1. The Scope of Microbiology (1)
Microbiology: the specialized area of biology that deals with organisms too small to be seen with the naked eye
Microorganisms or microbes
Germs, viruses, or agents
“Bugs”

2. The Scope of Microbiology (2)
Major groups of microorganisms:
Bacteria
Algae
Protozoa
Helminths
Fungi
Viruses: noncellular, parasitic, protein-coated genetic elements that cause harm to host cells

3. The Scope of Microbiology (3)
Microbes are easy and difficult to study
Reproduce rapidly, large populations can be grown in the laboratory
Can’t be seen directly, must be analyzed through indirect methods in addition to using microscopes

4. The Scope of Microbiology (4)
Microbiologists study:
Cell structure and function
Growth and physiology
Genetics
Taxonomy and evolutionary history
Interactions with living and nonliving environment

5. Branches of Microbiology
Medical Microbiology
Deals with microbes that cause diseases in humans and animals
Public Health Microbiology and Epidemiology
Monitor and control the spread of diseases in communities
USPHS, CDC, WHO

6. Branches of Microbiology
Immunology
Complex web of protective substances and cells produced in response to infection
Includes vaccination, blood testing, and allergy
Role of the immune system in cancer and autoimmune diseases
Industrial Microbiology
Safeguards our food and water
Biotechnology
Microbes used to create amino acids, beer, drugs, enzymes, and vitamins

7. Branches of Microbiology
Agricultural Microbiology
Relationships between microbes and domesticated plants and animals
Plant specialists, animal specialists
Environmental Microbiology
Study the effect of microbes on the earth’s diverse habitats
Aquatic, soil, and geomicrobiology, and astrobiology

8. The Impact of Microbes on Earth
Eukary: true nucleus
Cells with a nucleus are classified as eukaryotes
Prokary: pre nucleus
Bacteria and archaea do not have a nucleus and have been traditionally classified as prokaryotes
This classification is no longer used because bacteria and archaea are so distant genetically

9. The Impact of Microbes on Earth (3)
Bacteria are ubiquitous. They are found:
deep in the earth’s crust
polar ice caps
oceans
inside the bodies of plants and animals

10. The Impact of Microbes on Earth (4)
Evolution: the accumulation of changes that occur in organisms as they adapt to their environments
Theory of Evolution:
Documented every day in all corners of the planet
An observable phenomenon testable by science
A label for a well-studied and well-established natural phenomenon

11. Microbial Involvement in Shaping Our Planet
Microbes are deeply involved in the flow of energy and food through the earth’s ecosystems
Bacteria: anoxygenic photosynthesis
The production of oxygen by microbes allowed species diversification
Photosynthetic microorganisms (bacteria and algae) account for more than 70% of the earth’s photosynthesis, contributing the majority of the oxygen to the atmosphere

12. Microbial Involvement in Shaping Our Planet
Decomposition:
Breakdown of dead matter and wastes
Accomplished by bacteria and fungi
(b) © Michel & Christine Denis-Huot/Science Source

13. Human Use of Microorganisms (1)
Humans have been using microorganisms for thousands of years to improve life and even shape civilizations
Yeast for production of bread, wine, and beer
Other fungi used for cheese production
Moldy bread used in Egypt to treat wounds

14. Human Use of Microorganisms (2)
Biotechnology:
Manipulation of microorganisms to make products in an industrial setting
Genetic Engineering:
Manipulates the genetics of microbes, plants, and animals for the purpose of creating new products and genetically modified organisms (GMOs)
(a) NREL/US Department of Energy/Dennis Schroeder
(b) © Bloomberg via Getty Images

15. Human Use of Microorganisms (3)
Recombinant DNA technology:
Techniques that allow the transfer of genetic material from one organism to another and deliberately alter DNA
Bioremediation:
Introduction of microbes into the environment to restore stability or to clean up toxic pollutants
(c) © Accent Alaska.com/Alamy

16. Infectious Diseases and the Human Condition
Pathogen: any agent such as a virus, bacterium, fungus, protozoan, or helminth that causes disease
Nearly 2000 different microbes can cause disease

17. Infectious Diseases and the Human Condition
New (emerging) diseases as well as older (reemerging) diseases are increasing
Ebola, AIDS, hepatitis C, and viral encephalitis
Polio, leprosy, and parasitic worm diseases have largely been eradicated

18. Infectious Diseases and the Human Condition
Certain diseases once considered noninfectious are now found to be caused by microbes:
Gastric ulcers caused by Helicobacter pylori
Link between certain cancers and bacteria and viruses
Cocksackie virus has been associated with diabetes and schizophrenia
Multiple sclerosis, OCD, coronary artery disease, obesity linked to chronic microbial infections

19. Infectious Diseases and the Human Condition
First Golden Age of Microbiology: “obvious” diseases were characterized and cures or preventions were devised
Today, we are discovering the subtler side of microorganisms and the quiet, slow, destructive diseases they cause
Female infertility caused by Chlamydia infection
Liver cancer (hepatitis viruses) and cervical cancer (human papillomavirus)

20. Infectious Diseases and the Human Condition
An increasing number of patients with weakened immune systems are subject to infections by common microbes not pathologic to healthy people Drug-resistant microbes also contribute to the increase in infectious disease

21. General Characteristics of Microorganisms
Bacterial and Archaeal cells:
About 10x smaller than eukaryotic cells
Lack organelles: small, double-membrane-bound structures that perform specific functions
The majority of microorganisms are single-celled (all bacterial and archaeal and some eukaryotes)

22. Cell Structure

23. Five Types of Microorganisms
Top Left) CDC; (Middle Left) CDC/Dr. Lucille K. Georg; (Bottom Left) © Nancy Nehring/E+/Getty Images RF; (Bottom Center) CDC/Janice Carr; (Bottom Right) CDC

24. Lifestyles of Microorganisms
Majority of microorganisms:
Live in habitats such as soil and water
Are relatively harmless and often beneficial
Derive food and other factors from the nonliving environment
Parasites:
Harbored and nourished by the host
Cause damage and disease in the host

25. Development of the Microscope
Robert Hooke:
First observations of microbes in the 1600s
Antonie van Leeuwenhoek:
Made a crude microscope to examine threads in fabrics
Made drawings of what he called “animalcules” in rainwater and scraped from his teeth
(a) © Biophoto Associates/Science Source; (b) CDC/Dr. Lucille K. Georg
© Tetra Images/Alamy RF

26. Development of Aseptic Techniques
Robert Koch:
Linked a specific microorganism with a specific disease
Dr. Oliver Wendell Holmes and Dr. Ignaz Semmelweis:
Showed that women became infected in the maternity ward after examinations by physicians who had been working in the autopsy rooms

27. Development of Aseptic Techniques
Joseph Lister:
First to utilize hand washing and misting operating rooms with antiseptic chemicals
Techniques became the foundation for modern microbial control still in use today
© Bettmann/Corbis

28. Discovery of Pathogens and the Germ Theory of Disease
Pasteur:
Invented pasteurization
Showed that human diseases could arise from infection
Robert Koch:
Established a series of proofs that verified the germ theory of disease

29. Binomial System of Nomenclature
A combination of the generic (genus) and species name
The genus name is always capitalized and the species name begins with a lower case letter
Both names should be italicized when in print or underlined when written by hand
Abbreviations:
The genus name can be abbreviated to save space or if the genus name has already been stated
Example: Staphylococcus aureus can be abbreviated as S. aureus