Pasteur's fermentation experiments disprove spontaneous generation and establish that microorganisms drive specific chemical and biological processes — the conceptual foundation germ theory is built on.

Pasteur takes up the pébrine silkworm disease crisis threatening the French silk industry and is credited with resolving it — the same episode at the center of his priority dispute with Béchamp (see Origins).

Robert Koch demonstrates that Bacillus anthracis causes anthrax — the first rigorous proof that a single, specific microbe produces a single, specific disease.

Koch identifies Mycobacterium tuberculosis as the cause of tuberculosis, then the deadliest disease in Europe.

Koch formalizes his postulates — four criteria for proving a microbe causes a disease — giving germ theory a repeatable, testable method that becomes its methodological backbone.

Pasteur's rabies vaccine is administered to a human for the first time and succeeds publicly and dramatically, triggering a worldwide fundraising campaign in his name.

That campaign funds the founding of the Pasteur Institute in Paris — a permanent, well-resourced institution dedicated to germ-theory research, with no terrain-theory equivalent.