Buchner's cell-free fermentation

In 1896 and 1897 the German chemist Eduard Buchner, at the University of Tubingen, was trying to make yeast extracts for medical use. He ground yeast with sand, squeezed out the juice and, to preserve it, mixed in large amounts of sugar, as in jam. The mixture bubbled, producing carbon dioxide and alcohol. Fermentation was happening with no living cells present. He reported the result in 1897 and named the active agent zymase. Buchner received the Nobel Prize in Chemistry in 1907.¹²

Louis Pasteur had argued in the 1850s and 1860s that fermentation cannot be separated from the life of the yeast cell, a view tied to the older belief called vitalism, that living matter works by special forces. Friedrich Wohler's synthesis of urea in 1828 had already cracked the barrier between organic and lifeless chemistry, and other chemists had long suspected that fermentation was ordinary chemistry. The word enzyme, meaning in yeast, had been proposed by Wilhelm Kuhne in 1877 for the unorganized ferments, but until Buchner nobody had shown that the chemistry of life could run outside the cell.³

The experiment opened biochemistry. Arthur Harden and William Young found around 1905 that phosphate takes part in fermenting sugar, and by the 1930s the steps of glycolysis were mapped. In 1926 James Sumner crystallized the enzyme urease and showed it is a protein. Metabolic pathways such as the Krebs cycle followed. Enzymes are now used in detergents, cheese making, brewing and medical tests, and engineered enzymes won a share of the 2018 Nobel Prize in Chemistry.³⁴