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PowerPoint to accompany
Microbiology:
A Systems Approach
Cowan/Talaro
Chapter 1
The Main Themes of
Microbiology
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chapter 1
Topics
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Scope of Microbiology
Importance of Microorganisms
Characteristics of Microorganisms
History of Microbiology
Taxonomy
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Scope of Microbiology
• Immunology
• Public health microbiology &
epidemiology
• Food, dairy and aquatic microbiology
• Agricultural microbiology
• Biotechnology
• Genetic engineering & recombinant
DNA technology
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Importance of Microbiology
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First bacteria
Photosynthesis and decomposition
Human use of microorganisms
Infectious diseases
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Bacteria appeared approximately 3.5 billion years ago.
Fig. 1.1 Evolutionary timeline
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Microbes are involved in photosynthesis - account for >50% of
the earth’s oxygen. Decomposition – nutrient recycling.
Fig. 1.2 Microbial habitats
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Microbes are used to extract copper from ore, synthesize drugs
and enzymes, and bioremediate contaminated water.
Fig. 1.3 Microbes at work
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The most common infectious diseases worldwide.
Fig. 1.4 Worldwide infectious disease statistics
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Characteristics of Microorganisms
• Procaryotic – no nucleus and organelles
• Eucaryotic – nucleus and organelles
(mitochondria, etc.)
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There is a difference between the cell structure of a procaryote
and eucaryote. Viruses are neither but are considered particles.
Fig. 1.5 Cell structure
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There are six main types of microorganisms: 1.) bacterium, 2.)
Fungus, 3.) Algae, 4.) Virus, 5.) Protozoan, 6.) Helminth.
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Fig. 1.6 The six types of microorganisms
Microorganisms vary in size - 1µm to 200 nm.
Fig. 1.7 The size
of things
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Microorganisms were first observed by Antonie van Leeuwenhoek,
using a primitive microscope.
Fig. 1.9 Leeuwenhoek’s microscope
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The development of an experimental system that answered
questions objectively was called “scientific method”.
Fig. 1.10 The pattern of deductive reasoning
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Scientific Method
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Hypothesis
Experimentation
Results
Conclusion or theory
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History of Microbiology
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Spores and sterilization
Spontaneous generation
Aseptic technique
Germ theory
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Spores and sterilization
• Some microbes in dust and air were
resistant to high heat.
• Spores were later identified.
• The term “sterile” was introduced which
meant completely eliminating all life
forms from objects or materials.
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Spontaneous generation
Early belief that some forms of life could
arise from vital forces present in
nonliving or decomposing matter. (flies
from manure, etc)
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Jan Baptista van Helmont’s
recipe for mice
• Place a dirty shirt or some
rags in an open pot or
barrel containing a few
grains of wheat or some
wheat bran, and in 21
days, mice will appear.
• There will be adult males
and females present, and
they will be capable of
mating and reproducing
more mice.
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Recipe for bees
• Kill a young bull,
and bury it in an
upright position so
that its horns
protrude from the
ground.
• After a month, a
swarm of bees will
fly out of the corpse.
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Louis Pasteur showed microbes caused fermentation &
spoilage, and disproved spontaneous generation.
Fig. 1.11 Louis Pasteur
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pasteur’s Experiment
Microbes
being
destroyed
Vigorous heat
is applied.
(d)
Broth free of
live cells (sterile)
Neck on second
sterile flask
is broken;
growth occurs.
Neck intact; airborne
microbes are
trapped at base,
and broth is sterile.
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.
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Robert Koch verified the Germ theory (Koch’s postulates).
Fig. 1.12 Robert Koch
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Semmelwiess and Hand
Washing
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Aseptic technique
Joseph Lister first introduced the
technique in order to reduce microbes
in a medical setting and prevent wound
infections.
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Taxonomy
• A system for organizing, classifying & naming
living things.
• Primary concerns of taxonomy are
classification, nomenclature, and
identification.
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Levels of Classification
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Domain
Kingdom
Phylum or Division
Class
Order
Family
Genus
species
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Notice how inclusive a kingdom can be, and how less inclusive a
genus and species can be.
Fig. 1.13 Sample taxonomy
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Domains
• Developed after the five-kingdom
system
• Eubacteria -true bacteria, peptidoglycan
• Archaea –odd bacteria that live in
extreme environments, high salt, heat,
etc
• Eukarya- have a nucleus, & organelles
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The Domain system was developed by Dr. Woese. The basis of
the Domain system is the rRNA sequence information.
Fig. 1.15 Woese system
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Subdivisions or Kingdoms
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Monerans
Fungi
Protists
Plants
Animals
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The five-kingdom system became the standard until molecular
biology techniques were used to develop the Domain system.
Fig. 1.14 Traditional Whittaker system of classification
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Evolution
• Classification schemes allow for a
universal tree of life “phylogenetic tree”.
• Living things change gradually over
millions of years
• Changes favoring survival are retained
& less beneficial changes are lost.
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Nomenclature
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Binomial (scientific) nomenclature
Genus – Bacillus, always capitalized
species - subtilis, lowercase
Both italicized or underlined
– Bacillus subtilis
(B. subtilis)
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Identification
• The process of discovering and
recording the traits (physical,
biochemical, genetic) of organisms,
thereby, placing them in a taxonomic
scheme.
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