Buchner: alcoholic fermentation by cell-free yeast juice, and zymase
The discovery that cell-free yeast juice does what living yeast does: it turns sugar into alcohol and carbon dioxide. The active agent is not indissolubly tied to a whole cell.
The task was applied. The German Eduard Buchner was extracting yeast cell fluid for the therapeutic research of his brother Hans. Yeast was ground with quartz sand and kieselguhr and pressed out, and to preserve the juice it was mixed with sugar, whereupon the sugar unexpectedly began to ferment. Published in 1897; Buchner named the active agent zymase.
This eliminated the distinction between soluble enzymes acting outside the cell and 'ferments' tied to the structure and life of the cell: life and fermentation turned out not to be bound to each other for good, and Liebig's demand that fermentation be explained chemically received a belated confirmation.
Why this date
High. The experiment was made in 1896; three papers appeared in 1897, among them the programmatic "Alkoholische Gährung ohne Hefezellen", Berichte der deutschen chemischen Gesellschaft 30 (1897), 117-124 (bibliographic details from H. C. Friedmann's translation reprinted in Cornish-Bowden's collection). Nobel Prize in Chemistry 1907.
What it grew from
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Liebig: fermentation is transmitted decomposition, not the work of a living thing
influenced · Confidence: medium
The mechanist line, of which Schriefers names Liebig the exponent, survived down to Buchner and was vindicated in substance precisely by his result: fermentation turned out to be a chemical, enzymatically catalysed process not bound for good to the life of the cell. Liebig's own mechanism was not revived.
Dispute: The words "Buchner vindicated Liebig" are not stated outright by any of the historians read. Schriefers places the discovery in the frame of the mechanist-vitalist dispute and names Liebig the exponent of the mechanists, but does not assert that the theory of 1839 gave rise to the work of 1897. Hence medium confidence, and the link is drawn as influence rather than as a direct improvement: Buchner did not improve Liebig's mechanism, he confirmed the side of the question opposite to Pasteur's.
Link sources
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026
Between 1830 and 1860, prior to Buchner's discovery, two theories of fermentation had divided the scientific world into vitalists and mechanists.
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026
Liebig was the exponent of the mechanists.
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026
life and fermentation are not unalterably bound to each other. Instead, fermentation is a chemical, enzymatically catalyzed process.
- James A. Barnett, Frieder W. Lichtenthaler, «A history of research on yeasts 3: Emil Fischer, Eduard Buchner and their contemporaries, 1880-1900», Yeast 18 (4), 363-388 (2001)
the von Liebig-Stahl idea of transmitting motion and Pasteur's belief that fermentation is necessarily produced by living organisms
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026
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Pasteur: fermentation is the physiological work of living cells, from the Bigo factory to the Études sur la bière
influenced · Confidence: high
Buchner removed precisely that part of Pasteur's thesis in which fermentation was declared inseparable from the life of the cell: cell-free juice fermented. The rest of Pasteur's position stood, so the link is drawn as influence and not as the refutation of a dead end.
Dispute: In the text read, Bohley and Fröhlich do not write that the discovery "closed" the Liebig-Pasteur dispute, and they call it "one of the great landmarks in the development of biochemistry" rather than the birth of the discipline. Schriefers is more cautious: for him it is "the turning point for the study of enzymes". The phrase "the beginning of biochemistry" is deliberately kept out of this link.
Link sources
- Peter Bohley, Kai-Uwe Fröhlich, «A Prize-Winning Discovery of 1896: Buchner Provides Evidence of Cell-Free Fermentation», A. Cornish-Bowden, New Beer in an Old Bottle: Eduard Buchner and the Growth of Biochemical Knowledge, Universitat de València, 43-50 (1997)
Pasteur viewed the process as a physiological act closely and inseparably tied to the life processes of yeast cells.
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026
life and fermentation are not unalterably bound to each other. Instead, fermentation is a chemical, enzymatically catalyzed process.
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026
Pasteur's view of the unalterable connection between vitality and fermentation nevertheless found acceptance among the majority of scientists.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- Peter Bohley, Kai-Uwe Fröhlich, «A Prize-Winning Discovery of 1896: Buchner Provides Evidence of Cell-Free Fermentation», A. Cornish-Bowden, New Beer in an Old Bottle: Eduard Buchner and the Growth of Biochemical Knowledge, Universitat de València, 43-50 (1997)
Node sources
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026
Central to Buchner's experimental work are three papers published in 1897, which dealt with his sensational discovery of cell-free fermentation, the turning point for the study of enzymes.
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026
The problem was how to obtain cell fluid, in as pure a state as possible, for therapeutic research.
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008)
This was the problem Buchner attacked anew in 1893 at the suggestion of his brother Hans, who was engaged in the extraction of powerful pathogenic substances from bacteria.
- Herbert Schriefers, «Buchner, Eduard», Complete Dictionary of Scientific Biography (2008) Verified 20 Sep 2026
This eliminated the previously valid distinction between the soluble enzymes, effective outside the cell, and the ferments, whose effectiveness is linked to cell structure and cell activity.
- James A. Barnett, Frieder W. Lichtenthaler, «A history of research on yeasts 3: Emil Fischer, Eduard Buchner and their contemporaries, 1880-1900», Yeast 18 (4), 363-388 (2001)
in 1897, Eduard succeeded in preparing an extract of yeast, completely cell-free, yet able to convert sugar into ethanol and carbon dioxide.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
Further reading
Not evidence: these carry no quotation and support nothing we wrote. They are books and scans to read next.