1. Chapter 1: Microbiology—The Science

2. 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 nonliving entities.
Living microbes are known as cellular microbes or microorganisms; examples include bacteria, archaea, some algae, protozoa, and some fungi.
Nonliving microbes are known as acellular microbes or infectious particles; examples include viroids, prions, and viruses.
Microbes are ubiquitous (i.e., they are found virtually everywhere).

3. Acellular and Cellular Microbes

4. What Is Microbiology? (cont.)
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.

5. What Is Microbiology? (cont.)
Microbes that live on and in our bodies are referred to as our indigenous microbiota
Most of these are beneficial by preventing pathogen growth or secreting beneficial materials
i.e. E. coli
Lives in human intestinal tract
Produces Vitamin K and B1
Some members of our indigenous microbiota 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

6. Microbial Disease Two categories of microbial disease
Infections disease
Results when a pathogen colonizes the body and subsequently causes disease
The leading cause of disease in the world and third leading cause of death in the US
Microbial intoxication
When a person that ingests a toxin (poisonous substance) that has been produced by a microbe
Most heat treatment kills microbes, but the toxin remains

7. Categories of Diseases Caused by Pathogens

8. Why Study Microbiology?
Microbes 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.
Microbes contribute more oxygen to our atmosphere than plants
Microorganisms are involved in the decomposition of dead organisms and waste products.
Saprophytes are organisms that live on dead and/or decaying organic matter.
Aids in fertilization
The use of microbes to clean up toxic wastes and other industrial waste products is known as bioremediation.
Usually these are genetically engineered

9. Microbes as Saprophytes

10. Why Study Microbiology? (cont.)
Algae and bacteria serve as food for tiny animals; they are important links in food chains.
Plankton serves as the starting point for many 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 the scientists learned about microbial cells, the more they learned about cells in general.

11. Microbes and the Food Chain

12. Microbes and Nitrogen Fixation
Many microbes play essential roles in various elemental cycles, such as the carbon, nitrogen, oxygen, sulfur, and phosphorus cycles.
Important to farms and replenishment of nutrients by the breakdown of organic material into inorganic nutrients

13. Why Study Microbiology? (cont.)
Microbes are used in many industries, such as food, beverage, chemical, and antibiotic industries and in genetic engineering.
Antibiotic—substance produced by a microbe effective in killing or inhibiting the growth of other microbes
In genetic engineering, a gene(s) from one organism is 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).
Allows for insulin, vaccines, growth hormones, etc. production
The use of living organisms or their derivatives to make or modify useful products or processes is called biotechnology.

14. Infectious disease and health care
Anyone pursing a career in healthcare must be aware of:
Infectious disease
Source of disease
Transmission of disease
Protection against disease for yourself and other patients
Prevention is key
Use sterile, aseptic, or antiseptic techniques
Infectious disease and health care
Anyone pursuing a career in a healthcare profession must be aware of infectious disease, their source, how they are transmitted, and how to protect yourself and the patient
To prevent the spread of infection sterile, aseptic, and antiseptic techniques are used

15. First Microorganisms on Earth
Fossils of primitive microorganisms date back about 3.5 billion years.
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.

16. Pioneers in the Science of Microbiology
Anton van Leeuwenhoek (1632–1723)
“Father of Microbiology”
Not a trained scientist!
Made many simple single-lens microscopes as a hobby – the skill was lost when he died
Observed “animalcules” (bacteria and protozoa)
Examined any sample he could
Send observations to Royal Society of London
In late 17th century, he convinced scientist of the existence of microbes

17. Origins of Microbes Abiogenesis Theory of Spontaneous generation
Life can arise spontaneously from non-living material
Decaying corpses, soil and swamp gases
Debated for 200 years before being disproved and replaced with biogenesis
Biogenesis
Life can only arise from preexisting life
Proposed by Rudolf Virchow
After the discovery of microbes, scientists began to speculate of their origin
Abiogenesis or the theory of spontaneous generation
The idea that life can arise spontaneously from non-living material such as decaying corpses, soil and swamp gases
Discuss fly and meat experiment conducted to show changes in theory over time
This theory was debated for 200 years and later disproved and replaced with biogenesis
Life can only arise from preexisting life
Proposed by Rudolf Virchow

18. Pioneers in the Science of Microbiology (cont.)
Louis Pasteur (1822–1895)
French chemist who made numerous contributions to microbiology
Considered to be the founder of microbiology and a cornerstone of modern medicine
Investigated different fermentation products
Developed the pasteurization process
Heating liquid to a desired temperature for a set amount of time to kill pathogens
Helped disprove the theory of spontaneous generation
Discovered life forms that could exist without oxygen
Anaerobes – organisms that do not require oxygen
Aerobes – organisms that require oxygen

19. Pioneers in the Science of Microbiology (cont.)
Louis Pasteur (1822–1895)
Developed several vaccines
Chicken cholera
Anthrax
Swine erysipelas
Rabies
Prevent Rabies in dogs
Treat rabies in humans
Contributed to the germ theory of disease
The theory that specific microbes cause specific infections
Helped bring about changes in hospitals to prevent the spread of disease

20. Pioneers in the Science of Microbiology (cont.)
Robert Koch (1843–1910)
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 solid media
Allowed for the growth of pure cultures
Discovered the bacterium that causes TB and cholera
His findings led to the development of the TB skin test
Developed Koch’s postulates
Experimental procedure to prove a specific microbe causes a specific infection

21. 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.

22. Koch’s Postulates (cont.)

23. 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.

24. Exceptions to Koch’s postulate
Obligate intracellular pathogens
Species specific pathogens
Synergistic or polymicrobial infections
Pathogen alterations in vitro
Diseases not caused by microbes
Exceptions
Some pathogens do not grown in artificial growth media (including viruses, rickettsia, chlamydias, and the bacteria that cause leprosy and syphilis) – the obligate intracellular pathogens can only multiply and survive within a living host cell
Many pathogens are species specific (only infect only species of animal) so it is not always possible to fine a laboratory animal that can be infected with a pathogen that only causes human disease
Since human experimentation is not widely practiced, scientists must reside on growing human cell cultures and infecting them
Synergistic infections or polymicrobial infections are caused by the combined effects of two or more different microbes and can be hard to reproduce in the lab
Pathogens are altered when grown in vitro (in the lab causing them to be less or non-pathogenic
Not all disease are caused by microbes, instead they can be caused by dietary deficiencies (scurvy) , inheritance (sickle cell anemia), or malfunction of an organ or system (diabetes)

25. 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