SALVADORE EDWARD LURIA (1912-1991)
Acquired Bacterial Resistance to Bacteriophage--Microbial Mutation and Genetics
by King-Thom Chung, Department of Biology, The University of Memphis

Salvadore Luria may be considered a "typical," though brilliant, modern microbiolopgist. Perhaps it should be stated that no two microbiologists are alike, so it is hard to call a truly brilliant microbiologist "typical." But this definition fits well the era in which he lived and which continues today. From the beginning of his career, bacteriology and microbiology were established sciences, unlike the situation with Pasteur, Koch and others in this book. Although Luria started his career in Europe as a doctor, after coming to America, his training and his work were in all in microbiology. He went through all of the progressive "steps" in a typical academic career, from research assistant, to instructor, to assistant and associate professorships. These steps and the initiation of his great work in microbiology took place at the University of Indiana. Then, at the University of Illinois he became a full professor of bacteriology in 1950, moving on to the Massachusetts Institute of Technology (MIT) as professor of microbiology in 1959. During the rest of his life he continued to serve in similar capacities at the forefront of teaching and research in microbiology.

Luria was born to David and Ester (Sacerdote) Luria in Turin, Italy on August 13, 1912. Turin was the capital of the Italian Piedmont region and was an industrial city. His father and mother were Jewish and the family tried to emerge into a higher stratum of society. His father was a timid sort and his mother an uneducated, though witty person, who was able to write some of the essays for her children in school. Salvadore had a brother, Giuseppe, who was 6 years older and a strong influence on his young life. Salvadore was short and not at all athletic in school; the family was opposed to athletics.

After leaving high school he considered whether a career in physics or mathematics, or in medicine would be best. He chose medicine and graduated at the top of his class in 1935. In spite of his excellent academic record these were difficult years for him. He was not attracted to medical practice and was influenced by the rise of Hitler with the threat to Jews. Scientifically, he became aware of the advances in the field of physics. In spite of his concern for his family and his thoughts of remaining as a dutiful medical doctor to support the family, he finally decided to follow his intuition and go to America to study microbiology.

From work as a research follow at the Curie Laboratory and Institute of Radium in Paris he came to America in 1940. His first work was as a research assistant in bacteriology in the Department of Surgery of Columbia University in New York City. During the next few years, Luria made truly "typical" progress in the field of microbiology. At Indiana University he went successfully through the typical college and university positions of instructor, assistant professor, and then associate professor from 1943-1950. During this period he married Zella Hurwitz on April 18, 1945; they had a happy marriage with one son, Daniel.

While a member of the staff of Indiana University he spent a fruitful year at the Cold Spring Harbor Laboratory. Upon his return to Indiana he started a course on the biology of viruses and carried out more teaching, in addition to his research.

In 1950 he accepted the position of full professor at the University of Illinois in Urbana-Champaign. One of us was a member of the University staff at this time and recalls the eminence of Luria, who was highly recognized for his work in the growing field of virology. Numerous professors (including one of the authors of this book) attended his lectures on virology, a rapidly growing field. The University microbiology staff were highly disappointed when Luria left Illinois for a higher salary in a new position recognized his work with bacteriophage (a virus) as well as his work in bacteriology. From the latter part of 1959 until 1972 he served as a professor of microbiology at MIT. In a sense he continued as professor here, as he retired in 1972 and became "Distinguished Professor Emeritus", serving in other capacities while still a MIT professor. From 1972 until 1985 he served as the founder and director of the Center for Cancer Research at MIT. In addition, during his long career as a microbiologist, he lectured at Columbia University, Carnegie Institute, Washington, D.C., Rochester University, and the University of Notre Dame.

He wrote a great deal and served as editor of numerous journals, such as Virology, Assistant Editor of the Journal of Bacteriology, and a sectional editor of Biological Abstracts. He was on the boards of the following journals: Experimental Cell Research, Molecular Biology, and the Journal of Photochemistry and Photobiology.

Luria was the recepient of many honors. He and Max Delbruck, jointly with Alfred Hersey received the Nobel Prize in medicine and physiology in 1969 for work on bacteriophage related to molecular genetics. He was a Guggenheim fellow of both Princeton and Vanderbelt Universities, as well as the Pasteur Institute of Paris. He was president of the American Society for Microbiology from 1967-1968.

One of Luria's graduate students when he taught at the University of Indiana at Bloomington was a thin young man named James Watson. As a graduate student and following graduation, Jim Watson worked with Luria for several years. Watson also became a Nobel prize winner and was noted for his work on the double helix of DNA. Of the many microbial entities on which Luria worked, one of the most important was bacteriophage. Luria, Max Delbruck and Alfred Hershey became known as the "three musketeers of bacteriophages." Luria had a great ability to relate common experiences in life to the laboratory--something every microbiologist needs to understand. One of his great problems with bacteriophage was the ability of the virus to develop resistance. Why did some bacterial hosts develop resistance and not others. What were the statistical patterns involved? The initial answer came to him as he watched a slot machine at a club. He noted that a person might get some money back at times and at other times, nothing at al. He said: "What struck me was that the pattern of slot-machine returns had a lesson to teach me about bacteria---when a billion bacteria are exposed to an excess of bacteriophage, only a few resistant bacteria survive and grow--- was the resistance the result of spontaneous mutation or the exposure to the phage?" The realization of the analogy of the slot machine to clusters of mutant bacteria was an exciting moment for Luria. We see here the human side of pioneering in microbiology. Not all advances occur in the laboratory.

This work of Luria on phage-resistant mutant bacteria opened up bacterial and microbiological genetics, which proved to be a key step in the growth of molecular biology and the fusion of biochemistry and genetics. Another "human side" aspect to Luria's work needs to be considered by all scientists. It is almost a truism of science that all scientists are neat and orderly. We think of all laboratories as being like the spotless and shiny hospital laboratories where blood samples are taken. It is somewhat a surprise to learn that Luria dropped and broke an important and irreplaceable test tube of bacteria infected with bacteriophage. Of this he said : "I have never been a very neat laboratory worker." But the breakage proved to be a blessing in disguise. It would have taken months to start over again with the bacterial species in the broken tube, so he tried a substitute, a Shigella strain, with the bacteriophage and found that this strain worked just as well. These bacteria were also resistant and he stumbled upon the phenomenon of restriction and modification. A big question was how DNA differences were related to resistance of bacteria to bacterial viruses.

In addition to bacterial genetics he also worked upon food poisoning with such bacteria as Salmonella species and strains. He found that this and other bacteria had polysaccharide capsules which were the bases of their pathogenesis in the body and also the key to antibody formation and immunology. Another important "human side" of Luria's pioneering in these fields was expressed by him in this way: "There is nothing I dreaded as much as being without a task and deadline. I needed being under pressure. I enjoyed it. " Today there is great fear of "stress"and "pressure". Actually, we learn from Luria and his outstandiong work that "deadlines" are needed and clear designation work to be done. For this reason, Luria did not avoid teaching responsibilities, but added such work to his research program. At the same time, it is said of him that he was a good husband and father and concerned with family responsibilities.

During his latter years at MIT, as mentioned earlier, he was highly instrumental in organizing a Center for Cancer Research. He was also asked to help organize, for the United States, the National Cancer Program of the National Institutes of Health (NIH). These things were done while he was also working on food poisoning and theoretical problems of restriction and mutation in viruses and bacteria. Balancing his work, his organizational activities and his family concerns must have been difficult, but Luria was not one to complain or to shirk responsibility. Somewhat he seemed to be able to get it all done!

He continued his microbiological career for many years as Distinguished Professor at MIT. During all this time, he had not stopped reading the classics in Greek and Latin. He also started an autobiography and reflected upon his career which had initiated the crucial work of Crick and Watson in discovering the double helix and the basic organization of living matter. He said: "Old age brings a thinking out of one's personal connections. Friends die, leaving behind memories of affinities and congruences. Being old myself, I bemoan their passing, but I do not miss them." What a truly human concept!

Salvadore Edward Luria was a great microbiologist and also a truly great man. He had been a loving husband and a good father. He was one who had opened up new vistas of knowledge and explored the difficulties of the great unknown. The student who is attempting to set up his course in higher education, or who is trying to select a degree or research program can learn much from Luria. "The ability to live in the present has, I believe, served to counterbalance the self-doubt, the sense of personal inadequacy that my youthful experiences and my emotional upsets inevitably generated. I have learned that success depends in great part on concentrating on whatever resources one has for the task at hand, without letting the feeling of inadequacy become an excuse for retreat."

While at MIT he had home in Lexington, Massachusetts. Luria died February 6, 1991. Microbiology was never the same after Salvadore Edward Luria.