For billion of years the earth existed without any life form. It was only after several billion years more that the first bacteria appeared in the form of archaeans and cyanobacteria. In a later date, humans (Homo sapiens) came to existence when the earth had acquired a more conducive atmosphere. With this, bacteria developed new strains, multiplied and co-existed with man causing pathologic conditions, but man was still unaware of the underlying causes of these conditions.
One of the firsts recorded pestilence happened in Egypt in 3180. It was in 1900 that another plague, believed to be the bubonic plague caused the demise of the Greek army after the Trojan War. After these incidents, several more plagues/diseases were documented in other countries like China (smallpox) and Europe (syphilis).
It was only in the 16th century that a connection was made between existing pathologic conditions and microorganisms. The development of the microscope by Anton van Leeuwenhoek paved the way for the discovery of the first microorganisms: namely bacteria and protozoa. Because of his discovery, he was called the Father of Bacteriology. After his death, his letters to the Royal Society of London had made scientists aware of the genuine existence of microorganisms.
In 1858, Rudolf Virchow discovered the Theory of Biogenesis which states that any new life comes from a previously existing one. John Tyndall supported this theory with his own.
In the late 19th century, Louis Pasteur and Robert Koch eventually discovered very important contributions to microbiology. This field of science was named microbiology and dealt with minute, living organisms which could only be observed under the microscope.
Louis Pasteur in 1833 to 1895, made several significant discoveries which paved further the understanding of microbiology. The following are some of these discoveries:
He disproved the Theory of Spontaneous Generation (life comes from inanimate material) through his experiments.
He also discovered that not all microorganisms need oxygen to exist. This he called anaerobes.
He developed Pasteurization in which existing pathogenic microorganisms in wine were killed. This was done by heating wine at 55 degrees centigrade for at least 30 minutes.
In France, he found a method to prevent the spread of the silkworm disease that almost crippled the silk industry.
He also discovered that infectious conditions were caused by specific species of bacteria, e.g. Tuberculosis is caused by Mycobacterium tuberculosis.
He discovered how to prepare vaccines for chicken pox, anthrax, cholera, rabies and many others. These against animals at first, thereby helping solve the economic problem of France during those times.
These vaccines were further refined and used in humans.
Due to these discoveries, Louis Pasteur was a strong proponent of the observance of sterilized materials/environment in hospital settings, because he was aware that the spread of disease could be prevented through this process.
From 1843- 1910, Robert Koch, on the other hand made considerable success in the following areas:
He confirmed that Bacillus anthracis was definitely the causative agent of anthrax.
He discovered that Bacillus anthracis also had spores which were not easily destroyed. This made the organism resistant to some drugs.
He had found a way of observing microorganisms more clearly through staining methods.
He established culture methods in which bacteria were grown on solid media to facilitate their identification. Pure cultures were made from this.
Petri, his colleague invented the Petri dish in which culture media were placed.
Another colleague Frau Hess discovered the use of agar (from seaweed) as a solidifying agent in bacterial cultures.
He discovered two very significant microorganisms in the history of Microbiology: Mycobacterium tuberculosis the causative bacteria of tuberculosis and Vibrio cholera, the causative agent of cholera.
He also helped in the discovery of tuberculin test which is utilized in determining tuberculosis in a patient.
In 1884,he, together with colleagues, came up with the Koch's Postulates which are summarized below:
7.1. The microorganism in question must be found in all patients purported to have the disease and not in healthy beings.
7.2. The microorganism should be isolated from the infected being and can be cultured purely.
7.3. When the cultured microorganism is inoculated in a healthy animal, an identical disease should develop.
7.4. The microorganism obtained from the experimental animal should be the same as that previously inoculated.
If the microorganism has proven to be the same, then this would prove that the microbe in question is indeed the causative agent of the disease.
These postulates have been very significant in establishing further methods for the discovery of more laboratory methods to aid in the identification of microbes.
Viruses, Chlamydia and Rikettsia do not follow Koch's Postulates as they could only be cultured in living host cells.
Up to this day, Koch's postulate is still being observed by scientists all over the world.
In 1870s to 1880s, the term bacillus was used. An antitoxin to Diphtheria was discovered by Ferdinand J. Cohn and Shibasuburo Kitasato respectively.
During the 1990s and onwards, transduction and genetic make-up of viruses came into focus with Lederberg, Zinder and a lot of scientists. Temin and Baltimore also discovered an enzyme in viruses called transcriptase which had great effect in the RNA and DNA flow.
In 1995, genomes were the area of concentration when Claire Fraser and colleagues had the first completed genome sequence of Hemophilus influenza.
Year 2000 and onwards, Polymerase Chain Reactions (PCR), gene replication, genome elucidation, and genetic engineering are being experimented on. These are very delicate and intricate procedures which can have a massive impact on Microbiology.
The history of Microbiology does not end in our times. It is a dynamic science and will continue to grow and be updated until our era will become a history for the future generation. Hopefully, we would have contributed positively to the advancement of this very interesting field of science.
Burton, Gwendolyn et al, Microbiology for the Health Sciences, Lippincott Williams and Wilkins, 1998