One of the advantages of compound microscopes is the capacity of studying microorganisms, such as bacteria and viruses. The humankind has significantly benefitted from the discipline called microbiology, which could not have been possible without the invention of the microscope. Let’s see how microbiology came into being and the most significant achievements registered to the present day.

What happened before microbiology was invented?

The existence of microorganisms was suspected by some great minds long before the microscope was invented, even though these early precursors of the discipline didn’t have any means to prove their theories.

For instance, “On Agriculture”, a book written by Marcus Terentius Varro during the first century AD, speculated on the existence of individual organisms that can’t be seen with the naked eye, yet manage to affect those working the land. For that reason, the Roman scholar advised against the placement of homesteads next to swampy areas.

Avicenna was another great mind who assumed there had to be microorganisms responsible for the spreading of diseases. In his work published in 1020, “The Canon of Medicine”, he spoke of the contagious nature of tuberculosis and other illnesses.

Other scholars, like Girolamo Fracastoro in 1546, warned about epidemic diseases that could be transferred from one person to another, due to some seed-like entities that were airborne and could enter the body through the mouth and the nose.

However, until the 17th century, when the microscope was invented, no one could verify such claims. And that is why microbiology was not possible until the invention of this particular optical instrument.


The first microorganisms ever observed

During the 17th century, with the advent of the microscope, the first steps toward the creation of a new discipline were taken. Antonie van Leeuwenhoek (1632-1723) is considered the first ever to look at microorganisms through the lenses of a microscope which he made it himself.

He was not the only one with interest in studying these critters that could not be observed with the naked eye. In 1665, Robert Hooke published a book named “Micrographia”, in which he described various plant cells. That was ten years before Leeuwenhoek’s observations on microorganisms.

The connection between microorganisms and their effects

While Hooke and Leeuwenhoek discovered microorganisms in the 17th century, they were not able to establish the impacts these ‘invisible’ living things could have. For instance, they didn’t know that it was the work of bacteria that made food go bad.

A critical advancement was registered by Lazzaro Spallanzani (1729-1799). He discovered that he could sterilize broth by boiling it. That process killed the microorganisms living in the broth which grew only when the substance was left in an uncovered container.

However, Spallanzani could not take his theory further, and it was Louis Pasteur (1822-1895) who finally understood the connection between microorganisms and the diseases they could cause. He used boiled broth which he poured into vessels that were exposed to different conditions so that he could see what happens.

The first sample was stored in vessels that came with a filter that was designed to keep all the particles in the air from entering the growth environment. The second sample was stored in vessels with no filters whatsoever. The air came in contact with the broth through a curved tube to prevent dust particles from passing through.

Both samples were boiled broth, with no microorganisms present at the beginning of Pasteur’s experiment. At the end of this test, both samples continued to be free of microorganisms. This way, Pasteur managed to demonstrate that there was no spontaneous growth of microorganisms. And he found the germ theory to replace the prior one.


The first classification of bacteria

Another big name in the field of microbiology is Ferdinand Julius Cohn (1828-1898). This German biologist was the first to split bacteria into four groups, using the shape of these microorganisms he had observed through the lenses of the microscope. His classification is still used nowadays, and researchers talk of bacteria, as being present in the spherical form, as short rods, threads, and spirals.

Cohn was the researcher who established the evolution of Bacillus from its vegetative state to endospores with changes in the environment. Based on his life’s work, advances were made toward classifying microbes and understanding the complex nature of such microorganisms.


Microorganisms as a cause of disease

With all the advancements brought by the researchers mentioned earlier, it was not until 1876 that a clear relation between microbes and diseases was established. The person to do that was Robert Koch (1843-1910), and his first discovery was the cattle fell ill when Bacillus anthracis was transmitted from one cow to another.

His experiments involved taking blood from an infected animal and injecting it into a healthy specimen. The fact that the second cow became ill confirmed his theory that the Bacillus anthracis present in the blood was the cause of the disease. Furthermore, he grew the same Bacillus in broth and then proceeded to inject it into a healthy cow.

As expected, this experiment proved once more how the disease occurred. This causal link between microorganisms and diseases proved something that had eluded so many others before Koch.

The Golden Age of Microbiology

Koch’s discoveries started something that is historically known as the Golden Age of Microbiology. The agents of various epidemic diseases were discovered, and, based on these findings, the spreading of certain illnesses was stopped. There is no way of telling how the humankind would have evolved without the discoveries made by microbiologists.

Even if these advancements proved helped for prevention, little could be done to cure someone who was already infected. During the Second World War and after, further research was conducted, leading to the invention of antibiotics.

With the introduction of the new medicine, many diseases, such as tuberculosis, syphilis, and meningitis, became curable and their spread limited.

In 1940, the electron microscope was invented, and with its help, more microorganisms could be observed. The new device helped in the design of various vaccines during the 50s and 60s, that helped reduce and even eradicate severe illnesses such as polio.



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