Sex in Bacteria 



Genetic Studies, 1945-1952 



JOSHUA LEDERBERG,* Department of Genetics, 

 University of Wisconsin, Madison 



E. L. TATUM, Department of Biological Sciences, 

 Stanford University, Stanford, California 



For many years bacteria were considered biologically exceptional 

 organisms with no genes, nuclei, or sex, although the recognition of 

 their biochemical similarities to other forms of life constituted one of 

 the main foundations of comparative biochemistry. Over the last 

 decade evidence has accumulated which has led to the satisfying con- 

 clusion that bacteria are not biologically unique but possess genetic 

 and behavior systems more or less analogous to those of other forms, 

 including nuclei, genes, and in certain instances even true sexual 

 mechanisms for recombination of unit characters. 



Historically, this change in our thinking in regard to bacteria 

 stems from the pioneer concepts of Lwoff (1938) and Knight (1936) 

 relating the nutritional requirements of mircooganisms to an evolu- 

 tionary loss of synthetic abilities. If such losses in microorganisms 

 were based on mutation and selection as required by modern concepts 

 of evolution, the capacities for synthesis of essential nutrilites in 

 microorganisms should be determined by genes, which should be 

 subject to mutation, as are most genes in other organisms. Such consid- 

 erations led Beadle and Tatum (1941) to the successful production 

 by irradiation of nutritionally deficient or biochemical mutants in the 

 heterothallic ascomycete Neiirospora, and to the establishment of the 

 genie basis of biochemical reactions leading to the synthesis of amino 

 acids and vitamins. This relation has since been amply substantiated 

 and extended by further work with Neiirospora and other sexual 

 microorganisms (cf. Tatum and Perkins, 1950). 



* Paper No. 528 of the Department of Genetics. This work has been 

 supported by research grants (C-2157) from the National Cancer Institute, 

 National Institutes of Health, Public Health Service, and from the Research 

 Committee, Graduate School, University of Wisconsin, with funds provided 

 by the Wisconsin Alumni Research Foundation. 



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