History of Microbiology - PowerPoint PPT Presentation

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History of Microbiology

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History of Microbiology Nature of Science Early Observations Spontaneous Generation Controversy Germ Theory of Disease Nature of Science Science is systematized ... – PowerPoint PPT presentation

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Title: History of Microbiology


1
History of Microbiology
  • Nature of Science
  • Early Observations
  • Spontaneous Generation Controversy
  • Germ Theory of Disease

2
Nature of Science
  • Science is systematized knowledge developed
    through the application of the scientific method
  • Scientific method
  • Observations (objective vs. subjective)
  • Formulate hypothesis
  • Test hypothesis with controlled experiments
  • Accept, revise or reject hypothesis

3
Early Observations Experiments
  • Microscopes
  • van Leeuwenhoek Hooke
  • Spontaneous Generation Controversy
  • Germ Theory of Disease Robert Koch

4
Spontaneous Generation
  • Biogenesis vs. Abiogenesis
  • Aristotle
  • Jan Baptista van Helmont (1580-1644)
  • Francisco Redi (1626-1697)
  • John T. Needham (1713-1781)
  • Lazzaro Spallanzani (1729-1799)
  • Theodor Schwann (1810-1882)
  • Louis Pasteur (1822-1895)

5
Biogenesis vs. Abiogenesis
  • Biogenesis - development of life from preceding
    life forms
  • Abiogenesis - life arises from inorganic or
    non-living materials

6
Aristotle
  • first to record possible routes to life.
  • He saw beings as arising in one of three ways,
    from sexual reproduction, asexual reproduction or
    nonliving matter.
  • observable that aphids arise from the dew on
    plants, fleas from putrid matter, and mice from
    dirty hay
  • this belief remained unchallenged for more than
    two thousand years.

7
Jan Baptista van Helmont (1580-1644)
  • Reported in late 1500s that barley grains and
    old shirts left in a corner would spontaneously
    give rise to mice
  • Claimed as evidence that supported spontaneous
    generation or abiogenesis

8
(No Transcript)
9
Francisco Redi (1626-1697)
  • Set up controlled experiment to test idea of
    spontaneous generation with respect to maggots
    appearing on rotting meat
  • open jar with meat
  • screened jar with meat
  • sealed jar with meat

10
von Helmut
open
screened
sealed
11
John T. Needham (1713-1781)
  • Flies do not arise spontaneously but the
    animalcules described by van Leeuwenhoek must
  • In 1748 Needham boiled mutton broth, stoppered
    and noted that flask becam turbid
  • Argued that the turbidity, which included many
    animalcules must have arisen spontaneously

12
Lazzaro Spallanzani (1729-1799)
  • Repeated Needhams experiments
  • Used flasks that were sealed by melting the glass
    rather than with a cork
  • Found that if sealed properly, flasks boiled 45
    minutes would remain sterile thus refuting
    Needhams conclusions

13
Theodor Schwann (1810-1882)
  • An argument against Spallanzani experiments is
    that they excluded air
  • Constructed apparatus to sterilize air coming
    into flask
  • Results supported biogenesis

14
Theodor Schwann (1810-1882)
  • Apparatus used by Schwann The central flask,
    which is being rendered sterile by heating
    contains the infusion. Air is passed through it
    from the heated coil on right. The flask at left
    is a mercury trap through which air escapes after
    passing through the central flask.

15
Louis Pasteur (1822-1895)
  • Looked at air which had been filtered
  • Developed swan neck flask to deal with heated air
    problem
  • Looked at frequency of occurrence of contaminated
    flasks
  • Settled controversy

16
Louis Pasteur (1822-1895)
  • An example of the swan-necked flask

17
Germ Theory of Disease
  • Observation on causative agents of potato blight
    and diseases of silkworms led to hypothesis
  • Formalized through work of Pasteur and Koch (and
    others) led to theory that germs or
    microorganisms may cause disease

18
Germ Theory of Disease
  • Robert Koch first developed relationship between
    microorganisms and disease
  • Developed Kochs Postulates for testing
    relationship
  • Discovered cause of anthrax and tuberculosis

19
Germ Theory of Disease
  • Kochs Postulates
  • Same microorganism must be observed in every
    instance of disease
  • Organism must be isolated from diseased host and
    grown in pure culture
  • Specific disease must be reproduced when pure
    culture is reintroduced into host
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