Louis Pasteur is known as the father of microbiology. He is renowned for developing the germ theory of disease, creating the process of pasteurization, and for changing the way scientists develop vaccines.
Before Pasteur, people believed the doctrine of "spontaneous generation" - that life spontaneously appeared from non-living matter.
This theory was used to explain why food spoiled and how infection developed. Pasteur disproved this theory.
Pasteur provided the proof for the existence of the germ theory of disease and revolutionized the way we think about human health.