The brilliant but somewhat absent-minded biologist Alexander Fleming was researching a strain of staphylococcus bacteria. One day in 1928, he returned from holiday and found a jar containing a bacterial culture that he had forgotten about. Mould was growing in the jar, so he threw it away. Only later did he notice that the bacterial strain did not seem to grow around the mould. Neither he nor the research community paid much attention to this discovery, as the mould was difficult to cultivate and slow-acting.

 

After further research, penicillin was successfully produced commercially in 1945, changing the treatment of bacterial infections forever.