Final answer:
The invention of the microscope is the event that helped establish the science of microbiology, as it allowed scientists to observe and study microorganisms for the first time.
Step-by-step explanation:
The event that helped establish the science of microbiology was the invention of the microscope. Antonie van Leeuwenhoek was the first to use a microscope to actually observe bacteria in 1675, sowing the seeds for the formal study of microorganisms.
This invention allowed scientists like Louis Pasteur and Robert Koch to further investigate microbes and their roles in disease, leading to the Golden Age of Microbiology.
While the discovery of penicillin and the first use of antibiotics were pivotal in microbial research and treatment of infections, the very framework for understanding and researching microorganisms stemmed from the ability to see them, which was made possible by the invention of the microscope.