1. Chapter 1 The Main Themes of Microbiology
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2. Microbiology
The study of organisms too small to be seen without magnification
Microorganisms include:
Bacteria
Viruses
Fungi
Protozoa
Helminths (worms)
Algae

3. Microbiological Endeavors
James Gathany/CDC
CDC
Photo courtesy of Sartorius Stedim Biotech
Jack Dykinga, USDA/ARS

4. Origins of Microorganisms
Bacteria-like organisms have existed on earth for about 3.5 billion years
Prokaryotes (pre-nucleus): Simple cells
Eukaryotes (true nucleus): Complex cells
Humans
appeared.
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Mammals
appeared.
Cockroaches,
termites
appeared.
Probable
origin of
earth
Prokaryotes
appeared.
Eukaryotes
appeared.
Reptiles
appeared.
15 billion
years ago
4 billion
years ago
3 billion
years ago
2 billion
years ago
1 billion
years ago
Present
time

5. Microbial Structure Two cell lines
Prokaryote – microscopic, unicellular organisms, lack nuclei and membrane-bound organelles
Eukaryote – unicellular (microscopic) and multicellular, nucleus and membrane-bound organelles
Viruses - Acellular, parasitic particles composed of a nucleic acid and protein
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(a) Cell Types
(b) Virus Types
Prokaryotic
Eukaryotic
Nucleus
Mitochondria
Envelope
Chromosome
Ribosomes
Capsid
Ribosomes
Nucleic
acid
AIDS virus
Cell wall
Cell
membrane
Flagellum
Flagellum
Cell membrane
Bacterial virus

6. Microbial Diversity: 6 Types of Microbes
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Reproductive spores
Janice Carr/CDC
© Tom Volk
© Charles Krebs Photography
Bacteria: Mycobacterium tuberculosis, a
rod-shaped cell (15,500x).
Fungi: Thamnidium, a filamentous
fungus (400x)
Algae: desmids, Spirogyra filament, and diatoms
(golden cells) (500x).
A single virus particle
CDC
© Yuuji Tsukii, Protist Information Server
CDC
Virus: Herpes simplex, cause of cold
sores (100,000x).
Protozoa: A pair of Vorticella (500x), stalked cells
that feed by means of a whirling row of cilia.
Helminths: Cysts of the parasitic roundworm,
Trichinella spiralis (250x) embedded in muscle.

7. Most bacteria fall between 1 to 10 mm
Microbial Dimensions
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1 mm
Range of
human
eye
Louse
Reproductive structure
of bread mold
Macroscopic
Macroscopic
100 mm
Nucleus
Colonial alga
(Pediastrum)
Amoeba
Range of
light microscope
Red blood cell
White blood cell
10 mm
Most bacteria fall between 1 to 10 mm
in size
1 mm
Rickettsia bacteria
Rod-shaped bacteria
(Escherichia coli)
Coccus-shaped bacteria
(Staphylococcus)
200 nm
Mycoplasma bacteria
Poxvirus
100 nm
AIDS virus
Hepatitis B virus
Range of
electron
microscope
10 nm
Poliovirus
Flagellum
Large protein
1 nm
Diameter of DNA
Require
special
microscopes
Amino acid
(small molecule)
0.1 nm
Hydrogen atom
(1 Angstrom)
Metric Scale
kilometer (km)
hektometer (hm)
dekameter (dam)
meter (m)
decimeter (dm)
centimeter (cm)
millimeter (mm)
micrometer (mm)
nanometer (nm)
Angstrom (Å )
picometer (pm)
1,000
100 10 1. 0, 0, 0,
Log 10
of meters
–1 –2 –3 –4 –5 –6 –7 –8 – –10 –11 –12

8. Microbes in Energy & Nutrient Flow
The flow of energy and food through the earth’s ecosystems
Photosynthesis: Light fueled conversion of carbon dioxide to organic material
Decomposition: Breakdown of dead matter and wastes into simple compounds

9. Concept Check: Which of the following does NOT describe a fungus?
A. Contains a nucleus
Has 80S Ribosomes
Useful in Decomposition
Is photosynthetic

10. Human Use of Microorganisms
Biotechnology: Production of foods, drugs, and vaccines using living organisms
Genetic engineering: Manipulating the genes of organisms to make new products
Bioremediation: Using living organisms to remedy an environmental problem

11. Lifestyles of Microorganisms
Majority live a free existence, are relatively harmless and often beneficial
Some microorganisms have close associations with other organisms
Parasites live on or in the body of another organism called the host and it damages the host.

12. Microbes & Infectious Diseases
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Pathogens: Microbes that do harm
Nearly 2,000 different microbes cause diseases
10 B new infections/year worldwide
12 M deaths from infections/year worldwide
Tetanus 2.5%
Parasitic diseases 2.5%
Miscellaneous 1.5%
Hepatitis B
Respiratory infections
(pneumonia, influenza)
Measles 5%
26% 7% 9%
Malaria
11%
18%
Tuberculosis
17.5%
AIDS
Diarrheal diseases (cholera,
dysentery, typhoid)

13. Top Causes of Death in the United States and Worldwide

14. Historical Foundations of Microbiology
Thousands of microbiologists over 300 years
Prominent discoveries include:
Microscopy
Scientific method
Development of medical microbiology
Microbiology techniques

15. Spontaneous Generation
Spontaneous Generation is an early belief that some forms of life could arise from vital forces present in nonliving or decomposing matter (flies from manure, etc.)
Louis Pasteur eventually disproved spontaneous generation and proved the Theory of Biogenesis - the idea that living things can only arise from other living things

16. Antonie van Leeuwenhoek (1632-1723)
Dutch linen merchant
First to observe living microbes
Single-lens magnified up to 300X

17. Leeuwenhoek’s Work Lens Specimen holder Focus screw Handle
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Lens
Specimen holder
Focus screw
Handle
© Kathy Park Talaro/Visuals Unlimited
© Kathy Park Talaro/Visuals Unlimited

18. Scientific Method
Approach taken by scientists to explain a certain natural phenomenon
Form a hypothesis - a tentative explanation that can be supported or refuted
Deductive approach “If…, then….”
A lengthy process of experimentation, analysis, and testing either supports or refutes the hypothesis
Results must be published and repeated by other investigators.
If hypothesis is supported by a growing body of evidence and survives rigorous scrutiny, it moves to the next level of confidence - it becomes a theory.
If evidence of a theory is so compelling that the next level of confidence is reached, it becomes a Law or principle.

19. Concept Check:
A Scientific Theory has little or no evidence to support it and could be best described as a “best guess”.
A. True
B. False

20. Discovery of Spores and Sterilization
John Tyndall and Ferdinand Cohn each demonstrated the presence of heat resistant forms of some microbes.
Cohn determined these forms to be heat-resistant bacterial endospores.
Sterility requires the elimination of all life forms including endospores and viruses.

21. Using the Scientific Method to Investigate Bacterial Endospores
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Hypothesis
Predictions
Testing
Theory/Principle
Bacterial endospores
are the most resistant
of all cells on earth.
If hypothesis is true,
endospores can survive
extreme conditions
such as:
Compare endospore formers to non-endospore microbes.
Endospores are the only
cells consistently capable of
surviving a wide range of
destructive environmental
conditions. In order to
sterilize, these cells must be
eliminated.
Survival of
endospore former
Survival of
non-endospore former
 temperature (boiling) –/+*
 radiation (ultraviolet) –
 lack of water (drying) –/+
 chemicals –/+
(disinfectants) *Only 1 out of 4 cell types survives.
Endospores
of certain
bacteria
Endospores
Cells without
endospores are
ordinary bacteria,
fungi, animal cells.
Additional tests show that endospores
have thick coverings and protective features
and that endospores are known to survive
over millions of years.

22. Development of Aseptic Techniques
The human body is a source of infection
Dr. Oliver Wendell Holmes – observed that mothers of home births had fewer infections than those who gave birth in hospitals
Dr. Ignaz Semmelweis – correlated infections with physicians coming directly from the autopsy room to the maternity ward
Joseph Lister – introduced aseptic techniques to reduce microbes in medical settings and prevent wound infections
Involved disinfection of hands using chemicals prior to surgery
Use of heat for sterilization

23. The Germ Theory of Disease
Many diseases are caused by the growth of microbes in the body and not by sins, bad character, or poverty, etc.
Two major contributors:
Louis Pasteur and Robert Koch

24. Louis Pasteur ( )
Showed microbes caused fermentation and spoilage
Disproved spontaneous generation of microorganisms
Developed pasteurization
Demonstrated what is now known as Germ Theory of Disease

25. Robert Koch ( )
Established Koch’s postulates - a sequence of experimental steps that verified the germ theory
Identified cause of anthrax, TB, and cholera
Developed pure culture methods

26. Taxonomy Taxonomy: organizing, classifying, and naming living things
Formal system originated by Carl von Linné
Concerned with:
Classification – orderly arrangement of organisms into groups
Nomenclature – assigning names
Identification – determining and recording traits of organisms for placement into taxonomic schemes

27. Levels of Classification
Domain - Archaea, Bacteria, & Eukarya
Kingdom
Phylum or Division
Class
Order
Family
Genus
Species

28. Sample Taxonomy
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Domain: Eukarya (All eukaryotic organisms)
Domain: Eukarya (All eukaryotic organisms)
Kingdom: Animalia
Kingdom: Protista
Includes
protozoa
and algae
Lemur
Sea squirt
Sea star
Phylum: Chordata
Phylum: Ciliophora
Only protozoa
with cilia
Class: Mammalia
Class: Hymenostomea
Single cells with
regular rows of
cilia; rapid
swimmers
Order: Primates
Order: Hymenostomatida
Elongate oval cells with
cilia in the oral cavity
Family: Hominoidea
Family: Parameciidae
Cells rotate while swimming
and have oral grooves.
Genus: Homo
Genus: Paramecium
Pointed, cigar-shaped cells with
macronuclei and micronuclei
Species: caudatum
Cells cylindrical, long, and pointed
at one end
Species: sapiens
(a)
(b)

29. Concept Check:
Organisms in the same Family must also be in the same Class.
A. True
B. False

30. Assigning Specific Names
Binomial (scientific) nomenclature
Gives each microbe 2 names:
Genus - Capitalized
species - lowercase
Both italicized or underlined
Staphylococcus aureus (S. aureus)
Inspiration for names is extremely varied and often imaginative!

31. The Origin and Evolution of Microorganisms
Phylogeny: natural relatedness between groups of organisms
Evolution
All new species originate from pre-existing species
Closely related organism have similar features because they evolved from common ancestral forms
Evolution usually progresses toward greater complexity

32. Three Domains of Life Bacteria - true bacteria
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Bacteria true bacteria
Archaea odd bacteria that live in extreme environments, high salt, heat, etc.
Eukarya have a nucleus and organelles
Angiosperms
Chordates
Gymnosperms
Arthropods
Annelids
Echinoderms
Ferns
Mosses
Club
fungi
Mollusks
Seed plants
Yeasts
Nematodes
PLANTS
Kingdom
(Plantae)
FUNGI
Molds
Kingdom
(Myceteae)
Flatworms
ANIMALS
Kingdom
(Animalia)
Sponges
Red
algae
Slime
molds
Ciliates
First multicellular
organisms appeared
0.6 billion years ago.
Green
algae
Flagellates
Brown
algae
Amoebas
PROTISTS
Kingdom
(Protista)
Diatoms
Apicomplexans
EUKARYOTES
Dinoflagellates
Early eukaryotes
First eukaryotic
cells appeared
62 billion years ago.
PROKARYOTES
MONERANS
Kingdom
Monera
Archaea
Bacteria
5 kingdoms
First cells appeared
3–4 billion years ago.
2 cell types
Earliest cell

33. The Evolutionary Relationships Between Earth’s Inhabitants
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Kingdoms
Plantae
Animalia
Fungi
Protista
Domain Bacteria
Domain Archaea
Domain Eukarya
Prokaryotes
that live in
extreme salt
Prokaryotes
that live in
extreme heat
Chlamydias
Spirochetes
Gram-positive
bacteria
Endospore
producers
Gram-negative
bacteria
Methane
producers
Cyanobacteria
Eukaryotes
Ancestral Cell Line (first living cells)

34. Concept Check:
Organisms in the Domain Archaea have more DNA sequence similarity to
A. Escherichia coli which is in the Domain Bacteria
B. Humans which are in the Domain Eukarya
C. Archaea have no DNA sequence similarity to any other organism