Gramicidin crystals, 1939
Courtesy of Dr. Rollin D. Hotchkiss
Rene Dubos’ best known scientific achievement was discovery of the first antibiotics that were systematically cultivated from soil bacteria and produced commercially. His search for a microbe that would produce a substance capable for destroying pathogenic bacteria culminated in the isolation of Bacillus brevis, from which he extracted the active soluble principle he called tyrothricin that contains the two substances – gramicidin and tyrocidine – that attack gram-positive organisms. Papers on these antibiotics published between 1939 and 1941 established their structure, antibacterial activity, and clinical efficacy. Dubos provided methods through which other antibiotics came to be discovered.