1. Lecture 1A - History of Microbiology

2. History of Microbiology

3. What does life look like? First Recorded Observations of Microbes
Businessman
Used the previous work of Robert Hooke (English philosopher), who published in 1665 his observations with microscopes; coined the word “cell”
Leeuwenhoek refused to tell others how he made his lenses, so he had a monopoly
His lenses were of superior quality
Called the “father of microbiology”
Antony van Leeuwenhoek

4. Early Microscopy ~1670 Antony van Leeuwenhoek
made hand-held lenses ~300X magnification
first to observe live microbes – “animalcules”

5. What major contribution was made by Hooke?
What major contribution was made by van Leeuwenhoek?

6. The Golden Age of Microbiology
Scientists searched for answers to four questions
Is spontaneous generation of microbial life possible?
What causes fermentation?
What causes disease?
How can we prevent infection and disease? 6

7. Spontaneous Generation vs. Biogenesis
Spontaneous Generation – life arises from non-living things (soil, the environment, bad air)
Biogenesis – life arises only from living organisms, which may be too small to see

8. Spontaneous Generation vs. Biogenesis Francesco Redi - 1668
Question:
What causes maggots on rotting meat?
Observation:
Meat attracts flies
Hypothesis:
Meat forms maggots when flies are present
Method:
Meat placed in open and covered jars
First person to challenge theory of spontaneous generation by demonstrating that maggots comes from eggs laid by flies.

9. Spontaneous Generation vs. Biogenesis Francesco Redi - 1668
Results:
Only open jars produced maggots
Conclusion:
Results support hypothesis
Maggots form only when flies are present and allowed to leave their larvae on meat.
Rotting meat does not spontaneously produce maggots.

10. Spontaneous Generation vs. Biogenesis Louis Pasteur 1861
Hired by Napoleon III to determine the cause of souring in wine.
Found that many wineries in France were afflicted by some disease, souring or preventing flavor in wine
Found that sterile grape juice would not ferment into wine
Deduced that natural source of yeast was found on skin of grape
Was criticized, because this did not follow laws of spontaneous generation, which was held true by some
Pasteur crushed “spontaneous generation” using the swan necked flask experiments
“swan-necked” flasks

11. Spontaneous Generation vs. Biogenesis Louis Pasteur 1861
Question:
What causes growth of microbes in broth?
Observations:
Open broth containers 
Broth heated & covered 
Hypothesis:
Heating & and blocking airborne microorganisms from entering the flask (using a swan-necked flask) prevents microbial growth
Method:
Boiled broth in regular, open or swan-necked flasks
Flasks were observed for several days

12. Spontaneous Generation vs. Biogenesis Louis Pasteur 1861
Results:
Regular, open flasks –
Swan-necked flasks –
Conclusions:
Hypothesis supported
Heating in swan-necked flasks where airborne microbes cannot fall into the broth prevents growth of microbes
Microbes do not arise spontaneously in broth
Led to the idea and use of aseptic techniques

13. Fermentation and Pasteurization
Why did beer/wine sour?
Yeast converts sugar to alcohol without air.
With air, alcohol is converted to acetic acid by bacteria.
Acetobacter species convert ethanol to acetic acid in the presence of oxygen.
Spoil wine.
Used to make vinegar intentionally from wine.

15. Fermentation and Pasteurization
Pasteurization (1864) is the application of high heat for a short time
Gentle heat kills most bacteria
Gentle heat = 55 C
Developed rabies vaccine.
Figure 1.4

16. What were the major contributions of the following scientists?
Pasteur
Redi
Leeuwenhoek
Hooke
2. Explain pasteurization.
3. What is fermentation?
4. Explain the relevance Pasteur’s swan-necked flask experiments.

17. Joseph Lister Pioneer of surgical antisepsis.
Lister published in 1867:
Phenol applied to wound prevents infection
Surgeons should disinfect between patients with 5% phenol
Surgical instruments should be disinfected
5% phenol should be sprayed in operating room
Father of modern surgery

18. Germ Theory of Disease – Koch’s Postulates
Robert Koch – 1876
Proved bacteria cause disease
Studied anthrax
cattle disease
Developed “Germ Theory”
“Koch’s Postulates” – a sequence of experimental steps that verified the germ theory.
Developed pure culture methods

19. Koch’s Postulates
Observation
Cultivation

20. Koch’s Postulates
Introduction

21. Koch’s Postulates
Recovery

22. Koch’s Postulates Observation of disease signs & symptoms
Cultivation of organism in pure culture
Introduction of pure culture into healthy experimental animal
Recovery of same organism from experimental animals

23. Significance of Koch’s Postulates
scientific method to prove causation of disease
links specific organisms with specific diseases
gives a target for treatment of disease
Microbes cause disease!!!
can test treatments on cultured organism in the laboratory

24. What were the major contributions of the following scientists?
Pasteur
Redi
Koch
Leeuwenhoek
Lister
Hooke
Explain Koch’s postulates and why they are medically relevant.
Contrast spontaneous generation and biogenesis.