Microbiology is the study of microorganisms such as bacteria, fungi, protozoa, microscopic algae, and viruses. It is about all of those tiny entities that can cause so much trouble to us in the form of disease but can also do so much good work in ecosystems, and even inside the human body itself, as anyone who has ever been immunized against a disease or eaten a live yoghurt will know.
By its very nature microbiology had limits to when it could practically begin as a discipline, with the objects of study being so small that it was only with the invention of the microscope that anything could be observed. But when the technology arrived it opened up a new vista of understanding as the early microbiologists were overwhelmed by a new menagerie of wonderful little entities.
For many years prior to the first observations of microorganisms in the 17th Century they had been hypothezised to exist. The Roman Marcus Terentius Varro, in On Agriculture as far back as the first century BC, warned people to avoid living near swamps because of disease causing creatures that cannot be seen by the naked eye. In 1020, Avicenna, in The Canon of Medicine, hypothesized that infections were caused by bodily secretions contaminated by foreign bodies.
Numerous other speculations were made over the years, but microbiology could not fully begin until in 1676 Antonie van Leeuwenhoek made a single lens microscope that allowed him to actually observe microorganisms. Although some would argue that Robert Hooke made the first microbiological observation when observing fruiting bodies in molds in 1665.
After 1676 the race was on both to improve the microscopes and techniques that were available for observation and to make as many new discoveries as possible, a race that continues to this day. Bacteriology, a sub-discipline of microbiology, was founded by Ferdinand Cohn in the 19th Century, and it was him that would be the first to provide a taxonomy for bacteria.
Medical microbiology was also founded in the 19th Century by Louis Pasteur and Robert Koch. Pasteur made advances in food preparation such as pasteurization and also provided vaccines for diseases including anthrax and rabies. Koch was to make the vital advance in theory that is the germ theory of disease. This is the idea that particular diseases are linked to particular microorganisms.
But a more general microbiology, not tied to medicine, was created in the late 19th and early 20th Century by Martinus Beijerinck and Sergei Winogradsky. It was Beijerinck who was to be the first to discover viruses and to develop the basics of virology through the study of the Tobacco Mosaic Virus, and also to develop the techniques of enrichment culture. Winogradsky, meanwhile, developed the idea of chemolithotrophy, and was the first to find nitrifying and nitrogen fixing bacteria.