Alexander Fleming publishes the first paper describing penicillin and its effect on gram-positive microorganisms. This finding is unique since it is a rare example of bacterial lysis and not just microbial antagonism brought on by the mold Penicillium. Fleming kept his cultures 2-3 weeks before discarding them. When he looked at one set he noticed that the bacteria seemed to be dissolving and the mold was contaminating the culture. When penicillin is finally produced in major quantities in the 1940s, its power and availability effectively launch the “Antibiotics Era,” a major revolution in public health and medicine. With Florey and Chain, Fleming is awarded the Nobel Prize in Medicine or Physiology in 1945.
Fleming, A. 1929. On the antibacterial action of cultures of a Penicillium, with a special reference to their use in the isolation of B. influenze. Brit. J. Exp. Path. 10: 226-236. In Microbiology: A Centenary Perspective, edited by Wolfgang K. Joklik, ASM Press. 1999, p.98 [pdf] and also In Milestones in Microbiology: 1556 to 1940, translated and edited by Thomas D. Brock, ASM Press. 1998, p185 [pdf]