1. BIOL 3340

2. Chapter 1
The History
and
Scope of Microbiology

3. The Importance of Microorganisms
medical and most populous group of organisms and are found everywhere on the planet
play a major role in recycling essential elements
source of nutrients and some carry out photosynthesis
benefit society by their production of food, beverages, antibiotics and vitamins
causative agents of some important diseases

4. What is Microbiology?
generally defined as the study of organisms too small to be clearly seen by the unaided eye (i.e., microorganisms)
these organisms are relatively simple in their construction and lack highly differentiated cells and distinct tissues

5. Members of the Microbial World
procaryotic cells lack a true membrane-delimited nucleus
eucaryotic cells have a membrane-enclosed nucleus, are more complex morphologically and are usually larger than procaryotic cells

6. Procaryotes most are single-celled
most have peptidoglycan in cell wall
can survive broad range of environments
most are non-pathogenic and play major role in nutrient recycling

7. …….. Eucaryotes animals, plants and eucaryotic microorganisms
microorganisms include protists (unicellular algae, protozoa, slime molds and water molds) and fungi
most are larger than procaryotic cells

8. …….. Viruses
acellular
smallest of all microbes (smallest is 10,000 times smaller than a typical bacterium

9. Importance of Microorganisms
first living organisms on planet
live almost everywhere life is possible
more numerous than any other kind of organisms
global ecosystem depends on their activities
influence human society in many ways

10. Discovery of Microbes Antony van Leeuwenhoek (1632-1723)
first person to observe and describe microorganisms accurately
Developed early microscope
First to observemicrobes:“animalcules”

11. …….. The Conflict over Spontaneous Generation
Spontaneous generation: living organisms can develop from nonliving or decomposing matter
1. Francesco Redi ( ):
disproved spontaneous generation for large animals
showed that maggots on decaying meat came from fly eggs

12. 2. John Needham ( ):
his experiment : mutton broth in flasks  boiled sealed with cork :
broth became cloudy & contained microorganisms
3. Lazzaro Spallanzani ( ):
his experiment: boiled seeds in flasks & water sealed  boiled:
no growth of microorganisms in sealed & open flasks had animicules

13. …….. Louis Pasteur (1822-1895) 4. Pasteur Mid to late-1800s
French chemist and a “founder” of the modern science of microbiology
Settled the Spallanzani-Needham debate with the “swan-necked flask” experiment & put to rest the Spontaneous generation theory

14. boiled the solutions & left flasks exposed to air
……..Pasteur
boiled the solutions & left flasks exposed to air
results: no growth of microorganisms
placed nutrient solution in flasks with long, curved necks

15. …….. Pasteur

16. …….. Pasteur
Pasteur laid the foundation of aseptic techniques, techniques that prevent contamination by unwanted microbes. These techniques are based on Pasteur’s idea that microbes can be killed by heat and that procedures can be designed to inhibit the access of airborne microbes to nutrient environment.
He dispprove the idea that microorganisms spontaneously generated from non-living matter through mystical forces is one of the greatest contributions of Pasteur in science

17. Final Blow to Theory of Spontaneous Generation
5. John Tyndall ( ):
demonstrated that dust carries microorganisms
showed that if dust was absent, nutrient broths remained sterile, even if directly exposed to air
Demonstrated directly that the growth of microbes in contaminated flasks was due to microbial cells from airborne dust particles, not from spontaneous generation

18. Theory of biogenesis Vs Spontaneous generation :
The theory of biogenesis states that living things can only arise from living things and cannot be spontaneously generated.
The Spontaneous generation hypothesis proposed by scientists to explain the origin of the “animalcules” observed by Antoni van Leeuwenhoek in his magnifying lenses had received wide acceptance all over Europe from Antoni’s time until the time of Louis Pasteur.

19. The Golden Age of Microbiology (1857-1914)
Many disease producing organisms were 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

20. The Role of Microorganisms in Disease
was not immediately obvious
establishing connection depended on development of techniques for studying microbes
once established, led to study of host defenses - immunology

21. Recognition of the Relationship between Microorganisms and Disease
Agostini Bassi ( ):
showed that a disease of silkworms was caused by a fungus
M. J. Berkeley (ca. 1845):
demonstrated that the great Potato Blight of Ireland was caused by a water mold
Heinrich de Bary (1853):
showed that smut and rust fungi caused cereal crop diseases
Louis Pasteur :
showed that the pébrine disease of silkworms was caused by a protozoan

22. Other evidences Joseph Lister:
provided indirect evidence that microorganisms were the causal agents of disease
developed a system of surgery designed to prevent microorganisms from entering wounds as well as methods for treating instruments and surgical dressings
his patients had fewer postoperative infections

23. Robert Koch (1843-1910) Robert Koch:
Established the relationship between Bacillus anthracis and anthrax
Develop the Koch’s postulates:
used today to establish the link between a particular microorganism and a particular disease

24. ..Koch Postulates
1.Similar pathogen must be present in every case of the disease.
2. The pathogen should be isolated from the diseased animal host and grown in pure culture.
3. A healthy laboratory animal inoculated with the pathogen taken from the pure culture must acquire the disease.
4. The pathogen must be isolated from the inoculated animal and should be the same from the microbe in the original animal.

25. 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

26. Immunological Studies
Edward Jenner (ca. 1798)
used a vaccination procedure to protect individuals from smallpox
Pasteur and Roux :
discovered that incubation of cultures for long intervals between transfers caused pathogens to lose their ability to cause disease
Pasteur and his coworkers
developed vaccines for chicken cholera, anthrax, and rabies

27. Emil von Behring (1854-1917) and Shibasaburo Kitasato (1852-1931)
developed antitoxins for diphtheria and tetanus
evidence for humoral immunity
Elie Metchnikoff ( )
discovered bacteria-engulfing, phagocytic cells in the blood
evidence for cellular immunity

28. 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

29. …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

30. Aseptic techniques

31. …….. Pure Culture Technique

32. Bibliography http://en.wikipedia.org/wiki/Scientific_method
Lecture PowerPoints Prescott’s Principles of Microbiology-Mc Graw Hill Co.