22 How the Microscope Advanced Microbiology
While it is unclear who exactly invented the microscope, a Dutch cloth merchant named Antonie van Leeuwenhoek (1632–1723) was the first to develop a lens powerful enough to view microorganisms. In 1675, using a simple but powerful microscope (Figure 7.3), Leeuwenhoek was able to observe single-celled organisms, which he described as “animalcules” or “wee little beasties,” swimming in a drop of rainwater. From his drawings of these little organisms, it is now known he was looking at bacteria and protists.
Two hundred years after van Leeuwenhoek got his first glimpse of microorganisms, the “Golden Age of Microbiology” spawned a host of new discoveries between 1857 and 1914. Two famous microbiologists, Louis Pasteur and Robert Koch, were especially active in advancing the understanding of the unseen world of microorganisms (Figure 7.4). Pasteur, a French chemist, showed that individual microbial strains had unique properties and demonstrated that fermentation is caused by microorganisms. He also invented pasteurisation, a process used to kill microorganisms responsible for spoilage, and developed vaccines for the treatment of diseases, including rabies in animals and humans. Koch, a German physician, was the first to demonstrate the connection between a single, isolated microbe and a known human disease and discovered many new bacteria including the bacteria that cause anthrax (Bacillus anthracis), cholera (Vibrio cholerae) and tuberculosis (Mycobacterium tuberculosis).
As microbiology has developed, it has allowed the broader discipline of biology to grow and flourish in previously unimagined ways. Much of what is known about human cells comes from the understanding of microorganisms and many of the tools used today to study cells and their genetics derive from work with microorganisms.
Microbiology is a broad term that encompasses the study of all diverse types of microorganisms. But in practice, microbiologists tend to specialise in one of several subfields. For example, bacteriology is the study of bacteria; mycology is the study of fungi; protozoology is the study of protozoa; parasitology is the study of helminths and other parasites; and virology is the study of viruses. Immunology, the study of the immune system, is often included in the study of microbiology because host–pathogen interactions are central to the understanding of infectious disease processes. Microbiologists can also specialise in certain areas of microbiology, such as clinical microbiology, environmental microbiology, applied microbiology or food microbiology.
