Why was Robert Koch's anthrax research important to germ theory?

Robert Koch’s research on anthrax was a landmark achievement for germ theory because it provided the first convincing proof of a definite causal relationship between a specific microorganism and a specific disease.1

While earlier scientists had observed bacteria in the blood of infected animals, Koch’s work was unique in its completeness. Through meticulous laboratory experiments, he discovered the anthrax life cycle, including the formation of dormant spores. This discovery explained how the disease could recur in pastures long after infected animals had been removed, as the spores remained viable for years before developing into the rod-shaped bacteria that cause the illness.1

By demonstrating the full life cycle of the organism and perfecting techniques to cultivate it outside the body, Koch established a rigorous scientific standard for identifying pathogens. This work laid the foundation for his later development of Koch’s postulates, a set of criteria that remains a cornerstone of microbiology for proving that a particular microbe is the cause of a specific disease.1234