Historic penicillin mold sample sells at auction for $15,000

March 2 (UPI) -- A sample of a penicillin-producing mold culture grown by Sir Alexander Fleming has sold for nearly $15,000 in an auction held at Bonhams in London. The winning bid was nearly three times the estimated sale price.

In 1928, Fleming discovered the world's first antibiotic after happening upon a bacterial dish contaminated with mold. Fleming, a Scottish biologist, noticed the mold had formed a bacteria-free circle around the bacteria sample.

Fleming continued to grow and test the mold, confirming its antimicrobial properties and naming the active substance penicillin. He determined the antibiotic was safe to use on animals and humans.

In 1945, Fleming received the Nobel Prize for his work with penicillin.

The newly sold mold comes from the estate of Mary Elizabeth Johnston, Fleming's niece. The sample was a gift from Fleming. Johnson kept the mold along with several of her uncle's papers and memorabilia. Fleming frequently gave out samples of his mold cultures as gifts to friends and family.

Another penicillin mold sample -- this one given to Flemings' neighbors as a thank you -- sold for more than $46,000 in December.

"The high prices paid for these lots reflect their importance and the enduring fascination with Sir Alexander Fleming's crucial discovery to which so many millions of people all over the world owe their lives," said Matthew Haley, head of the book department at Bonhams.