Ch'1 Historical Developments

1
Ch.1 Historical Developments

• Discovery of microorganisms
• Golden Age of Microbiology
• Disciplines of microbiology

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Discovery of microorganisms

• What is microbiology?
• Study of small organisms generally too small to
  be seen with the naked eye
• Biomass of Earth
• 50 microorganisms
• 35 plants
• 15 animals
• 1674 van Leeuwenhoek discovered animalcules
• Father of microbiology
• Interest in microbes came about because of 2 Qs
• Where do living things come from?
• What causes disease?

3
Where do microbes come from?

• Spontaneous generation Theory
• 346 B.C. Aristotle Life appears from nonliving,
  often decaying matter spontaneously
• All organisms arise from other organisms like
  themselves (Pasteur)
• Experiments occur both on a macroscopic level and
  a microscopic level

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Macroscopic studies of spontaneous generation

• Proponents
• Aristotle worms appear on decayed meat
• Van Helmont mice arise in a jar containing corn
  that was stored in the dark

• Opponents
• Redi Experiments with rotting meat and flies
• Meat containers with lids
• Meat containers with nets
• Meat containers without lid or net
• Results ???

5
Microscopic studies of spontaneous generation

• Proponents
• Needham Experiment
• Heat meat broth
• Stopper the flask
• Observe for growth
• Results
• microbes arose even in boiled broth

• Opponents
• Spallanzani
• Boiled broth in hermatically sealed flasks and no
  growth
• Schwann
• Sterilize air by heating it
• Schroeder Dusch
• Air enters through sterile cotton is not heated
• Pasteur

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Pasteurs experiment for disproving spontaneous
generation
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Outcomes of the great debate

• Microbes give rise to other like microbes
• Methods to study microbes must prevent
  contamination ( entry of any organism)
• Sterile materials required to prevent
  contamination
• Sterilization killing of all organisms
• Pasteurization reduction of numbers of organisms
  in fluids by heat

8
Contamination of media

• Tyndall (1877)
• Microbes were carried on dust particles in air
• Microbes exist in two forms
• Heat sensitive
• Heat stable requires repeated heating and
  cooling to kill, called Tyndallization
• Cohn (1877)
• Bacteria produced spores which where responsible
  for heat stable forms
• Spores resistant and dormant forms of some
  microbes (Bacillus anthracis)

9
Golden Age of Microbiology

• Kochs postulates
• Listers sterilization experiments
• Jenners vaccination experiments
• Pasteurs rabies vaccine

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Kochs postulates

• Isolation same organism can be found in all and
  only sick animals
• Cultivation organisms can be obtained and grown
  in pure cultures
• Transference inoculation of cultured cells into
  healthy animals transfers disease
• Reisolation same organism can be reisolated
  from the infected animal and cultured again

11
Kochs Materials

• Growth of microbes on solid nutrient media
• Potato slices were clumpsy
• Nutrient media in gelatin caused problems
• Melted during inoculations with heat
• Some organisms digested it
• Nutrient media in agar solves problems
• Polysaccharide from seaweed (Frau Hesse)
• Dissolves and melts at 100ºC, solidifies at
  45ºC
• Petri dishes (Richard Petri)

12
Organisms isolated using Kochs Postulates

• 1876 Koch Bacillus anthracis ?
• 1879 Neisser Neisseria gonorrhoeae ?
• 1882 Koch Mycobacterium tuberculosis - ?
• 1894 Yersin Yersinia pestis - ?

13
Listers sterilization experiments

• Surgical procedures often resulted in death of
  the patient from bacterial infections
• Defend against disease by eliminating germs
• Lister used chemicals to sterilize operating
  rooms and surgical tools
• Room and instruments sprayed with a phenol
  (carbolic acid) solution
• Figure 1-10

14
Jenners vaccination experiments

• Animals have natural defense mechanisms against
  disease
• Immunity resistance to disease
• Phagocytes, antibodies
• Immunology study of mechanisms of immunity
• Started with Jenner who developed the 1st
  vaccination for smallpox

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Smallpox Immunization

• Smallpox was caused by a that cannot be grown in
  culture on any laboratory media
• Two forms of the disease
• Variola major (30 fatalities)
• Variola minor (1 fatalities)
• Survivor of either disease became immune to both
• Variolation deliberate infection w/ mild form
  (Variola minor)
• Jenner noticed that milkmaids were also immune to
  smallpox but had attracted cowpox
• Vaccination Infection with cowpox

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Pasteurs rabies vaccine

• No mild form of rabies all fatal
• Reservoir generally dogs and cats
• Attenuation method to reduce virulence of
  pathogen and then the less virulent form is used
  as vaccination
• injected rabbits with rabies virus
• took spinal fluid of infected rabbits for
  reinfection of other rabbits and then finally as
  a vaccine
• now use recombinant DNA to do this

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Disciplines of microbiology

• Chemotherapy (Erhlich)
• Chemicals which act as magic bullets to cure
  disease
• Used arsenic to cure syphilis
• Sulfa drugs in 1930
• Penicillin developed during WWII
• Molecular Biology
• Gene therapy, recombinant DNA technology
• Microbial genetics, microbial ecology,
  pathogentic microbiology, immunology