Final answer:
Louis Pasteur is best known for formulating the germ theory of disease, conducting experiments to prove that disease is caused by microorganisms and developing the technique of pasteurization.
Step-by-step explanation:
Louis Pasteur is best known for formulating the germ theory of disease. He conducted experiments that provided evidence that disease is caused by microorganisms, disproving the concept of spontaneous generation and proving that microbes are responsible for putrefaction. Additionally, Pasteur developed the technique of pasteurization to make food safe and created effective vaccines against diseases like anthrax.