Year of Discovery: A.D. 1928
Why Is This One of the 100 Greatest?
Penicillin has saved millions of lives, tens of thousands during the last years of World War II alone. The first antibiotic to successfully fight bac terial infections and disease, penicillin was called a miracle cure for a dozen killer diseases rampant in the early twentieth century.
Penicillin created a whole new arsenal of drugs in doc tors' toolkits to fight disease and infection. It opened the door to entire new families and new generations of antibiotic drugs. Penicillin started the vast industry of antibiotic drugs and ushered in a new era of medicine.
How Was It Discovered?
In 1928, 47-year-old Scottish born Alexander Fleming was named chief biochemist at St. Mary's Hospital in London and given a basement laboratory tucked in next to the boiler room.
As the staff bacteriologist, he grew (or “cultured”) bacteria in small, round, glass plates for hospital study and experiment. Using microscopic amounts of a bacterium (often collected from a sick patient), he grew enough of each to determine why the patient was sick and how best to fight the infection. Small dishes of deadly staphylococci, streptococci, and pneumococci bacteria were lined and labeled across the one lab bench that stretched the length of Fleming's lab.
Molds were the one great hazard to Fleming's lab operation. Fleming's lab alternated between being drafty and stuffy, depending on the weather and how hard the boiler worked next door. His only ventilation was a pair of windows that opened at ground level to the parklike gardens of the hospital. Afternoon breezes blew leaves, dust, and a great variety of
airborne molds through those windows
. It seemed impossible to keep molds from drifting into, and contaminating, most of the bacteria Fleming tried to grow.
On Septem ber 28, 1928, Fleming's heart sank as he realized that a prized dish of pure (and deadly) staphylococci bacteria had been ruined by a strange, green mold. The mold must have floated into the dish sometime early the previous evening and had been multiplying since then. Greenish mold fuzz now covered half the dish.
Fleming grunted and sighed. Then he froze. Where this strange green mold had grown, the staphylococci bac teria had simply disappeared. Even bacteria more than an inch from the mold had turned transparent and sickly.
What kind of mold could destroy one of the most hearty, tenacious, and deadly bacteria on earth? No other substance then known to man could attack staphylococci so successfully.
It took two weeks for Flem ing to isolate and culture enough of the tough green mold to complete an identification: Penicillium notatum. Within a month he had discovered that the mold secreted a substance that killed bacteria. He began to call this substance “penicillin.”
Through culture dish exper iments he discovered that penicillin could easily destroy all the common human, killing bacteria-staphylococci, streptococci, pneumococci, even the toughest of all, the bacilli of diphtheria. The only bacterium penicillin fought but did not destroy was the weak, sensitive bacterium that caused influenza (flu).
Flem ing spent six months testing penicillin on rabbits to establish that the drug was safe for human use before, in late 1929, announcing the discovery of his miracle mold that had drifted in the window.
However, penicillin was difficult and slow to grow. It worked wonders but was available in such small quantities that it did little practical good.
In 1942 Dorothy Hodgkin, a British re searcher, developed a new process, called X-ray crystalography, to decipher the structure of a penicillin molecule. It took her 15 months and thousands of X-ray images of the molecules in a penicillin crystal to identify each of the 35 atoms in a penicillin molecule. Dr. Hodgkin was awarded the 1964 Nobel Prize for her work.
American doctors Howard Florey and Ernst Chain were able to use Hodgkin's map to synthetically produce  penicillin molecules in mass production beginning in 1943. For their effort, Florey and Chain were awarded the 1945 Nobel Price in Medicine jointly with Alexander Fleming, the discoverer of penicillin.
DO you Know:
American researchers in Peoria, Illinois, were able to de-
velop commercial production of penicillin first, because two of penicillin's favorite foods turned out to be a strain of local Illinois corn and rotting cantaloupes, donated by a Peoria market. Those food bases helped researchers increase their production of penicillin from 400 million to over 650 billion units a month

What Is It? The first commercially available antibiotic drug.
Who Discovered It?  Alexander Fleming