1. History of Microbiology
Lecture #2
Bio3124
University of Ottawa

2. Old times…
Humans knew how to deal with germs before even knowing about their existence
Storing food in cooler temperatures
Salting, drying, smoking
Use of spices
Cremation of dead
concealing and burying dead beyond a nearest passing river or in a distant area
Explanation: traditional, mystical and superstitious

3. Discovery of Microorganisms
Antony van Leeuwenhoek ( ), the father of microbiology
a hobbyist microscopist Dutchman
first to observe and describe microorganisms accurately

4. Leeuwenhoek’s microscope
Composed of one lens
Light shines objects at a 45˚ angle
Worked like a dark field microscope
Magnification: fold
bright microorganisms could be seen in a dark bkg

5. Leeuwenhoek’s Observations
Spirillum as seen by Leeuwenhoek’s microscope
Tripartite structure of a human sperm
PMN
RBC
Original blood smear image by Leeuwenhoek
Note the polymorphonuclear cell and RBC
Reported to the Royal Society of London (1673)
Accurate shape, detailed movement
Subjects were most possibly bacteria and protozoa and called them “animalcules“
also reported spermatozoa, blood cells

6. Don’t forget to check out the paper by Brian J
Don’t forget to check out the paper by Brian J. Ford about Leeuwenhoek posted under literature button in your website

7. 17th century Robert Hooke and Antony Van Leeuwenhoek
Using the microscope to observe the fruit organs of mushrooms and mouth bacteria.

8. Where do microorganism originate from?
Few days of being
exposed to air.
Spontaneous generation??

9. The Conflict over Spontaneous Generation
living organisms can develop from nonliving or decomposing matter
publicly a common sense vision with societal and cultural roots (almost years ago)
Examples:
flies from rotten meat and animal carcasses
Mice from fungus infested grain barns
Scientific methodology was not established
What was the proof?

10. Jan Baptista Van Helmont (1577-1644)
A Flemish noble man, alchemist and physician
discovered carbon dioxide, introduced the term gas in its present scientific sense
believed in spontaneous generation

11. Don’t forget to check out the paper by Louis Rosenfeld about Van Helmont posted under literature button in your website

12. Jan Baptista Van Helmont The Origin of life (17th Centuray)
Adult mice

13. Spontaneous Generation

14. But could spontaneous generation be true for microorganisms?

15. Francesco Redi (1626-1697) First blow to spontaneous generation
Laying eggs is required for maggots and flies to come to existence
Supporters of SG: Life is necessary in order to bring about life in certain cases!

16. John Needham ( )
Conclusion: Organic matter had vital force that confers properties of life to non-living matter
BUT: he had left the flasks unsealed after bioling

17. Lazzaro Spallanzani (1729-1799)
Air carries germs to broth and boiling kills the existing ones
Suppoters of SG:
Compounds essential with the generation of life were destroyed by heating!!
sealing prevents air that is necessary for spontaneous generation

18. Louis Pasteur (1822-1895) Observations:
John Tyndall: Organisms retained on cotton filters resemble microorganisms in contaminated foods
Microorganisms are found in the air
Microorganism in air settle on the surfaces

19. Pateur’s Swan neck flasks could supply air but could also trap ambient germs from entering broth

20. Pasteur Refutes the Spontaneous Generation

21. Pasteur Refutes the Spontaneous Generation
ambient germs are necessary for promoting growth
principle of sterility and aseptic work is important

22. The Role of Microorganisms in Disease
For over 17 centuries the Galenism (Greek physician B.C.) was predominant view for diseases according to which,
Diseases are due to imbalances in 4 humors: blood, phlegm, yellow bile and black bile)

23. Recognition of the Relationship between Microorganisms and Disease
Agostino Bassi ( )
showed that a disease of silkworms was caused by a fungus

24. More evidence… M. J. Berkeley (ca. 1845) Heinrich de Bary (1853)
demonstrated that the great Potato Blight of Ireland was caused by a water mold
Heinrich de Bary (1853)
showed that fungi caused cereal crop diseases
Louis Pasteur
showed that the pébrine disease of silkworms was caused by a protozoan Nosema bombycis

25. Other evidence… Joseph Lister (1827-1912) provided indirect evidence
used diluted carbolic acid (phenol) to wash surgical devices and wash wounds
developed the principles of aseptic surgery
his patients had fewer postoperative infections
Disease frequency dropped in his hospital

26. Final proof… Robert Koch (1843-1910)
established the relationship between Bacillus anthracis and anthrax (Black Death plague)
used criteria developed by his teacher Jacob Henle ( )
these criteria now known as Koch’s postulates
Read more about R. Koch. Check literature section

27. Microorganisms and Diseases Robert Koch
Observations :
The microorganism (Bacillus anthracis) is found only in the infected animals and not in healthy animals.
Infected animals pass the disease to healthy ones
The microorganism found outside of the animal could infect healthy animals

28. Koch’s experiment Anthrax:
Injected mice with B.anthracis, mice got sick
Took spleen from infected mice and grew the anthrax bacillus in a rich medium
Injected healthy mice with spores or the cells
Mice developed anthrax
Independently, similar experiments done by Pasteur

29. Koch’s postulates
The microorganism must be present in every case of the disease but absent from healthy individuals
The suspected microorganism must be isolated from infected individuals and grown in a pure culture
The same disease must result when the isolated microorganism is inoculated into a healthy host
The same microorganism must be isolated again from the diseased host

30. Questions:
Can Koch’s Postulates be applied to all microorganisms that cause disease?
How can you apply Koch’s postulates to viruses and viral diseases?
How can one apply Koch’s postulates to non-cultivable microorganisms?

31. The Development of Techniques for Studying Microbial Pathogens
Koch’s work led to discovery or development of:
agar
Petri dish
nutrient broth and nutrient agar
methods for isolating microorganisms in pure culture

32. The Pure Cultures and Isolation of Single Colonies
Koch :
Observation: Slices of potato when exposed to air, will generate large number of bacteria (colonies) of different sizes, colours and forms
Colonies

33. Problem: Not all bacteria are able to grow on potatoes!
Solution :
Koch used gelatin as a means for solidification of rich culture media.
He formulated various culture media

34. Disadvantages of Gelatin
Gelatin liquefaction: It is digested by various microorganisms eg. gelatinase positive enterococci and streptomyces
Low melting temperature: It is in the liquid state above the temperature of 28oC.

35. Agar
Gracilaria (red seaweeds)
Polysaccharide derived from the cell walls of a red algae (Rhodophyta)
A polysaccharide polymer that contains 3,6-anhydrogalactose, 2-O-methyl-α-l-galactopyranose and 6-O-methyl agarobiose
Solid at >37oC.
Melts at 100oC.
Not digested by most bacteria

36. Conclusion:
A unique cells of different bacteria can grow on agar medium to form a single colony.
A single colony will generate identical colonies (pure colony)
Cultures grown from pure colonies are called pure cultures

37. The golden age of microbiology (1857-1914)
Many disease producing organisms discovered
Microbial metabolism studies undertaken
Microbiological techniques refined
A better understanding of the role of immunity and ways to control and prevent infection by microbes

38. Other developments… Charles Chamberland (1851-1908)
developed porcelain bacterial filters used by Ivanoski and Beijerinck to study tobacco mosaic disease
determined that extracts from diseased plants had infectious agents present which were smaller than bacteria and passed through the filters
Infectious agents were eventually shown to be viruses

39. Immunological Studies
Edward Jenner ( )
used a vaccination procedure to protect individuals from smallpox
NOTE: this preceded the work establishing the role of microorganisms in disease

40. Other developments… Pasteur and Roux Pasteur and his coworkers
discovered that incubation of cultures for long intervals between transfers caused pathogens to lose their ability to cause disease (attenuation)
Pasteur and his coworkers
developed vaccines for chicken cholera, anthrax, and rabies

41. More developments…
Emil von Behring ( ) and Shibasaburo Kitasato ( )
developed antitoxins for diphtheria and tetanus
evidence for humoral immunity
Elie Metchnikoff ( )
discovered bacteria-engulfing, phagocytic cells in the blood (phagocytosis)
evidence for cellular immunity (CMI)

42. The Development of Industrial Microbiology and Microbial Ecology
Louis Pasteur
demonstrated that alcohol fermentations and other fermentations were the result of microbial activity
developed the process of pasteurization to preserve wine during storage

43. Additional Developments…
Sergei Winogradsky ( ) and Martinus Beijerinck ( )
studied soil microorganisms and discovered numerous interesting metabolic processes (e.g., nitrogen fixation)
pioneered the use of enrichment cultures and selective media

44. Summary of Keynotes Advances in Microbiology needed
Technological advances, new observation
Resolution against SG
Establishment of “Germ theory”
Furthering techniques: Culturing and isolation of pure colonies
Application