By: HISTORY.com Editors

1928

Penicillin discovered by Sir Alexander Fleming

Published: February 09, 2010

Last Updated: May 27, 2025

Sir Alexander Fleming was a young bacteriologist when an accidental discovery led to one of the great developments of modern medicine on September 3, 1928. Having left a plate of staphylococcus bacteria uncovered, Fleming noticed that a mold that had fallen on the culture had killed many of the bacteria. He identified the mold as penicillium notatum, similar to the kind found on bread.

In 1929, Fleming introduced his mold by-product called penicillin to cure bacterial infections.

Timeline

Also on This Day in History

Discover more of the major events, famous births, notable deaths and everything else history-making that happened on September 3rd

Related Articles

The image shows a wooden wheelchair with a cushioned seat and backrest, featuring a sturdy frame and large wheels.

The first known representation of a wheelchair dates all the way back to the year 525.

black and white photo of a white biplane on a sandy beach with a man lying in the center and another standing in black to the right of the aircraft.

The historic moment was captured by a photography novice.

Underwater seamount.

Amid the search for enemy submarines, Navy researchers detected something much bigger—underwater volcanic mountains rising from the seafloor.

The origin story of the first iPhone reveals that Jobs was just trying to make a really cool phone.

About the author

HISTORY.com Editors

HISTORY.com works with a wide range of writers and editors to create accurate and informative content. All articles are regularly reviewed and updated by the HISTORY.com team. Articles with the “HISTORY.com Editors” byline have been written or edited by the HISTORY.com editors, including Amanda Onion, Missy Sullivan, Matt Mullen, Christian Zapata and Cristiana Lombardo.

Fact Check

We strive for accuracy and fairness. But if you see something that doesn't look right, click here to contact us! HISTORY reviews and updates its content regularly to ensure it is complete and accurate.

Citation Information

Article title
Penicillin discovered by Sir Alexander Fleming
Website Name
History
Date Accessed
June 06, 2025
Publisher
A&E Television Networks
Last Updated
May 27, 2025
Original Published Date
February 09, 2010

History Every Day

Sign Up for "This Day in History"

Uncover fascinating moments from the past every day! Learn something new with key events in history, from the American Revolution to pop culture, crime and more.

By submitting your information, you agree to receive emails from HISTORY and A+E Global Media. You can opt out at any time. You must be 16 years or older and a resident of the United States.