Salvador Luria

Salvador Luria was an Italian-American microbiologist who, together with Max Delbruck, carried out the Luria-Delbruck experiment in 1943, a landmark study demonstrating that mutations in bacteria arise randomly and spontaneously rather than as a direct response to the specific environmental pressure that later reveals them, such as exposure to a virus or an antibiotic. The experiment used statistical analysis of bacterial cultures exposed to a bacteria-infecting virus to distinguish between two competing hypotheses about how resistant bacterial strains arise, and its result became a foundational piece of evidence supporting the modern understanding of mutation and natural selection in microorganisms. Luria, who had fled fascist Italy in 1938, spent most of his career in the United States, including long periods at Indiana University and the Massachusetts Institute of Technology, where he mentored a number of younger scientists, including James Watson. Luria shared the 1969 Nobel Prize in Physiology or Medicine with Max Delbruck and Alfred Hershey for their discoveries concerning the replication mechanism and genetic structure of viruses.