A SELECTIVE HISTORY OF MICROBIOLOGY

1.) Contagion

This is an old idea - there is something out there which causes disease and you can catch it.
Terms like malaria and miasma referred to poisonous vapors which when breathed in could cause disease.
Along this line there was also the idea that the breathing in of certain vapors and smells could protect from disease. - conflicting strategies: like protects from like ie. Breathe in bad smells to protect or others would recommend that opposites will protect ie. Perfumes will protect. (see how a mysterious disease laid low europes masses (mr)).
The idea of immunity is also an ancient one.
The Chinese practiced variolation centuries ago.
Thucydides described an epidemic in Athens (430 BCE) and noted that the survivors were immune to reinfection.
Girolamo Fracastoro (1546) is credited with the first written allusions to the germ theory of disease. he wrote about seminaria morbis - seeds of disease which can pass from one individual to another. Fracastoro also named syphilis.

2.) Spontaneous generation and biogenesis

Many ancient accounts about where living organisms come from.
An old recipe for bees called for killing and burying a young bull so that its horns protude from the soil. After one month bees should appear.
An alternative bee generator was honey.
Aristotle claimed that moist soil was the generator of snakes, toads and mice.
Maggots were supposed to be generated by decaying meat.
Discuss experience with tumbu fly.
1600s - Redi's experiment with meat in a jar with a gauze proved that you needed flies to get maggots, settling at least part of the spontaneous generation debate.
Also in the 1600s - Hooke and Leeuwenhoek describe cells and animalicules and the debate centers around the generation of microbes.
1700s - Spallanzani did experiments with broth and showed that when sealed and boiled no microbial growth occured. However flasks which were boiled but left open,became cloudy with growth.
These experiments were criticized because of the lack of vital force in the sealed flasks.
1800s - Louis Pasteur and his gooseneck flasks -- (see figure in Tortora et.al.)
1.) Allowed free entry of air (therefore vital force was present
2.) Gooseneck baffle prevented the entry of particles
3.) If broke the neck then the broth got cloudy
4.) Therefore no spontaneous generation -- the microbes were found in the air. Also showed that microbes could be destroyed by heat. This was the beginning of aseptic technique.


So is spontaneous generation false?

According to current theory -- life on this planet is believed to be approx. 3 -3.5 billion years old and this life arose slowly and spontaneously out of a primeval soup.
The early atmosphere is believed to have contained significant quantities of:

NH3 (AMMONIA)

CH4 (METHANE)

H2 (HYDROGEN)

CO2 (CARBON DIOXIDE)

H2O (WATER)

 

No O2 (Oxygen) Though - Free O2 Is Believed To Have Been Formed By Life

There was also plenty of energy:

Sunlight (radiation)

Lightning

Geothermal

There most probably were visitors from outer space, such as: meteorites, comets and space dust
Miller and Urey at the University of Chicago used spark chambers to reproduce these conditions and were able to form a variety of organic substances found associated with life: amino acids, carboxylic acids, urea, formaldehyde, cyanide, etc. Precursors of proteins, nucleic acids, lipids and carbohydrates. (see Lewis, pgs. 53-56).
It is important to note that the unity of biochemistry also infers a common ancestry of life:
Nucleic acids -- universal genetic information, code the synthesis of proteins (enzymes)
Amino acids (20 of them) -- universal subunits of proteins.
Nearly universal metabolic pathways ie. Glycolysis (glucose metabolism).
Two main mechanisms of energy acquisition by living organisms:
phototrophs - get energy from light (sun)
chemotrophs - get energy from molecules
Two main mechanisms for carbon acquisition by living organisms:
autotrophs - get carbon from CO2
heterotrophs - get carbon from organic molecules
Some people say that the chemoautotrophic Archaea were the first.

 

3.) Louis Pasteur's other contributions:

He turned his attention to a variety of diseases:
it is important to remember that Pasteur did not work in a vacuum:
Pasteur was the first to describe and explain the process of fermentation: -- the transformation of a food through the growth and metabolism of a microorganism. This work was done on beer and wine.
He described that these foods were made by the metabolic action of yeast on wort (for beer) and grape juice (for wine).
He described bad ferments and good ferments as well as the organisms seen in both.
He developed the process now known as pasteurization as a way to insure consistent good fermentations.

Pasteur developed methods for

Growing the organism which causes chicken cholera. He discovered a way to attenuate the organism and produce a vaccine against the disease. This was the first rationally developed, manufactured vaccine.
Pasteur worked with rabies -- a virus -- a type of organism which had not yet been discovered. He learned how to culture it by passing it through rabbits. He learned how to attenuate the virus by ageing and drying the brains of infected rabbits. The attenuated material became the basis for the first rabies vaccine which was tried on a nine year old boy, Joseph Meister, who had been badly bitten by a rabid dog.

4.) Robert Koch
 
Koch, a contempory of Pasteur, also contributed greatly to the development of microbiology:
He isolated and cultured a number bacterial agents of disease such as:

 

Koch's work on pure cultures of bacteria was made possible by the development of solid media by his laboratory. The idea of incorporating agar into media is attributed to Fannie Eilshemius Hesse the American wife of one of Koch's assistants.
She used this polysaccharide derived from marine algae (seaweed) to help solidify her jams and jellies. In Hawai‘i we call agar, kanten.
Koch's postulates are a series of rules or steps that must be followed in order to identify and confirm the disease-causing relationship between a microbe and a specific disease. These are the steps you use to prove that a particular organism causes a specific disease.:
        1. One must isolate the organism in pure culture from all cases of the disease.
        2. One must observe the same disease when the cultured organism is inoculated into a healthy host experimental animal.
        3. One must be able to isolate the same organism in pure culture from the disease experimental animal.
 
(What happens if there is no good animal model for a disease? Peter Duesberg and his views on AIDS.)

5.) Immunology

Koch's work as well as Pasteur's confirmed and established the germ theory of infectious disease. The stage was now set for the development of immunology:
Antigen- any substance which cause an animal to make antibody typically this would be
    • Dead or live bacteria
    • Parts of bacteria
    • Viruses
    • Plant molecules
    • Animal molecules
    • Toxins and toxoids
Antibody - protein made by animals in response to an antigen. This protein will react with the antigen. Antibodies have several names:
Serum therapy was developed

6). Virology

1898 - 1900 viruses discovered:
    • tobacco mosaic virus
    • foot and mouth disease
    • yellow fever

7.) Discovery of Antibiotics

    • 1930s - sulfa drugs - from chemical industry in Germany
    • Penicillin - Fleming and Florey in Great Britain

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