In 1877, Louis Pasteur noted that some bacteria die when cultured with certain other bacteria, indicating that some bacteria give off substances that kill others; but it will not be until 1939 that Rene Jules Dubos first isolates antibiotics produced by bacteria. Pasteur’s research, which showed that microorganisms cause both fermentation and disease, supported the germ theory of disease at a time when its validity was still being questioned. In his ongoing quest for disease treatments he created the first vaccines for fowl cholera; anthrax, a major livestock disease that in recent times has been used against humans in germ warfare; and the dreaded rabies.