Bacillus anthracis
Robert Koch is widely known for his work with anthrax, discovering the causative agent of the fatal disease to be "Bacillus anthracis". He published the discovery in a booklet as "Die Ätiologie der Milzbrand-Krankheit, Begründet auf die Entwicklungsgeschichte des Bacillus Anthracis" ("The Etiology of Anthrax Disease, Based on the Developmental History of Bacillus Anthracis") in 1876 while working at in Wöllstein. His publication in 1877 on the structure of anthrax bacterium marked the first photography of a bacterium. He discovered the formation of spores in anthrax bacteria, which could remain dormant under specific conditions. However, under optimal conditions, the spores were activated and caused disease. To determine this causative agent, he dry-fixed bacterial cultures onto glass slides, used dyes to stain the cultures, and observed them through a microscope. His work with anthrax is notable in that he was the first to link a specific microorganism with a specific disease, rejecting the idea of spontaneous generation and supporting the germ theory of disease.