Louis Pasteur did not disprove the theory of biogenesis; he disproved spontaneous generation. The theory of biogenesis was what Louis Pasteur developed after his experiments showed that spontaneous generation did not occur.
Louis Pasteur disproved the theory of spontaneous generation with his famous swan-necked flask experiment. He placed nutrient broth inside of a glass flask that had a long, curved neck so that any bacteria or particles from the air would become trapped in the neck. This broth was then boiled to sterilize it. Although the flask remained open to the air, nothing grew in the broth. However, if the neck of the flask were cut off so that particles in the air could fall straight down into the broth, fungi and bacteria began to grow in the broth within a day or two.
This experiment showed that life did not spontaneously generate in broth and provided evidence that sterilized foods in closed containers would remain sterile until the containers were opened. Louis Pasteur used these findings to come up with the law of biogenesis, which stated that life must come from other life.
However, some of the confusion associated with what Louis Pasteur did or did not disprove is associated with the term "biogenesis," which has been used in the past to refer both to "life originating from other life" and "life originating from non-living materials."