Final answer:
Louis Pasteur cultured the bacterium responsible for milk spoilage in 1856 while studying microbial fermentation, leading to the germ theory of disease and the development of pasteurization.
Step-by-step explanation:
The bacterium responsible for milk spoilage was cultured by the French chemist Louis Pasteur. In 1856, while investigating the causes of beer and wine spoilage, Pasteur discovered the role of microorganisms in fermentation. His research demonstrated that airborne microbes were responsible for fermentation and food spoilage, laying the groundwork for the germ theory of disease. Pasteur's experiments, including his famous swan-neck flask experiments, proved that microorganisms from the air caused fermentation, countering the idea of spontaneous generation where food spoilage was once thought to arise spontaneously without the need for living organisms.Furthermore, Pasteur's work in microbiology continued to have a profound impact on food safety. His development of pasteurization, a process that eliminates pathogenic microbes in food and beverages, helped prevent foodborne illnesses and saved countless lives. This method is widely used today in the dairy industry to extend the shelf life of milk and other dairy products by destroying the microbes that cause spoilage and diseases.