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International Journal of Infectious DiseasesVolume 14, Issue 9, September 2010, Pages e744-e751 Author links open overlay panel https://doi.org/10.1016/j.ijid.2009.12.003Get rights and content Under an Elsevier user license Open archive SummaryRobert Koch's discovery of the anthrax bacillus in 1876 launched the field of medical bacteriology. A ‘golden age’ of scientific discovery ensued. A century after Koch's death, we remember his life and work. KeywordsRobert Koch Anthrax Tuberculosis Cholera Bacteriology Medical history Cited by (0)Copyright © 2010 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved. Theory of Spontaneous GenerationThe PneumaBefore Cell Theory There Was.... The Theory of Spontaneous Generation Before Cell Theory...The Theory of Spontaneous
Generation
Not only was this idea somewhat universal, but it took centuries to convince even some of the most creative scientific minds of the fallacy (untrue nature) of the theory of Spontaneous Generation. The "Observations" that lead to the Theory of Spontaneous Generation
Equivocal Generation
First Evidence Against Spontaneous Generation - 1668 by Francesco RediItalian physician Francesco Redi performed an experiment in 1668 that proved that maggots DO NOT spontaneously generate on rotting meat.
Francesco Redi (1626 - 1697)Francesco Redi's 1668 Experiment
Conclusions of Redi's Experiment
John Needham (1713–1781) Redi's conclusions were met with disbelief by many scholars and scientists. In 1745, John Needham sought to disprove Redi's findings and performed the following experiment. Needham briefly boiled broth containing plant and animal matter, in an effort to kill any existing microorganisms. The broth was then kept sealed and left to incubate for three days. After three days, the broth was visibly cloudy and microbes were observed in the broth using a microscope. Needham concluded that these microscopic organisms had spontaneously generated from the broth. His conclusion supported the Theory of Spontaneous Generation and refuted Redi's claims. Later, it was found that John Needham's experiment was flawed, because he had not allowed the broth to boil long enough to kill all of the pre-existing microbes. Lazzaro
Spallanzani (1729–1799) John Needham held fast to his belief in spontaneous generation, despite Spallanzani's experimental evidence. Needham explained away Spallanzani's experimental results by postulating that the "life force" needed for spontaneous generation was destroyed when the broth was boiled, and that sealing the boiled broth prevented any new "life force" from forming. Spallanzani hypothesized that spontaneous generation could not occur in the broth without the broth having an intact "life force". The legitimacy of the theory of spontaneous generation continued to be the source of heated debate until the mid 1800's. THE DISCOVERY OF CELLS AND CELL THEORY Life comes in a huge variety of shapes, sizes, composition and physiology. Some of the largest organisms to ever roam the Earth, like the blue whale, exceed 150 tons, whereas the smallest organisms are only visible using microscopes. Our current understanding of "life" is centered on The Cell Theory which was developed over hundreds of years, due to the contributions of countless scientists and numerous inventions, experiments and observations. These discoveries were made possible due to the invention of high-powered microscopes in the 17th century. The Invention of the MicroscopeThe discovery of cells and the development of cell theory due to the invention of high-powered microscopes in the 17th century.Antique Microscope - Jansen's microscope consisted of three draw tubes with lenses inserted into the ends of the flanking tubes. The first microscopes were simple and very limited in magnifying power. There is some debate surrounding who invented the first microscope, but there is evidence of early microscopes as early as the first century. Zacharias Jansen and the first compound microscope The first compound microscope was not invented until the 1590's. Zacharias and Hans Jansen were able to combine magnifying lenses together that resulted in an image that was 9 times larger than what could be seen with the naked eye.The Discovery of Cells by Robert Hooke (1660)
Robert Hooke was the first person to view tissues under a microscopic. He identified the distinct structures that made up the tissue as "cells".
Anton van Leeuwenhoek“The Father of Microbiology"
Cells had already been discovered by Hooke, but these were plant cells. Animal cells and bacteria cells were discovered by Anton. Before this time, microorganisms were hypothesized, but never observed. Many people were resistant to the idea that something could exist that was too small to be seen with the naked eye.
The Cell Theory began with Robert Hooke's discovery and observation of cells. As awesome as this discovery was, the true significance of this discovery was not fully realized until centuries later! It was only then that the structures Hooke coined as "cells" would be found to be the fundamental unit of life! Louis Pasteur Louis Pasteur was a pioneer in microbial fermentation and he invented the process of pasteurization which bears his name.
In 1858, Pasteur successfully transferred microbes that had attached themselves onto a piece of gun-cotton from the air, to broth. He was able to perform this transfer without exposing the broth to the air. After several days of incubation, the broth contained many microorganisms. Pasteur concluded that microorganisms were coming from the air directly. This experiment showed evidence against the idea that the microorganisms appear in broth due exposure to the air which gave the broth a "life force". Louis Pasteur performed a series of experiments that presented overwhelming evidence against the theory of spontaneous generation. Many consider these experiments to be the "death blow" to the Theory of Spontaneous Generation. Swan-Necked Flasks
Watch my 6 minute video onPasteur's Swan-Necked Flask Experiments
Cells are the fundamental unit of life!Matthias Schleiden (1804–1881)
Vaccines The first vaccine was developed in 1796 by Edward Jenner against Smallpox. Edward Jenner observed that milkmaids who had
previously been infected with a similar disease called cowpox, were protected from smallpox. The principle behind vaccinations is that a disease can be prevented by exposing the subject to a milder form of the disease-causing agent. Interestingly, the term "vaccine" came from the term "Variolae vaccinae" which means "smallpox of the cow". Disease TransmissionIn the 1700s and earlier, it was thought that diseases were spread through by MIASMA. Miasma were thought of as foul smelling rotting particles in the air that could cause disease. As more scientific information became available, new outbreaks of disease led to new scientific inquiries which gave to the field of epidemiology. John Snow (1813 – 1858)
The Red Granite kerbstone mark is the site of the historic Broad Street pump associated with Dr John Snow's discovery in 1854 that cholera is conveyed by water. “Golden Age of Microbiology”1857 through 1914Ignaz Philipp Semmelweis (1818 – 1865)
Semmelweis was coined "the Savior of Mothers". Puerperal fever was common in the 1850's and was often fatal. Aseptic techniques he created involved disinfecting the hands with a chlorinated lime solution. He published a book of his findings in Etiology, Concept and Prophylaxis of Childbed Fever. Puerperal fever monthly mortality rates at Vienna Maternity Institution 1841–1849. Rates drop when implementing hand washing. Sammelweis's ideas were met with disbelief by many members of the scientific and medical communities. Non-sterile environments were still commonplace, resulting in extraordinarily high (~ 50%)
mortality rates among patients who had undergone various surgical procedures. Sammelweis demonstrated that the non-sterile environments that the patients endured during surgeries, lead to the development of these deadly post-operative infections. Louis Pasteur (1822–1895)Louis Pasteur was one of the proponents of The Germ Theory, that states that germs are the cause of infectious disease, and is often miscredited as its creator. Pasteurization and Fermentation 1864Semmelweis's ideas were finally popularized after his death, due (in part) to a series of experiments performed by Louis Pasteur confirmed the germ theory and Joseph Lister, who practiced and operated, using hygienic methods, with great success.
Joseph Lister (1827 - 1912)Joseph Lister in 1902 John Lister also furthered the earlier work by Ignaz Semmelweis (1818–1865) who had developed
the practice of sterile techniques and demonstrated the link between the non-sterile environment and disease. In 1865, Joseph Lister developed the practice of antisepsis, which is the chemical disinfection of external living surfaces.
Robert Koch 1876Statue of Koch in Berlin Koch's Postulates
Timeline of Germ Theory
https://upload.wikimedia.org/wikipedia/commons/thumb/8/8f/OSC_Microbio_03_02_GermTimeln.jpg/305px-OSC_Microbio_03_02_GermTimeln.jpg The History of Virology Virology is the scientific study of viruses and viral infections. Virology is a new science that began in the late 19th century with studies performed by Dmitry Ivanovsky and Martinus Beijerinck. Illustration of a Pasteur-Chamberland filter The hunt was on to find the disease-causing agents of different illnesses in order to make new vaccines and to further scientific knowledge. The isolation of bacteria involved a process called filtering. Viruses are about ten times smaller than bacteria cells. So scientists knew that the disease causing agent was smaller than the bacteria cells that were being collected using the filters of the day. The challenge was to make a filter that had pores tiny enough to trap these extraordinarily tiny disease-causing organisms, later to be identified as viruses. Pasteur and Chamberland created a new filter, called the Pasteur-Chamberland filter, which was able to trap viruses. The invention of the Pasteur-Chamberland filter lead to the first classification of viruses. These classifications were 1) “filterable viruses” (able to pass through filter) and 2) "non-filterable viruses".
Soon after, new specialized fields of study began including mycology (the study of fungi), protozoology (the study of parasitic protozoans) and microbial ecology (the study of the ecological role of microorganisms). The Second "Golden Age" of MicrobiologyMICROORGANISMS AS RESEARCH MODELS
In 1944, Oswald Avery, Colin MacLeod, and Maclyn McCarty, were the first to identify deoxyribonucleic acid (DNA) as the genetic material found in cells. This important discovery was made using the bacterium, Streptococcus pneumoniae. This discovery was later confirmed in 1953 by experiments performed by Alfred Hershey and Martha Chase, in which a virus was used to infect bacterial cells. THE ELECTRON MICROSCOPE
The first electron microscopes were developed in the 1940s. Electron microscopes form an image of the specimen using a beam of electrons instead of light. Since electrons have a wavelength of only about 1 nm, the electron microscope can magnify a specimen up to about 100,000X. For comparison, a good compound microscope might be able to magnify a specimen up to about 2,000X. PROKARYOTIC CELLS AND EUKARYOTIC CELLS
With this new technology, scientists were able to peer inside the cell like never before. The structure and organization of cells was realized and refined. Before electron microscopes, only the structure of plant and animal cells were known, due to their size. After being able to reexamine many of the known microorganisms using electron microscopy, variations become evident. Protista and fungi were found to have the same basic cellular structure as plants and animals. Protista and fungi also had DNA that was house in a nucleus surrounded by a nuclear envelope and membrane-bound organelles. For this reason, the protista, fungi, plantae and animalia were categorized as the 4 kingdoms of the eukarya or eukaryota domain. THE "MAGIC BULLET"THE DISCOVERY OF PENICILLIN
Soon after, the antibiotics actinomycin and streptomycin were discovered in samples of soil and were instrumental in treating tuberculosis. These discoveries were followed by many many more and numerous diseases were treated. However, overuse of antibiotics has lead to antibiotic-resistant strains of bacteria which is a problem we are still facing today. The Third Golden Age of Microbiology The third golden age of microbiology can be summed up in one word... BIOTECHNOLOGY. Advances in the fields of microbiology, nanotechnology, and bioengineering have revolutionized the medical field. Microorganisms can be directed in the body to serve specific functions for the benefit of the patient. Genetically engineered microbes can be sent through the body as protein factories. What happened to second golden age of microbiology?The second Golden Age
The unity that Pasteur originally brought to the discipline by applying similar approaches to medical and environmental microbiology was replaced by spe- cialized subdisciplines.
What occurred during the golden age of microbiology?Between Pasteur and Koch, the Golden Age of Microbiology achieved its greatest discoveries. Pathogens were identified, vaccines created, methodologies perfected, and foundations established that support modern research today.
What are 2 historical advances in microbiology?Pasteurization, penicillin, Koch's postulates, and gene coding. These discoveries and inventions are vital yet commonplace in modern life, but were radical when first introduced to the public and academia.
What was the main landmark discovery that happened during the golden age of microbiology?The proof of microorganisms as the real etiological agents of infectious diseases marks the zenith of the period between 1850 and 1915 known as the Golden Age of Microbiology. This landmark coincided with the promulgation and promotion of the Nobel Prize in 1901.
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