How did Louis Pasteur, Robert Koch, and Ferdinand Cohn advance the study of bacteria?

Louis Pasteur, Robert Koch, and Ferdinand Cohn were pivotal in establishing bacteriology as a rigorous scientific discipline.

• Louis Pasteur advanced the field by demonstrating that fermentation is caused by microorganisms and disproving the theory of spontaneous generation. His work laid the foundation for germ theory, which posits that diseases result from external microbial invasion, and he pioneered the development of vaccines for diseases like anthrax and rabies.4

• Ferdinand Cohn was among the first to classify bacteria systematically based on morphology and physiological traits. He discovered endospores, explaining how bacteria survive extreme heat, which further refuted spontaneous generation. He also provided critical support to Koch, publishing his foundational research in his journal, Beiträge zur Biologie der Pflanzen.1

• Robert Koch perfected pure-culture techniques and established Koch’s postulates, a set of criteria to prove a specific microorganism causes a specific disease. His meticulous study of the anthrax life cycle provided the first definitive proof of a causal link between a microbe and a disease.23