Alexander Fleming

Bacteriologist

Alexander Fleming is famous for discovering the usefulness of penicillin as an antibacterial agent. Raised in rural Scotland, he moved to London in his teens and worked as a shipping clerk and served in the Territorial Army. He earned his medical degree in 1906 from St. Mary's Medical School, where he spent his career (with the exception of a stint as a medical corps captain during World War I). A researcher in the area of antiseptics and antibacterial substances, in 1921 he discovered a natural protein with bacteria-killing properties that he named lysozome. In his lab in 1928 Fleming discovered some bacteria-repelling mold in an uncovered culture of staphylococci. He identified the mold as Penicillium notatum and published his findings in 1929, naming the substance penicillin. Fleming lacked sufficient chemistry skills to exploit his findings, but years later penicillin was developed by Howard Florey and Ernest Chain into the first significant antibiotic. Fleming was knighted in 1944, and in 1945 he shared the Nobel prize in medicine and physiology with Florey and Chain.