleming almost a decade earlier. Florey was the first to...