The international auction house Bonham’s has sold a small, patchy disc of mould for $14,597 (£11,863).
The off-white, nearly 90-year-old swatch of mould was first created by Alexander Fleming to make penicillin, a revolutionary discovery that brought the world its first antibiotic.
Bonham’s sold the mould on Wednesday at auction in London. It is preserved in a glass case and features an inscription by Fleming on the back, identifying it as “the mould that first made penicillin”.
That, however, may be stretching the truth; Fleming probably made dozens of the mould mementos.
Matthew Haley, director of books and manuscripts at Bonham’s, said Fleming often sent the samples out to dignitaries including the Pope and Marlene Dietrich as “a kind of holy relic”.
In 1928 Fleming was working on cultures of Staphylococcus, a bacterium which causes blood poisoning. A mould spore accidentally fell on one of these cultures and began to grow. Fleming noticed that the bacteria around the expanding culture began to disappear. Instead of throwing the dirty Petri dish away, he decided to look at what it was that was killing the bacteria, and it turned out to be Penicillium chrysogenum.
He found that the broth in which he had cultivated it was very active against certain types of bacteria, and that it owed this property to a substance secreted by the mould. He suggested that it might be used as an antiseptic in wounds, and published an account of this work in 1929.
However, he couldn’t find a way of extracting enough of the penicillin to be of therapeutic use without it becoming ineffective. It took two Oxford University scientists, Howard Florey and Ernst Chain, to realise its full potential almost a decade later. The three men shared the Nobel prize for medicine in 1945.