1. Chapter 1

2. What is microbiology
Study of organisms too small to be seen by the unaided eye – Microorganisms
Relatively simple in their construction, mostly unicellular
No distinct tissues

3. The Importance of Microorganisms
Microbes exceed every other groups of organisms
Found everywhere (ubiquitous) – ice capped mountains, bottom of the ocean
Air, water, soil
Inside us – normal flora – gastrointestinal, genitourinary, respiratory tract, on the skin
Source of nutrients, some carry out photosynthesis
Unicellular algae – bottom of the food chain

4. Aquatic environments. Unicellular algae
bottom of the food chain.
Unicellular algae > tiny fish > large fish > shark.
Algae are autotrophs. They use CO2 and water to make sugar.
Soil microbes are involved in recycling chemical elements.
Breakdown cellulose and release CO2.
Making food products (yogurt, cheese, bread). Yeast + flour > dough

5. Small ball of dough -----large ball of dough
Therapeutic substances – genetic engineering is used to force E. coli to make human insulin.
Bioremediation – microbes are used to clean up chemical pollutants (oil spills) in the environment.
Insecticide – BT toxin is sprayed on plants.
Sewage treatment – breakdown organic matter to produce methane.

6. Harmful aspects
Tuberculosis, Lyme disease
Spoilage of food products.
Milk sour. Lactose --- acids.

7. Members of the microbial world
Procaryotic cells – pre-nucleus
DNA is not surrounded by a membrane
Eucaryotic cell – true nucleus
DNA is surrounded by a membrane

8. Classification of organisms
1969 Robert whittaker
5 kingdom system
Classification based on
Cell type - prokaryotic/eukaryotic
Cellular organization – unicellular/multicellular
Nutritional requirements – photosynthetic/nonphotosynthetic

9. Classification of organisms
Prokaryotae (monera) – procaryotic organisms – bacteria
Protista - protozoa
Fungi – Yeasts and molds
Plant – ferns, trees, flowering plants
Animal – worms, insects, vertebrates

10. 3 domains
Ribosomal RNA sequence
Archaea, Bacteria, Eukarya
Bacteria – procaryotic
Normal flora, pathogens
Peptidoglycan

11. Archaea
Procaryotic
Unique ribosomal RNA sequence
Unusual, extreme environments
Salt lakes, dead sea
Do not have peptidoglycan cell wall
Pseudomurein
No pathogenic species known

12. viruses Acellular Obligate intracellular parasites
Either have DNA or RNA
No plasma membrane, cytoplasm

13. History of microbiology
1665 Robert Hooke – plant materials (leaves and stems). Little boxes – cells.
1673 – 1723 Anton van Leeuwenhoek observed microbes under the microscope.

14. Discovery of Microorganisms
Antony van Leeuwenhoek ( )
first person to observe and describe microorganisms accurately
Figure 1.3 (a)

15. Figure 1.3 (b) and (c)

16. Rain water, scrapings from his teeth.
Called the microbes animalcules.
Spontaneous generation theory – life could arise from nonliving matter.
Decaying meat could give birth to maggots (larvae of flies)

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

18. Fine net
No maggots

19. But could spontaneous generation be true for microorganisms?
John Needham ( )
his experiment:
mutton broth in flasks  boiled sealed
results: broth became cloudy and contained microorganisms
Lazzaro Spallanzani ( )
broth in flasks sealed  boiled
results: no growth of microorganisms

20. Needham 1745

21. Louis Pasteur (1822-1895) his experiments
placed nutrient solution in flasks
created flasks with long, curved necks
boiled the solutions
left flasks exposed to air
results: no growth of microorganisms

22. CO 01

23. Pasteur’s experiment S shaped curve S shaped curve S shaped curve

24. Germ theory of disease Belief microbes could cause diseases
Before Pasteur’s time people thought a disease was a punishment for someone’s misdeeds.
1850s Pasteur discovered fermentation.
Yeasts broke down sugars in grapes to release alcohol and CO2
If microbes could cause changes in grapes, they could cause changes in humans and animals
Robert Koch proved the germ theory of disease

25. Fig. 1.6

26. Drew blood from the animals that had died of the disease.
Isolated a rod-shaped bacterium (isolate #1)
Grew bacterium in the lab and obtained a pure culture of the bacterium.
Injected bacterium into healthy animals.
They got sick and died. He isolated rod shaped bacterium from these animals (isolate #2)

27. Compared the 2 isolates and found that they were identical.
Anthrax. Bacillus anthracis.
The above steps are known as Koch’s postulates.
They are used even today to determine the causative agent of a mysterious infectious disease.

28. 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 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.

29. 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

30. 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

31. Immunological Studies
Edward Jenner (1798)
used a vaccination procedure to protect individuals from smallpox
Cowpox materials from cowpox lesions to protect people from snallpox.

32. 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

33. 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

34. The Scope and Relevance of Microbiology
importance of microorganisms
first living organisms on planet
live everywhere life is possible
more numerous than any other kind of organisms
global ecosystem depends on their activities
influence human society in many ways

35. Microbiology has basic and applied aspects
Basic aspects are concerned with individual groups of microbes, microbial physiology, genetics, molecular biology and taxonomy
Applied aspects are concerned with practical problems – disease, water, food and industrial microbiology

36. Microbiology actually represents many fields of study
Many specialties
Examples
medical microbiology is concerned with diseases of humans and animals
immunology is concerned with how the immune system protects a host from pathogens

37. More fields…
microbial ecology is concerned with the relationship of organisms with their environment
microbial genetics and molecular biology are concerned with the understanding of how genetic information functions and regulates the development of cells and organisms

38. The Future of Microbiology: Challenges and opportunities for future microbiologists
infectious disease
new and improved industrial processes
microbial diversity and microbial ecology
less than 1% of earth’s microbial population has been cultured

39. Easier to grow
Results can be obtained faster
Easier to manipulate their environment and their DNA
Most of the concepts and processes in biology are first discovered in microbes
Gave foundation that helped scientists to discover the processes in other organisms including humans