1. The Science - Introduction
MICROBIOLOGY
Section I
The Science - Introduction
Chapter 1

2. Chapter 1 Outline Introduction What is microbiology?
Why study microbiology?
First microorganisms on Earth
Earliest known infectious diseases
Pioneers in the science of microbiology
Careers in microbiology
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3. What is Microbiology? Biology is the study of living organisms
Microbiology is an advanced biology course
Microbiology is the study of microbes, which are extremely small (microscopic) living organisms and certain non-living entities
Living microbes are known as cellular microbes or microorganisms; examples include bacteria, archaea, some algae, protozoa, and some fungi
Non-living microbes are known as acellular microbes or infectious particles; examples include viroids, prions, and viruses
Microorganisms are ubiquitous (they are found virtually everywhere)
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4. Acellular and Cellular Microbes
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5. What is Microbiology?
The microbes that cause disease are sometimes referred to as “germs”
The scientific term for disease-causing microbes is pathogens
Microbes that do not cause disease are called nonpathogens; the vast majority of microbes are nonpathogens
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6. What is Microbiology?
Microbes that live on and in our bodies are referred to as our indigenous microflora
Some members of our indigenous microflora are opportunistic pathogens
Opportunistic pathogens are microbes that can cause disease, but usually do not; they can be thought of as microbes that are awaiting the opportunity to cause disease
Pathogens cause two categories of diseases: infectious diseases and microbial intoxications
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7. Categories of Diseases Caused by Pathogens
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8. Why Study Microbiology?
Microorganisms play significant roles in our lives; they are essential for life on this planet
Photosynthetic algae and bacteria (such as cyanobacteria) produce much of the oxygen in our atmosphere
Microorganisms are involved in the decomposition of dead organisms and waste products
Saprophytes are organisms that live on dead and/or decaying organic matter
The use of microbes to clean up toxic wastes and other industrial waste products is known as bioremediation
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9. Microbes as Saprophytes
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10. Why Study Microbiology?
Many microbes play essential roles in various elemental cycles; e.g., the carbon, nitrogen, oxygen, sulfur, and phosphorous cycles
Algae and bacteria serve as food for tiny animals; they are important links in food chains
Microbes that live in the intestinal tracts of animals aid in the digestion of food and produce beneficial substances
For many years, microorganisms have been used as “cell models”; the more that scientists learned about microbial cells, the more they learned about cells in general
Naturally occurring bioremediation and phytoremediation have been used for centuries. For example, desalination of agricultural land by phytoextraction has a long tradition. Bioremediation technology using microorganisms was reportedly invented by George M. Robinson. He was the assistant county petroleum engineer for Santa Maria, California. During the 1960s, he spent his spare time experimenting with dirty jars and various mixes of microbes.
The use of genetic engineering to create organisms specifically designed for bioremediation has great potential.[5] The bacterium Deinococcus radiodurans (the most radioresistant organism known) has been modified to consume and digest toluene and ionic mercury from highly radioactive nuclear waste.[6]
Most commonly, the process is misunderstood. The microbes are ever-present in any given context—generally referred to as "normal microbial flora". During bioremediation (biodegradation) processes, fertilizers/nutrient supplementation is introduced to the environments, in efforts to maximize growth and production potential. Common misbelief is that microbes are transported and dispersed into an unadulterated environment.
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11. They are important links in food chains
Humans are on the top of the food chain
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12. GLBH Microbiology

13. Microbes and Nitrogen Fixation
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14. Why Study Microbiology?
Microbes are used in many industries; e.g., food, beverage, chemical, and antibiotic industries and in genetic engineering
In genetic engineering, a gene or genes from one organism is/are inserted into a bacterial or yeast cell; the cell that receives the new gene(s) is then capable of producing the gene product(s) coded for by the new gene(s)
The use of living organisms or their derivatives to make or modify useful products or processes is call biotechnology
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15. Typical application of biodispersant to remediate an oil spill
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16. More on Why to Study Microbiology…
Use of microbes as “cell models”
E. Coli is one of the most studied
Microbes cause two categories of diseases:
Infectious disease
This is the leading cause of death in the world and the 3rd leading cause of death in the US (after heart disease and cancer).
Microbial intoxication
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17. GLBH Microbiology

18. First Microorganisms on Earth
Scientists tell us …
Fossils of primitive microorganisms date back about 3.5 billion years ago.
Candidates for the first microorganisms on Earth are archaea and cyanobacteria.
Infectious diseases of humans and animals have existed for as long as humans and animals have inhabited the planet.
Earliest known account of pestilence occurred in Egypt in about 3180 BC.
Studying mummies:
TBC and syphilis
Parasitic worm infections (schistosomiasis, dracunculiasis and tapeworm)
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19. Earliest Observations
Bacteria and protozoa were the first microbes to be observed by humans
Earliest observations recorded in 1665
The earliest microbiologists:
Anton van Leeuwenhoek (1632 – 1723)
Louis Pasteur (1822 – 1895)
Robert Koch (1843 – 1910)
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20. The First Observations
1665: Robert Hooke reported that living things were composed of little boxes, or cells
Ground for the cell theory
1858: Rudolf Virchow said cells arise from preexisting cells
Cell theory: All living things are composed of cells and come from preexisting cells
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21. Pioneers in the Science of Microbiology
Anton van Leeuwenhoek ( )
“Father of Microbiology”
Not a trained scientist!
Made many simple single-lens microscopes
Observed ”animalcules” (bacteria and protozoa)
Made more than 500 of these microscopes.
He wrote to the Royal Soceity of London:
My method for seeing the very smallest animalcules I do not impart to others; nor how to see very many animalcules at one time. This I keep for myself alone.
He did not associated his observations with cause of disease…Such relationships were not established until the work of Louis Pasteur and Robert Koch in the late 19th century.
Speculation of the origin was that life could develop spontaneously from inanimate substances – abiogenesis or spontaneous generation.
This theory was disproved – proving that life can only airse from preexisting life: this is called the theory of biogenesis first proposed by Rudolf Virchow in 1858 (a German scientist).
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22. Pioneers in the Science of Microbiology
Louis Pasteur ( )
French chemist who made numerous contributions to microbiology
Investigated different fermentation products
Developed the pasteurization process
Discovered life forms that could exist without oxygen (anaerobes)
Developed several vaccines, including rabies and anthrax vaccines
His contribution are considred as the foundation of microbiology and a cornersone of modern medicine:
Fermentation of the wine when contaminated with different types of microbes
Yeast convert glucose in grapes to ethyl alcohol (ethanol)
Acetobacter convert glucose to acetic acid (vinegar) that ruin the taste of wine
Blow theory of spontaneous generation (abiogenesis)
Discover form of life without oxygen; clasifyin aerobes (need oxygen) and anaerobes (do not need oxygen)
Develop pasteurization to kill pathogens that can ferment (in that case, the wine). Actually this process only kills the pathogens microbes.
Discover infectious agents that cause silkworm diseases and how to prevent
Significant contribution to the Germ Theory of disease (related specific maicrobe to a disease)
Champion changes in hospital practices to minimize spread of diseases
Developed vaccines to prevent chicken cholera, anthrax, and swine eysipelas. Also vaccine to prevent rabies.
Pasteur Institute in France created in 1888, now extended to a network of Pasteur Institutes. The first foreign in Saigon, Vietnam (Ho Chi Minh City) – one of the directors (Alexandre Emile Jean Yersin) who discovered the bacterium that causes plague; he was a former student of Koch and Pasteur.
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23. Debate on Spontaneous Generation
Francisco Redi (1668) demonstrated that maggots appear on decaying meat only when flies are able to lay eggs on the meat
John Needham (1745) claimed microorganism arise spontaneously from heated nutrient broth
Lazzaro Spallanzani (1765) repeated Needham’s experiments and suggested that it was due to air-microorganisms entering the broth.
Rudolf Virchow (1858) introduced “biogenesis” concept where living cells arise only from preexisting cells.
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24. 1668: Francesco Redi filled 6 jars with decaying meat
Evidence Pro and Con
1668: Francesco Redi filled 6 jars with decaying meat
Conditions
Results
Three jars covered with fine net
No maggots
Three open jars
Maggots appeared
From where did the maggots come?
What was the purpose of the sealed jars?
Spontaneous generation or biogenesis?
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25. 1745: John Needham put boiled nutrient broth into covered flasks
Evidence Pro and Con
1745: John Needham put boiled nutrient broth into covered flasks
Conditions
Results
Nutrient broth heated, then placed in sealed flask
Microbial growth
From where did the microbes come?
Spontaneous generation or biogenesis?
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26. 1765: Lazzaro Spallanzani boiled nutrient solutions in flasks
Evidence Pro and Con
1765: Lazzaro Spallanzani boiled nutrient solutions in flasks
Conditions
Results
Nutrient broth placed in flask, heated, then sealed
No microbial growth
Spontaneous generation or biogenesis?
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27. Evidence Pro and Con
1861: Louis Pasteur demonstrated that microorganisms are present in the air
Conditions
Results
Nutrient broth placed in flask, heated, not sealed
Microbial growth
Nutrient broth placed in flask, heated, then sealed
No microbial growth
Spontaneous generation or biogenesis?
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28. The Theory of Biogenesis
Pasteur’s S-shaped flask kept microbes out but let air in
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Figure 1.3
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29. Fermentation and Pasteurization
Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine
Pasteurization is the application of a high heat for a short time
Figure 1.4
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30. Pioneers in the Science of Microbiology
Robert Koch ( )
German physician who made numerous contributions to microbiology
Made significant contributions to the germ theory of disease
Discovered that Bacillus anthracis produced spores
Developed methods of fixing and staining bacteria
Developed methods to cultivate bacteria
On of his colleagues (R. J. Petri) invented a flat glass dish (known as Petri dish) in which to culture bacteria.
Discovered the bacterium that causes tuberculosis and cholera
Work on tuberculin that is now use for skin test in diagnosing TB.
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31. Koch’s Postulates
A particular microbe must be found in all cases of the disease and must not be present in healthy animals or humans.
The microbe must be isolated from the diseased animal or human and grown in pure culture in the laboratory.
The same disease must be produced when microbes from the pure culture are inoculated into healthy susceptible laboratory animals.
The same microbe must be recovered from the experimentally infected animals and grown again in pure culture.
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32. Koch’s Postulates GLBH 205 - Microbiology
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33. Koch’s Postulates, cont.
If an organism fulfills Koch’s postulates, it has been proven to be the cause of that particular infectious disease
Koch’s Postulates helped prove the germ theory of disease
Koch gave a tremendous boost to the development of microbiology by stressing laboratory culture and identification of microorganisms
Circumstances do exist in which Koch’s Postulates cannot be fulfilled
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34. Exceptions to Koch’s Postulates
Regarding in-vitro grow/culture of pathogen in or on artificial culture media
Some pathogens will not grow in this media
Viruses, rickettsias, chlamydias that are obligate intracellular pathogens
Bacteria causing leprosy and syphilis
Some fastidious microbes (with complex and demanding nutritional requirements)
Some pathogens are species-specific
Synergistc infections are caused by combined effects of two or more different microbes.
Some diseases are not caused by microbes (e.g. nutritional deficiencies
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35. Careers in Microbiology
A microbiologist is a scientist who studies microbes.
There are many career fields within the science of microbiology (e.g., bacteriology, phycology, protozoology, mycology, parasitology, and virology).
Medical Microbiology
Involves the study of pathogens, the disease they cause and the body’s defenses against disease.
Concerned with epidemiology, transmission of pathogens, disease-prevention measures, aseptic techniques, treatment of infectious diseases, immunology, and production of vaccines.
Microbiologist might have a bachelor’s, master, or doctoral degree
Bacteriologist specializes in bacteriology (study of structure, function and activities of bacteria)
Phycologists =>Phycology (algology) = algae / phycologists.
Protozologists
Mycologists
Virologists (and cell biologists) => genetic engineers
Medical microbiology: clinical microbiology and diagnostic microbiology
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36. END OF PRESENTATION

37. Which of the following is the most important element of Koch’s germ theory of disease? The animal shows disease symptoms when
the animal has been in contact with a sick animal.
the animal has a lowered resistance.
a microorganism is observed in the animal.
a microorganism is inoculated into the animal.
microorganisms can be cultured from the animal.
Answer: d
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38. Which of the following statements is the best definition of biogenesis?
Nonliving matter gives rise to living organisms.
Living cells can only arise from preexisting cells.
A vital force is necessary for life.
Air is necessary for living organisms.
Microorganisms can be generated from nonliving matter.
Answer: b
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39. Which of the following is a beneficial activity of microorganisms?
Some microorganisms are used as food for humans.
Some microorganisms use carbon dioxide.
Some microorganisms provide nitrogen for plant growth.
Some microorganisms are used in sewage treatment processes.
all of the above
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40. Which of the following would be the essential function performed by bacteria?
control insect populations
directly provide food for humans
decompose organic material and recycle elements
cause disease
produce human growth hormones such as insulin
Answer: c
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41. Which of the following is an example of bioremediation?
application of oil-degrading bacteria to an oil spill
application of bacteria to a crop to prevent frost damage
fixation of gaseous nitrogen into usable nitrogen
production by bacteria of a human protein such as interferon
all of the above
Answer: a
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42. Which of the following statements is true?
All life requires air.
Only disease-causing organisms require air.
Some microbes do not require air.
Pasteur kept air out of his biogenesis experiments.
Lavoisier was mistaken.
Answer: c
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43. Which of the following statements about E. coli is not true?
E. coli was the first disease-causing bacterium identified by Koch.
E. coli is part of the normal microbiota of humans.
E. coli is beneficial in human intestines.
A disease-causing strain of E. coli causes bloody diarrhea.
none of the above
Answer: a
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44. Robert Koch Developed the microscope Discovered penicillin
Developed the germ theory of disease
First observed cells
Answer: c
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45. Pasteur Disproved spontaneous generation Discovered penicillin
Discovered phagocytosis
Developed aseptic surgery
Answer: a
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46. Who first used microscopes to observe microorganisms?
Koch
Jenner
Pasteur
Van Leeuwenhoek
Answer: d
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47. Who developed a set of postulates to prove that specific microorganisms cause disease?
Jenner
Gram
Pasteur
Koch
Answer: d
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48. Biotechnology can best be defined as
Using living organisms to clean up pollution
Using living organisms to develop desired products
Using living organisms to treat disease
Using living organisms to control pests
Answer: b
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49. GLBH Microbiology