Transcript Spontaneous Generation

Medical Microbiology
The History
EQ: Who are the major contributors to the
development of Microbiology?
What is Microbiology?
 They study of microbes or microorganisms
 Microbes, or microorganisms are minute living things that are
usually unable to be viewed with the naked eye.
What is Microbiology?
What are some of examples of
microbes?
 Bacteria, fungi, protozoa, algae, viruses, and some are
parasites (helminths)
 Some are pathogenic
What is Microbiology?
Microbres
 When you hear the word bacteria, what comes to your mind?
 Not all bacteria cause disease
 Most bacterial species cannot cause disease
Figure 1. Gram stain of a species of Micrococcus, commonly
isolated from the skin and nasal membranes of humans. Figures
from: http://textbookofbacteriology.net/normalflora.html
What is Microbiology?
Microbes
 Can microorganisms be good for us, beneficial? Explain your
answer
 Many species play beneficial roles
 Production of antibiotics and foodstuffs
 Decompose organic waste
 Produce industrial chemicals such as ethyl alcohol and acetone
 Produce fermented foods such as vinegar, cheese, and bread
Ancient Microbiological
History
 Ancient people recognized many
factors involved in diseases.
 Most ancient people documented
that some diseases are
communicable
 Example: When Black Death struck
Europe entire villages were
abandoned in an effort to escape
the highly infectious plague (1347
A.D)
 No medical knowledge existed in
Medieval England to cope with the
disease.
Ancient Microbiological History
 The Romans were a hygienic bunch and were concerned with
health and cleanliness (waste and sewage).
 The Romans invented the first underground sewage system
Ancient Microbiological History
 The Romans understood that sewage could cause disease and
there for decided to build an underground sewage system which
is an idea we still use today.
 A network of pipes brought clean water into the city of Rome and removed
waste.
 Waste flushed from the latrines flowed through a central channel into the
main sewage system and thence into a nearby river or stream.
 The public bath houses was the place where people went to
socialize and do business as well as getting clean.
History of Microbiology?
 Discovering organisms
 First microbes were observed in 1673
 Robert Hooke- In 1665 reported that living things were composed of
little boxes or cells
 devised the compound microscope and illumination system
 Antoni van Leeuwenhoek- (1673-1723)
 He is considered the father of bacteriology
 Made simple microscopes and began observing with them
 Discovered bacteria (he called them animalcules)
 Leeuwenhoek's microscope consisted simply of:
 A) a screw for adjusting the height of the object being
examined
 B) a metal plate serving as the body
 C) a skewer to impale the object and rotate it
 D) the lens itself, which was spherical
History of Microbiology: The
Theories
 Spontaneous Generation
 Many believed in spontaneous generation:
 Aristotle synthesized the hypothesis which stated that some vital
force contained in given organic matter can create living
organisms from inanimate objects.
 In basic terms spontaneous generation stated that living
organisms arise from non living matter.
History of Microbiology: The Theories
Spontaneous Generation
 Spontaneous generation was disproved in 1668 by Italian
Scientist, Francesco Redi.
 What are the steps to the scientific method?
 If your were Francesco Redi, what experimental design would
you create to disprove spontaneous generation?
Redi’s Experiment:
 Redi’s question: Where do maggots come from?
 Hypothesized: Redi suspected that flies landing on the meat laid
eggs that eventually grew into maggots
 Experiment: Placed meat in three separate jars
History of Microbiology: The Theories
Disproving Spontaneous Generation:
Redi’s Experiment
Jar #1
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•
•
Left open
Maggots developed
Flies were observed
laying eggs on the
meat in the open jar
Jar #2
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•
•
Covered with netting
Maggots appeared on
the netting
Flies were observed
laying eggs on the
netting
Jar #3
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Sealed
No maggots
developed
History of Microbiology: The Theories
Spontaneous Generation
 The Question: What causes tiny living things to appear in decaying
broth?
 John Needham- revived the theory of spontaneous
generation in 1745
 Needham theorized that if he took chicken broth and heated
it, all living things in it would die.
 After heating some broth, he let a flask cool and sit at a
constant temperature. The development of a thick turbid
solution of microorganisms in the flask was strong proof to
Needham of the existence of spontaneous generation.
History of Microbiology: The Theories
Spontaneous Generation
The Question: What causes tiny living things to appear in
decaying broth?
 Lazzaro Spallanzani (1729-1799)
 He demonstrated that microorganisms were already in the
solution, the container, or the air
 He took solutions which he knew would "breed" organisms and
boiled them for up to an hour. The flasks were hermetically
sealed to keep out contaminated air.
History of Microbiology: The Theories
Biogenesis
 In 1858 German scientist, Rudolf Virchow challenged
spontaneous generation with his concept of biogenesis
 Living organisms arise from pre-existing life
 Virchow presented his idea to the scientific community, but could
not back it up with a convincing experiment
History of Microbiology: The Theories
Settlement of Spontaneous Generation
 In 1861, a French scientist by the name of Louis Pasteur
demonstrated where microorganisms came from
 Father of Medical Microbiology
 Demonstrated the microorganisms exist in the air and could
contaminate sterile solutions by passing air through cotton filters
 The filter trapped tiny particles floating in the air
http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=27
History of Microbiology: The Theories
Louis Pasteur’s Swan neck flask
experiment
http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=27
French
chemist
Louis
Pasteur’s
design of
this experiment settled
the argument. Click here
for an animation and
quiz.
History of Microbiology: The Theories
Louis Pasteur’s experiments
 Louis Pasteur performed numerous experiments to
discover why wine and dairy products became sour
 He found that bacteria were to blame (lactic acid fermentation)
 Pasteur called attention to the importance of microorganisms
in everyday life and stirred scientists to think that if bacteria
could make the wine “sick,” then perhaps they could cause
human illness.
Golden Age of Microbiology
1857- 1914
 Beginning with Pasteur’s work, discoveries included the
relationship between microbes and disease, immunity and
antimicrobial medicine
 Germ Theory of Disease
 Germ theory states that specific microscopic organisms are the cause of
specific diseases.