Medical MicrobiologyThe 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 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?
What is Microbiology?
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
Microbes
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
Can microorganisms be good for us, beneficial? Explain your answer
What is Microbiology?
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 therefore
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 (1674) 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.
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
History of Microbiology: The Theories
Jar #1 Jar #2 Jar #3
• Left open • Maggots developed• Flies were observed
laying eggs on the meat in the open jar
• Covered with netting • Maggots appeared on
the netting• Flies were observed
laying eggs on the netting
• Sealed • No maggots
developed
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.
Spontaneous Generation
History of Microbiology: The Theories
The Question: What causes tiny living things to appear in decaying broth?
Lazzaro Spallanzani (1729-1799) In 1776 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.
Spontaneous GenerationThe Question: What causes tiny living things to appear in decaying broth?
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
History of Microbiology: The Theories
http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=27
Louis Pasteur’s Swan neck flask experiment
http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=27
History of Microbiology: The Theories French chemist Louis Pasteur’s design of
this experiment settled the argument.
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.
Louis Pasteur’s experiments
History of Microbiology: The Theories
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