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Portrait of Ernst B. Chain
Photo: Nobel Foundation, http://nobelprize.org/ · Public domain via Wikimedia Commons

Nobel Prize in Physiology or Medicine · 1945

Ernst B. Chain

A refugee chemist who fled Nazi Berlin, he helped purify penicillin and prove it could cure deadly infections.

The Nobel citation: “for the discovery of penicillin and its curative effect in various infectious diseases”
Born
June 19, 1906, Berlin, Germany
Died
August 12, 1979, Mulrany, Ireland
Shared with
Sir Alexander Fleming, Sir Howard Florey
Affiliation at the time
University of Oxford, United Kingdom

Medicine prize

1945

Shared with 2 other laureates.

Age that year

39years

Born in 1906.

Headline credited impact

20–50million lives saved

Lives saved by penicillin since it entered medical use. How it was built

Sources cited

15

Fact-checked September 24, 2026.

  • He landed in England on 2 April 1933, weeks after Hitler took power, reportedly with £10; his mother and sister stayed in Berlin and were killed in the Holocaust.
  • Chain was first author of the August 1940 Lancet paper showing that concentrated penicillin saved mice from deadly bacterial infections.
  • Before penicillin was ever given to a patient, Chain and Edward Abraham described a bacterial enzyme that destroys it, an early warning of drug resistance.
  • As a young man he gave piano recitals and wrote music criticism for a Berlin newspaper, and seriously weighed a concert career before choosing chemistry.
  • In 1965 he gave a talk titled 'Why I am a Jew' at a World Jewish Congress conference, and he gave many lecture fees to a London synagogue and Jewish charities.

The breakthrough

Turning penicillin from a mould curiosity into a medicine (1939-1943)

In 1928 Alexander Fleming noticed that a mould called Penicillium killed bacteria growing near it. He named the substance penicillin, but it was fragile and he could not purify it, so for a decade it stayed a laboratory curiosity. In 1938 Chain, a young biochemist in Howard Florey's department at Oxford, read Fleming's paper and proposed a closer look. Chain's job was the chemistry, and it was hard. Penicillin fell apart in acid, in alkali and in heat, and the mould juice held only a trace of it among many impurities. Working with Edward Abraham and Norman Heatley, Chain found that penicillin survived only in a narrow middle range of acidity, that it could be moved from the broth into a solvent and back into water, and that it could be dried in the cold without being destroyed. It was like lifting a snowflake out of a muddy puddle without letting it melt. In May 1940 the team's concentrated extract saved mice injected with deadly streptococci, while untreated mice died overnight. Their August 1940 paper in The Lancet, with Chain as first author, showed that penicillin could cure infections in animals without poisoning them. Chain and Abraham then argued that penicillin's core is an unusual ring of four atoms, the beta-lactam ring, an idea that Dorothy Hodgkin's X-ray work confirmed in 1945. Knowing that shape later helped chemists design new penicillins.[3],[4],[5],[7]

“The success of this work has been due to the combined efforts of all the members of our group”
Ernst B. Chain, Nobel Lecture, 20 March 1946, crediting the Oxford chemists who worked with him on the structure of penicillin.[3]

What it meant for humanity

Before penicillin, doctors had few drugs that could stop a bacterial infection once it spread through the body; the new sulfa drugs were the main exception. The Oxford team's work changed that within a few years. In 1941 the United States did not have enough penicillin to treat a single patient. By September 1943 it had enough for all the Allied armed forces, and by 1944 penicillin was in wide use on the battlefields of Europe, treating infected wounds and pneumonia. In 1945 American civilians could get it without restriction. Penicillin also opened the antibiotic era: using similar search and production methods, researchers found streptomycin, erythromycin, vancomycin and many other antibiotics in the 1940s and 1950s. Chain's chemistry mattered beyond the first drug. Structural work by his group and others showed that all penicillins share one core with different side chains. In 1957 scientists at the British firm Beecham, which had sent two researchers to spend a year learning penicillin production at Chain's centre in Rome, identified that core, and Beecham soon learned to make it in bulk; Chain's part in that final step is unclear. Together with John Sheehan's method for attaching new side chains, this opened the way to semisynthetic penicillins such as ampicillin. Chain also argued throughout his life for close ties between government, universities and industry, and he built fermentation pilot plants in Rome and London that trained researchers in antibiotic production. Exactly how many lives penicillin has saved is uncertain. The published estimates we found range from about 200 million to more than 500 million, and neither source explains its method.

  • In 1941 the United States did not have enough penicillin to treat one patient; by September 1943 it had enough for all Allied armed forces.[7]
  • Chain was first author of the August 1940 Lancet paper showing that purified penicillin protected infected animals, a report that set off research on the drug around the world.[4],[7]
  • Chain and Abraham proposed penicillin's beta-lactam ring structure in 1943; Dorothy Hodgkin's X-ray analysis confirmed it in 1945.[3],[4],[5]
  • Semisynthetic penicillins such as ampicillin grew from the penicillin core identified in 1957 by Beecham scientists, whose firm had sent researchers to train at Chain's Rome centre.[4],[5]
  • Oxford's Sir William Dunn School cites an estimate that penicillin has saved over 500 million lives; the Science Heroes project puts it at over 200 million. Neither shows its method.[9],[10]

Impact in numbers

Penicillin was the first antibiotic that could be made in bulk and injected safely, and it opened the antibiotic age. Chain's part was the chemistry: he helped launch the Oxford project, found ways to purify an unstable substance, was first author of the 1940 paper showing it cured infections in animals, and helped show the beta-lactam ring at its core. We record one claim, lives saved by penicillin, using published totals of 200 million to over 500 million. Neither total comes with a published method, so we mark it low confidence, and we credit Chain with only 10%, because Fleming's discovery, Florey's leadership, Heatley's extraction work and the huge Anglo-American production effort were all essential. We put no number on harms: resistance deaths reflect how all antibiotics are used, and there is no reliable global count of fatal penicillin allergies. His Rome and London fermentation centres also trained researchers in antibiotic production.

HealthFundamental science

Each number is the laureate’s credited share of a real-world outcome, cumulative to 2025. The whole outcome, the share of credit, and the reasoning are shown so you can check the arithmetic. Outcomes shared with other laureates are counted once on the impact page.

  • Low confidenceDirectSourced totalHealth

    Lives saved by penicillin since it entered medical use

    20–50

    million lives saved, credited share

    That is 10% of 200–500 million lives saved since 1942.

    How this number was built

    Whole outcome: lives saved by penicillin since clinical use began in the early 1940s. Low 200M rounds down the Science Heroes penicillin figure of over 203M (listed on its Florey page); high 500M is the University of Oxford Dunn School's statement that over 500M lives have been saved. Neither source publishes its method, so confidence is low. Share 0.10: Fleming found the mould's effect in 1928 (about 0.15); Florey conceived and led the Oxford programme and trials (about 0.2); Chain proposed and led the biochemistry, purification and structure work (0.10); Heatley, Abraham and the rest of the team (about 0.1); US and UK industry and government, whose fermentation scale-up made mass supply possible, plus later drug developers (about 0.45). Credited to Chain: 0.10 x 200M-500M = 20M-50M lives.[4],[7],[9],[10]

    Sources: Science History Institute; US Centers for Disease Control and Prevention (via PubMed Central); Sir William Dunn School of Pathology, University of Oxford; Science Heroes

The double edge

Penicillin's harms come mostly from how the world has used antibiotics, not from Chain's conduct. Bacteria fought back quickly. In December 1940, before penicillin had been given to any patient, Chain and Abraham reported an enzyme that some bacteria use to destroy it, an early warning of resistance. Decades of heavy and careless antibiotic use have since bred resistant germs: a 2022 Lancet study estimated that 1.27 million deaths in 2019 were directly attributable to drug-resistant bacteria. Penicillin can also cause allergic reactions, and a 1968 review in the WHO's Bulletin found fatal allergic shock in about 1.5 to 2 of every 100,000 treated patients. Chain's own career was marked by bitter disputes. He clashed often with Florey, and he urged that penicillin be patented; Florey refused on ethical grounds. Merck and a US government scientist later patented production methods, and Britain ended up paying royalties to use them.

  • Moderate

    Antibiotic resistance

    Chain and Abraham found in 1940 that some bacteria make an enzyme, penicillinase, that destroys penicillin. Resistance spread as antibiotics were overused. A 2022 Lancet study estimated 1.27 million deaths in 2019 directly attributable to resistant bacteria, and 4.95 million deaths associated with them. This burden reflects the use of all antibiotics, not penicillin alone.[8],[11],[14]

  • Minor

    Rare but fatal allergic reactions

    Allergy is penicillin's most common serious side effect. A 1968 review in the Bulletin of the World Health Organization estimated that fatal anaphylactic shock follows about 0.0015-0.002% of treatments, roughly 1.5 to 2 deaths per 100,000 treated patients; a WHO expert committee said most such deaths could be prevented.[12]

  • Minor

    Patent and credit disputes

    Chain, used to German practice, pressed for a patent on penicillin. Florey refused, believing a life-saving drug should not be patented, and Chain resented the decision for years. Merck and a US Department of Agriculture scientist later patented production methods, and Britain ended up paying royalties. Disputes over credit strained relations within the Oxford team and are still debated.[4],[6],[7]

Against the odds

Chain grew up in a Jewish family in Berlin that fell on hard times: his father died in 1919, and in the inflation that followed his mother had to take in lodgers. He finished his chemistry degree in 1930 and was doing enzyme research at the Charité hospital when Hitler took power in January 1933. Seeing no future in Germany for a Jewish scientist, he left within about two months, landing in England on 2 April 1933. Five days later a new Nazi law began pushing Jews out of Germany's civil service, which included state universities and hospitals. He arrived alone with little money, relied at first on help from a Jewish refugee committee and a London synagogue, and needed Home Office permission to stay. He sent what money he could to his mother and sister in Berlin and tried to get people in authority in Britain to see the Nazi attacks on 'non-Aryan' scholarship then appearing in Germany. His mother and sister never got out. The last news of them dates from 1942 and early 1943, and both were killed in the Holocaust. Even after the Nobel Prize, borders stayed hard for him: in 1951 the United States refused him a visa, possibly because he had overseen penicillin plants in Czechoslovakia.

  • 1919

    Poverty

    His father's death in 1919 and Germany's post-war inflation left the family in debt; his mother let rooms in their home to get by.[5],[6]

  • 1933

    Persecution

    Convinced that a Jewish scientist had no future under the Nazis, he left for England, arriving on 2 April 1933. Five days later the Law for the Restoration of the Professional Civil Service began removing Jews from state universities and hospitals.[2],[5],[6],[13]

  • 1933

    Exile

    He arrived in Britain alone with little money, relied on financial help from the Jewish Refugees Committee and the Liberal Jewish Synagogue, and needed Home Office permission to stay until his time limit was lifted in 1936.[6],[15]

  • 1942

    Family killed

    His mother, Margarete, and sister, Hedwig, stayed in Berlin. The last news of them dates from 1942 and early 1943, and both were killed in the Holocaust.[4],[5],[6]

  • 1951

    Other

    In 1951 the US State Department refused him a visa without giving a reason; many believed his postwar trip to oversee penicillin plants in Czechoslovakia was the cause.[5]

Jewish background

Both parents JewishReligiously observant

Chain was born in Berlin to Michael Chain, a chemist and industrialist who had emigrated from Russia, and Margarete Eisner; both parents were of Jewish descent. He left Germany in 1933 because he saw no future there as a Jewish scientist. His mother and his sister Hedwig stayed behind and were killed in the Holocaust. The catalogue of his papers describes Jewish faith as central to his life. He married Anne Beloff at Hampstead Synagogue in 1948, gave many lecture fees to a London synagogue and other Jewish charities, served as a governor of the Weizmann Institute of Science, championed Jewish education for children, and in 1965 spoke on 'Why I am a Jew' at a World Jewish Congress conference.[4],[5],[6],[15]

Key dates

  1. June 19, 1906

    Born in Berlin, Germany, to Michael Chain, a Russian-born Jewish chemist and industrialist, and Margarete Eisner.[1],[2],[5]

  2. 1930

    Graduates in chemistry from Friedrich-Wilhelm University, Berlin, and begins three years of enzyme research at the Charité hospital.[2],[5]

  3. April 2, 1933

    Lands in England after the Nazis take power, leaving his mother and sister behind in Berlin.[2],[6]

  4. 1935

    After a Cambridge PhD under Frederick Gowland Hopkins, joins Howard Florey's Sir William Dunn School of Pathology at Oxford to build its biochemistry section.[2],[5]

  5. May 25, 1940

    Purified penicillin protects mice infected with deadly streptococci, while untreated mice die overnight.[4]

  6. August 24, 1940

    Chain, Florey and colleagues publish 'Penicillin as a chemotherapeutic agent' in The Lancet.[4],[7]

  7. 1942

    His mother and sister, still in Berlin, are last heard of in 1942 and early 1943; both were killed in the Holocaust.[4],[5],[6]

  8. October 1943

    The Oxford group proposes the beta-lactam structure of penicillin, argued for by Chain and Abraham; Dorothy Hodgkin's X-ray work confirms it in 1945.[3],[4],[5]

  9. 1945

    Shares the Nobel Prize in Physiology or Medicine with Alexander Fleming and Howard Florey for the discovery of penicillin and its curative effect.[1]

  10. October 7, 1948

    Marries biochemist Anne Beloff at Hampstead Synagogue and moves to Rome to direct a new research centre for chemical microbiology.[2],[6]

  11. 1957

    Scientists at Beecham, which had sent researchers to train at his Rome centre, identify the penicillin core, opening the way to semisynthetic penicillins.[4],[5]

  12. 1964

    Returns to Britain to head a new biochemistry department at Imperial College London, complete with a fermentation pilot plant.[4],[5]

  13. 1965

    Speaks on 'Why I am a Jew' at the World Jewish Congress's second Conference of Intellectuals.[6]

  14. August 12, 1979

    Dies in County Mayo, Ireland, where he had built a home in Mulranny.[1],[15]

Sources

  1. 1.Ernst B. Chain - Facts · NobelPrize.org (Nobel Prize Outreach)
  2. 2.Ernst B. Chain - Biographical · NobelPrize.org (from Nobel Lectures, Physiology or Medicine 1942-1962, Elsevier, 1964), 1964
  3. 3.The chemical structure of the penicillins (Nobel Lecture, 20 March 1946) · NobelPrize.org, 1946
  4. 4.Howard Walter Florey and Ernst Boris Chain · Science History Institute
  5. 5.Chain, Ernst Boris (Complete Dictionary of Scientific Biography entry by John Patrick Swann; World of Microbiology and Immunology entry) · Encyclopedia.com
  6. 6.Catalogue of the papers and correspondence of Sir Ernst Boris Chain FRS (CSAC 92/3/83), compiled by Jeannine Alton and Julia Latham-Jackson · Centre for Scientific Archives (originally Contemporary Scientific Archives Centre; papers held at the Wellcome Collection), 1983
  7. 7.The Discovery of Penicillin - New Insights After More Than 75 Years of Clinical Use, by Robert Gaynes (Emerging Infectious Diseases 23(5): 849-853) · US Centers for Disease Control and Prevention (via PubMed Central), 2017
  8. 8.An Enzyme from Bacteria able to Destroy Penicillin, by E.P. Abraham and E. Chain (Nature 146, 837) · Nature, 1940
  9. 9.Our History (Centenary) · Sir William Dunn School of Pathology, University of Oxford
  10. 10.Florey, Howard - Penicillin! · Science Heroes
  11. 11.Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis, by Antimicrobial Resistance Collaborators (Lancet 399: 629-655) · The Lancet (via PubMed), 2022
  12. 12.Nature and extent of penicillin side-reactions, with particular reference to fatalities from anaphylactic shock, by O. Idsoe, T. Guthe, R.R. Willcox and A.L. de Weck (Bulletin of the WHO 38: 159-188) · Bulletin of the World Health Organization (via PubMed Central), 1968
  13. 13.Law for the Restoration of the Professional Civil Service · United States Holocaust Memorial Museum, Holocaust Encyclopedia
  14. 14.The unseen enemy: navigating antimicrobial resistance · NobelPrize.org (Nobel Prize Outreach)
  15. 15.Who was Sir Ernst Chain? · Connaught Telegraph, 2017

Fact-checked on September 24, 2026 by a separate AI fact-checking pass that re-opened the sources, with 8 corrections made. How we check

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