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Long Road. By 1915, when he graduated, Selman Waksman already had one toe on the threshold of a great discovery: he had found in the soil a microbe which he has since named Streptomyces griseus.* He had no reason to suspect that it was a life-saving drug. A year later he wrote his master's thesis on this and related microbes. He was on the road to streptomycin, but it would be almost 30 years before he reached the end of the road.
Meanwhile, Selman married Deborah Mitnick, a girl from the old country who had come to join her brother in the U.S. Back at Rutgers in 1918 as a lecturer in soil microbiology, after getting his Ph.D. at the University of California, Waksman worked mostly on the soil problems of farmers. But he began asking himself a question which is still far from answered: What do microbes do to the soil, to each other, and ultimately to man?
Dust to Dust. Long before Waksman began his work on soil, scientists had noted that if a diseased body is buried, the point of burial does not become a plague spot. Instead, something in the soil destroys the germs. It was proved that micro-organisms were doing the police job. But how, exactly, did one microorganism destroy another? By eating it? Beating it to the feed trough? Chemical warfare?
Says modest Dr. Waksman: "I get students from all over the world, and sometimes I learn more from the student than he learns from me." Such a student came to Waksman in 1924 to work for his Ph.D.: a young (23) Frenchman named René Jules Dubos. Waksman turned Dubos loose on the activities of microbes in reducing plant fibers to humus.
Brilliant young Dubos went to work on a fantastic idea which, like many great ideas, was almost laughably simple: Why not feed disease germs to soil micro-organisms and see which species thrived on the diet?
Dubos took samples from patches of soil and noted which micro-organisms were present in them and how many of each kind. Then he made a brew of pneumonia bacteria and poured it on material from the patches. He repeated the experiment many times, watching for changes in the soil's microscopic population. Some of the organisms thrived on the strange diet, indicating that they might destroy pneumonia bacteria. Dubos made cultures of the hardy fighters and tested them against various disease-causing organisms.
By this method and refinements of it, he at last found, in a sample of cranberry bog soil sent to him by Waksman, an organism from whose cultures he separated an active fraction that he named gramicidin. It killed or halted many disease bacteria, but it was dangerous for internal use.
In spite of such failings, gramicidin touched off a chain reaction. Dubos announced its discovery in 1939. A group of British researchers heard about it and recalled Alexander Fleming's Penicillium notatum. The substance it secreted is penicillin. Ripples of excitement spread through the world's biological laboratories.