Virtanen, Artturi Ilmari

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(b. Helsinki, Finland, 15 January 1895; d. Helsinki 11 November 1973), biochemistry.

Virtanen, the son of Kaarlo and Serafina Isotalo Virtanen, received his elementary education at the classical lyceum in Viipuri (now Vyborg, R.S.F.S.R.), after which he entered the University of Helsinki. He received the Master of Science degree in 1916 and for a year served as first assistant in the Central Industrial Laboratory in Helsinki, then returned to the university for the doctorate, which he obtained in 1919. Virtanen did work in physical chemistry at Zurich in 1920, in bacteriology at Stockholm in 1921, and in enzymology at Stockholm with Euler-Chelpin in 1923 and 1924. Between 1918 and 1920 he was associated with laboratories for the control of butter and cheese manufacture, and from 1921 to 1931 he was director of the laboratories of the Finnish Cooperative Dairies Association. In 1931 Virtanen became director of the Biochemical Research Institute at Helsinki, a position he held for life. After 1924 he also held academic posts: Dozent at the University of Helsinki and professor of biochemistry at the Technical University in Helsinki, remaining at the latter until 1939. From 1939 to 1948 he was professor of biochemistry at the University of Helsinki. In 1920 he married Lilja Moisio. They had two sons.

Virtanen’s broad scientific background led to his interest in theoretical biochemistry, while his experience in the dairy industry acquainted him with agricultural problems. Throughout his life he combined these interests in work that contributed greatly both to academic biochemistry and to agricultural chemistry.

Virtanen’s first biochemical studies concerned bacterial fermentations. In 1924 he showed the necessity for the presence of cozymase in lactic and propionic fermentations. Convinced that most of the proteins in plant cells were enzymes, he undertook a comparison of protein content and enzyme activity of the cells. His attention was thus drawn to the nitrogenous substances of plants, and in 1925 he began to investigate their production in the root nodules of leguminous plants. Virtanen recognized that during storage much of the nitrogenous material was lost. This fact was of great practical importance in agriculture, since when fodder was kept for a long period, its value as a cattle food decreased.

These considerations led Virtanen to study methods for preserving the quality of fresh fodder. He soon learned that deterioration was slowed in an acid medium. Careful studies of various methods for producing a nutritionally safe degree of acidity that would preserve quality led him to the discovery of the AIV method of fodder storage (the name being taken from his initials). It consisted in treating the fodder with a specific mixture of hydrochloric and sulfuric acids so that silage would rapidly reach a determined degree of acidity. Fodder treated in this way retained nearly its full content of proteins, carotene, and vitamin C for prolonged periods. Cattle fed on it produced milk rich in protein and vitamin A. The method was introduced on Finnish farms in 1929, and its use gradually spread to other countries. For this discovery Virtanen was awarded the Nobel Prize for chemistry in 1945.

While this work was continuing, Virtanen was also pursuing his purely biochemical studied. He found that the synthesis of nitrogenous compounds in leguminous plant roots by bacteria required the presence of a red pigment resembling hemoglobin. He investigated the methods by which plants synthesize vitamins, and in later years he studied the chemical composition of higher plants, isolating a number of new compounds, some of considerable nutritional importance.

In addition to the Nobel Prize, Virtanen received many honorary degrees and medals, and served on the editorial boards of numerous biochemical journals. He was the Finnish representative on the United Nations Commission on Nutrition, and from 1948 to 1963 was president of the Academy of Finland.


Virtanen’s work on nitrogen fixation was summed up in his book Cattle Fodder and Human Nutrition With Special Reference to Biological Nitrogen Fixation (Cambridge, 1938). His account of his studies on the AIV system, as well as his biography, are in Nobel Lectures in Chemistry 1942-1962 (Amsterdam—London—New York, 1964), 71–105.

Henry M. Leicester