Imshenetskii, Aleksandr Aleksandrovich

Born Dec. 26,1904 (Jan. 8, 1905), in Kiev. Soviet microbiologist. Academician of the Academy of Sciences of the USSR (1962; corresponding member, 1946).

Imshenetskii graduated from the University of Voronezh in 1926. In 1930 he began working at the Institute of Microbiology of the Academy of Sciences of the USSR, becoming its director in 1949. His principal works are on the morphology and ecological physiology of microorganisms and their role in the cycle of substances in nature. He established the distinction between the nuclear apparatus of bacteria and the cell nuclei of higher organisms. He snowed that thermophile bacteria reproduce more rapidly than mesophilic ones and possess enzymes that retain their activity at 90°C. He proved (1954) the possibility of oxidizing ammonia with acellular preparations from the cells of nitrifying bacteria. While studying the decomposition of cellulose by microorganisms, he established that under aerobic conditions cellulose is decomposed predominantly by myxobacters. Imshenetskii studied the principles of variation of microorganisms under the influence of mutagens and the physiology of the formed mutants, including those of practical interest. He obtained polyploid cultures of the yeasts Candida and of some bacteria. He also investigated the enzymes of microorganisms, including fibrinolytic (thrombus-dissolving) enzymes and cholesterol oxidase.

Imshenetskii is the author of works on space biology (the effect of high vacuum and radiation on terrestrial microorganisms, methods of detecting life outside the earth, and microbiological analysis of meteorites). A recipient of the Louis Pasteur Medal in 1955, he has also been awarded the Order of Lenin, two other orders, and various medals.