Final answer:
Alexander Fleming discovered penicillin in 1928, with Howard Florey and Ernst Chain later developing its mass production. Together they ushered in a new era of medicine, earning a Nobel Prize for their contribution.
Step-by-step explanation:
The individual accredited with the discovery of penicillin, marking the beginning of the "Age of Medicine," was Alexander Fleming in 1928. Fleming identified antibacterial properties in a mold that had contaminated a petri dish he was using to culture Staphylococcus bacteria. However, the development and mass production of penicillin as an antibiotic were advanced by a team at Oxford University led by Howard Florey and Ernst Chain. It was their dedication that made penicillin widely available, especially during World War II, earning them along with Fleming the Nobel Prize in Physiology and Medicine in 1945.
In a remarkable case of serendipity, penicillin was discovered when Fleming noticed the mold Penicillium notatum had killed the bacteria in his petri dish. It was Florey and Chain who realized the potential of penicillin and developed ways to purify and produce it in bulk, which included cultivating the mold in a corn-based nutrient medium and later using a high-yielding strain from Illinois. Their work was pivotal in saving countless lives and is a foundation of modern medical practice.