Who was Alexander Fleming what did he did?

Alexander Fleming was a Scottish bacteriologist best known for his discovery of penicillin in 1928, which marked the beginning of modern antibiotics. While conducting experiments at St. Mary's Hospital in London, he noticed that a mold called Penicillium notatum had contaminated one of his bacterial cultures and was killing the surrounding bacteria. This accidental observation led to the development of penicillin as a therapeutic agent, revolutionizing medicine and saving countless lives. Fleming's work earned him the Nobel Prize in Physiology or Medicine in 1945, which he shared with Howard Florey and Ernst Boris Chain for their contributions to the development of penicillin as a drug.