Before the microscope, ideas about invisible agents that caused or influenced life processes were speculation, not science. One man, Abbas Ibn Firnas, experimented with lenses in Cordoba
around 840 C.E., but his work was lost. A light microscope was first made in the Netherlands in about 1595, possibly by Hans Lippershey, and soon afterwards the science of microbiology began.
The classical Greeks and Romans had wondered about infinitely small particles. Democritus, a Greek, theorized that the world was made of building blocks too small to see. He was followed by Lucretius, a Roman, who also believed in an invisible world, but who speculated that life arises spontaneously, and started science on a long wrong track. About 1025 C.E. Ibn Sina (Avicenna), a Persian, hypothesized the existence of microorganisms.
Antonie van Leeuwenhoek is considered the father of microbiology, however, mostly because of his patient proficiency with the microscope. A Dutch linen merchant born in 1632, not rich or highly educated, speaking no Latin nor any language but Dutch, he ground and polished his own lenses. He used simple hand-made microscopes, more primitive than many available in his day, but with them he was the first person to see bacteria. He also discovered, and precisely described, protists, blood cells, nematodes, and rotifers. His work was painstaking, and he sent careful reports to the Royal Society of London for 50 years. They made him a full member, although he never attended a meeting. On the day he died, he made observations through his microscope.
Building on his work, Ferdinand Julius Cohn (1828-1898) was a botanist who created the first classification of bacteria. Louis Pasteur (1822-1895) famously invented pasteurization, and also created vaccines against anthrax and rabies. Robert Koch (1845-1910) isolated he microorganisms that cause cholera and tuberculosis, and designed Koch's postulates, a series of rules for establishing that a specific organism is the cause of a certain disease. These three men are considered to have founded bacteriology, now a discipline of microbiology.
Martinus Beijerinck (1851-1931) discovered viruses in 1898. He also established the method for culturing microbes with differing physiologies. Sergei Winogradsky (1856-1953) discovered the lithotrophs (microorganisms that get nourishment from minerals), as well as nitrogen-fixing and nitrifying bacteria.
Penicillium notatum is a fungus with a toxic effect on bacteria. Sir Alexander Fleming noticed this in 1928, and it became the first antibiotic. Sir Alexander himself also noticed that bacteria would develop resistance to the drug if it was used too widely or in insufficient quantities.
In the 1930s, the first electron microscope came into use. It was co-invented by Max Knoll and Ernst Ruska, who later won a Nobel Prize for his part in the project. These instruments can reveal details about 1 to 5 nanometers in size (a nanometer is about one billionth of a meter), in an image with great depth of field: the peaks and valleys of the specimen remain in sharper view than with a light microscope. Electron microscopes also can provide information about the chemical composition of a specimen. They can magnify at least 250 times better than the best light microscopes.
The discovery of the role of DNA and RNA in the transmission of genetic information was a milestone for microbiology. Francis Crick, James Watson, and Maurice Wilkins, all molecular biologists, shared a Nobel Prize for their work.
However, when Crick, Watson, and Wilkins explored the structure and function of DNA in 1953, X-ray crystallography was a chief tool. It is still in use to illuminate the structure of large molecules. Dorothy Crowfoot Hodgkin pioneered this technique, which interprets patterns thrown out by rotating crystals to reveal their internal makeup. She would later win a Nobel Prize for her work.
Today, the techniques of microbiology are widely used in the commercial production of such traditional fermented products as yogurt, tofu, wine, and beer. Somewhat similar techniques produce amino acids, biopolymers, proteins and enzymes for industrial, medical, and scientific applications. At the same time, the search continues for the tiniest clues about the universal and particular mechanisms of life. All of this is built on a foundation of the hard work and hard-won insights of the pioneers of microbiology.