1. Microbiology for the Health Sciences Chapter 1
Microbiology for the Health Sciences Chapter 1. Microbiology: The Science

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

3. What is Microbiology? Biology is the study of living organisms
Microbiology is the study of very small living organisms
Microorganisms are ubiquitous (they are everywhere!)
Categories of microorganisms include:
Viruses
Bacteria
Archaeans
Protozoa
Some algae and fungi

4. Family Tree of Microorganisms

5. What is Microbiology?
Viruses are technically infectious agents or particles
“Germs” are the microorganisms that cause disease
Disease-causing microorganisms are technically pathogens
Microorganisms that do not cause disease are nonpathogens

6. Why Study Microbiology?
Microorganisms live on and in our bodies (indigenous microflora)
Some microorganisms are opportunistic pathogens
Microorganisms are essential for life on this planet
Microorganisms are involved in decomposition of dead organisms and waste (decomposers and saprophytes)
Algae and bacteria serve as food for tiny animals
Microorganisms participate in bioremediation and genetic engineering
Microorganism are involved in elemental cycles
Microorganisms aid in digestion of food
Microorganisms are used in the food and beverage industry

7. Microbes as Saprophytes

8. Microbes and Nitrogen Fixation

9. Why Study Microbiology?
Some microorganisms produce antibiotics used to treat diseases
Microbes are essential in the field of genetic engineering
Microbes are used as “cell models”
Microorganisms cause two categories of disease:
Infectious diseases
Microbial intoxications

10. Categories of Diseases

11. First Microorganisms on Earth
Fossils of primitive microorganisms date back about 3.5 billion years ago.
Candidates for the first microorganisms on earth are archaeans 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.

12. 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)

13. 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

14. Pioneers in the Science of Microbiology
Robert Koch ( )
German physician who made numerous contributions to microbiology
Significant contribution to germ theory of disease
Discovered that B. anthracis produced spores
Developed method of fixing and staining bacteria
Developed methods to cultivate bacteria

15. Koch’s Postulates
A particular microorganism must be found in all cases of the disease and must not be present in healthy animals or humans.
The microorganism must be isolated from the diseased animal or human and grown in pure culture in the laboratory.
The same disease must be produced when microorganisms from the pure culture are inoculated into healthy susceptible lab animals.
The same microorganism must be recovered from the experimentally infected animals and grown again in pure culture.

16. Koch’s Postulates

17. Koch’s Postulates (continued)
If an organism fulfills Koch’s postulates it is proven to be the cause of that particular infectious disease.
Koch’s Postulates helped to prove the germ theory of disease
Koch gave a tremendous boost to the development of microbiology by stressing lab culture and identification of microorganisms
Circumstances do exist in which Koch’s Postulates cannot be fulfilled.

18. Careers in Microbiology
A microbiologist is a scientist who studies microorganisms.
There are many career fields within the science of microbiology – 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, immunology, and production of vaccines.

19. Review of Key Points
Microorganisms, also called microbes, include viruses, bacteria, archaeans, certain algae, protozoa, and certain fungi
Viruses are often referred to as “infectious agents” or “infectious particles”
Microorganisms are ubiquitous; they are everywhere!
Only a small percentage of known microbes cause disease; there are pathogens, nonpathogens and opportunistic pathogens

20. Review of Key Points (continued)
Microorganisms play essential roles in various elemental cycles
Decomposers and saprophytes play important roles in the decomposing of dead animals and plants and organic wastes
Many microbes are used in various industries, such as food, beverage, chemical and antibiotic industries. The use of microbes in industry is known as biotechnology.