Bioc17: girolamo fracastorius proposed that there is something on the earth that can transmit disease. Louis pasteur: he also investigated problems associated with food, the alcohol in wine and beer is the product of microbial activity. Needed direct evidence to link microbes to disease: requires: to isolate a particular microbe and prove that it produces a disease, done by koch and pasteur. Koch: identified and described pathogenic bacteria, pasteur was interested in how to protect animals and humans from disease. Germs and anthrax disease- isolating the causative agent: both koch and pasteur worked on anthrax, louis pasteur, louis pasteur inoculated blood from a sick rabbit (experimental animal model) in neutral urine (culture media). He proved that bacillus anthracis injected in animals can cause disease: he ultimately developed methods to isolate bacteria pure culture. These methods allowed to establish a direct link between the pathogen, bacillus anthracis, and anthrax disease.