Microbiology for the
Health Sciences:
Lecture 1 - Introduction
Cowan
Bauman
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Introduction, Overview and
History
Topics
– 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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From the Modern Age of Microbiology
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Table 1.3
Importance of Microbiology
•
•
•
•
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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2
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 - extract copper from ore, synthesize drugs and
enzymes, bioremediate contamination.
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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3
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
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Microorganisms vary in size - 1µm to 200 nm.
Fig. 1.7 The size
of things
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Some Microbiological History
• Ancient
• Chronology
• Progress
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Really Ancient
• Egypt >2800 BC: Beer, Wine
• Crete, Pakistan, Scotland 2800 BC:
Toilets and Sewers
• Rome, 315 AD: Public Lavatories w/
flowing water
• Aristotle, 384 AD: spontaneous
generation?
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5
Communicable Disease?
• Isolation of Individuals:
– Leper colonies (Mycobacterium leprae)
– Abandoning villages:
• Black Plague (Yersinia pestis) has killed 200
million!
• Small pox (Variola) killed 1/3 of Europe in
1348!
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Progress
• 1590 Hans & Zacharius Janssen:
Lense makers- first compound
microscope
• 1665 Robert Hooke- views and
describes fungi
• 1676 Anthony van Leeuwenhoekobserved first microscopic organism,
now blood cells and protists visable
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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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• What Does Life Really Look Like?
– Antoni van Leeuwenhoek (Dutch)
• Began making and using simple microscopes
• Often made a new microscope for each specimen
• Examined water and visualized tiny animals, fungi,
algae, and single-celled protozoa he called
animalcules
– By end of 19th century, called microorganisms
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More Progress in Tools
• 1883 Carl Zeiss and Ernst Abbe make
advancements in microscopy lenses
and techniques.
• 1931 Ernst Ruska- first EM scope
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History of Microbiology
•
•
•
•
Spores and sterilization
Spontaneous generation
Aseptic technique
Germ theory
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7
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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Spontaneous Generation?
• 1600’s Francesco
Redi (Tuscany)
does rotting meat
experiment looking
for maggots
3 jars:
1. Covered
2. Uncovered
3. Meshed
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8
Do Microbes Cause Disease?
• 1546 Girolamo Fracastoro wrote about
“contagion”
• 1835 Agostino Bassi de Lodi linked a
fungi with a silkworm disease– the first
recognized contageous agent of animal
disease!
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1861 -- Louis Pasteur uses swan necked-flasks to show
bacteria do not arise spontaneously.
He showed microbes caused fermentation and
spoilage, and disproved spontaneous generation.
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• Scientists searched for answers to four
questions
– Is spontaneous generation of microbial life
possible?
– What causes fermentation?
– What causes disease?
– How can we prevent infection and disease?
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• Needham’s Experiments
– Scientists did not believe animals could arise
spontaneously, but did believe microbes could
– Needham’s experiments with beef gravy and
infusions of plant material reinforced this idea
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Spallanzani’s Competing Experiments
– Concluded that
• Needham failed to heat vials sufficiently to kill all
microbes or had not sealed vials tightly enough
• Microorganisms exist in air and can contaminate
experiments
• Spontaneous generation of microorganisms does
not occur
– Critics said sealed vials did not allow enough
air for organisms to survive and that
prolonged heating destroyed “life force”
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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
•
•
•
•
Hypothesis
Experimentation
Results
Conclusion or theory
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Pasteur's application of the scientific method
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Figure 1.14
How about Fermentation?
– Spoiled wine
– air caused fermentation? living organisms
caused fermentation?
– Vintners  $$ for research to promote
production of alcohol but prevent spoilage
during fermentation
– This debate also linked to debate over
spontaneous generation
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Disease Knowledge Grows
• 1847 Ignaz Semmelweiss- Hungarian
physician- made his physicians wash
hands between patients (child-bed
fever)
• 1857 Louis Pasteur- (among many
things…) proposes germ theory
• 1867 Joseph Lister- Introduces
antiseptics in surgery (carbolic acid)
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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).
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Koch’s Postulates
1876 Robert Koch – cultivates Anthrax using
blood serum. Publishes postulates:
 Agent must be present in every case
 Agent must be isolated and cultured in vitro
 Disease must be produced when a pure culture is
inoculated into susceptible host
 Agent must be recoverable from infected host
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Koch was a busy man!
– Simple staining techniques
– First photomicrograph of bacteria
– First photomicrograph of bacteria in diseased
tissue
– Techniques for estimating CFU/ml
– Used steam to sterilize media
– Used Petri dishes
– Techniques to transfer bacteria
– Determined bacteria as distinct species
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Example Bacterial colonies on agar
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Figure 1.16
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Aseptic Technique –
great idea!
Joseph Lister first introduced
the technique to reduce
microbes in a medical setting
and prevent wound infections.
Based his work on Pasteur’s
research results.
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Ideas to Prevent Infection and Disease?
Semmelweis and handwashing
Lister’s antiseptic technique
Nightingale and nursing
Snow – infection control and epidemiology
Jenner’s vaccine – field of immunology
Ehrlich’s “magic bullets” – field of
chemotherapy
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Summary - The Golden Age of Microbiology
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Table 1.2
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Who worked
on what?
Scientific
disciplines and
applications
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Figure 1.19
Taxonomy
• A system for organizing, classifying & naming
living things.
• Primary concerns of taxonomy are
classification, nomenclature, and
identification.
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Microbial Classification
– Carolus Linnaeus  developed taxonomic
system for naming plants and animals,
grouped similar organisms together
– Grouped Leeuwenhoek’s microorganisms
into six categories:
•
•
•
•
•
•
Fungi
Protozoa
Algae
Bacteria
Archaea
Small multicellular animals
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Levels of Classification
•
•
•
•
•
•
•
Domain
Phylum or Division
Class
Order
Family
Genus
species
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Classification & Evolutionary Trends
• 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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Relationships:
Kingdom is inclusive… genus and species less inclusive
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The old 5 Kingdoms
•
•
•
•
•
Monerans
Fungi
Protists
Plants
Animals
The five-kingdom system was standard
until molecular biology techniques to
developed the Domain system
Traditional Whittaker
system of classification
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The new Domains idea –
(thanks Dr. Woese!)
• Developed after the five-kingdom
system
• Eubacteria -true bacteria, peptidoglycan
• Archaea – (Dr. Carl Woese) odd
bacteria that live in extreme
environments, high salt, heat, etc
• Eukarya- have a nucleus, & organelles
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The Domain system
•Developed by Dr. Woese
•rRNA sequence
information is basis
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Nomenclature –
whats in a name?
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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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• Fungi
– Eukaryotic (have membrane-bound nucleus)
– Heterotrophic
– Cell walls
– Includes
• Molds – multicellular; long filaments; sexual and
asexual spores
• Yeasts – unicellular; asexual budding; some sexual
spores
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Example Fungus: (a) Penicillium chrysogenum, (b)
Saccharomyces cerevisiae
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Figure 1.4
What the heck is a Protozoan?
 Single-celled eukaryotes
 Similar to animals in nutrient needs and cellular structure
 Live freely in water; some in animal hosts
 Asexual (most) and sexual repro
 Most motile via:
• Pseudopods
• Cilia
• Flagella
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So what about Algae?
– Unicellular or multicellular
– Photosynthetic
– Simple reproductive structures
– Categorized on pigmentation, storage
products, composition of cell wall
Diatoms
Spirogyra
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Bacteria and Archaea
– Unicellular, no nuclei
– smaller than eukaryotes
– Found everywhere there is sufficient moisture;
some isolated from extreme environments
– Reproduce asexually
– Two kinds
• Bacteria
• Archaea
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Parasitic worm in blood , immature stage
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Figure 1.8
Phage
(bacterial
viruse)
infects a
bacterium
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Figure 1.9
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Scope- continued…
• Additional topics about expanding
scope… the following slides..
61
Basic Chemical Reactions of Life?
– Biochemistry
• Began with Pasteur’s work on fermentation and
Buchner’s discovery of enzymes in yeast extract
• Kluyver and van Niel – microbes used as model
systems for biochemical reactions
• Practical applications
– Design of herbicides and pesticides
– Diagnosis of illnesses and monitoring of patients’
responses to treatment
– Treatment of metabolic diseases
– Drug design
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How does Genetics fit in?
– Microbial genetics
– Molecular biology
– Recombinant DNA technology
– Gene therapy
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Some quick Microbial Genetics stuff…
Milestones:
 Avery, MacLeod, and McCarty showed genes are
contained in DNA
 Beadle and Tatum established a gene’s activity 
related to protein function
 Translation of genetic information into protein
explained
 Rates and mechanisms of genetic mutation
investigated
 Control of genetic expression by cells described
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So what is Molecular Biology?
– Explanation of cell function at the molecular level
– Pauling proposed that gene sequences could
• Provide understanding of evolutionary relationships and
processes
• Establish taxonomic categories to reflect these relationships
• Identify existence of microbes that have never been cultured
– Woese defined cells belong to bacteria, archaea, or eukaryotes
– Cat scratch disease caused by unculturable organism*
*Bartonella sp. see next slide
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Bartonella sp. Unculterable?
Bartonella sp. : fastidious gram-
negative, facultative intracellular
parasite bacteria responsible for
bacillary angiomatosis, trench fever, cat
scratch disease, and endocarditis.
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Recombinant DNA Technology
– Genes manipulation for practical applications
– Examples: human blood-clotting factor by E.
coli to aid hemophiliacs, human insuline
Gene Therapy
– Inserting missing gene or repairing defective
gene by inserting gene into host cells
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Microorganisms and the Environment?
– Bioremediation
– Chemical recycling
– Oxygen
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Immunological Defense Against Disease ?
– Serology
• study of blood serum
• Von Behring and Kitasato – blood chemicals and
cells that fight infection
– Immunology
• The study of the body’s defense against specific
pathogens
– Chemotherapy
• Domagk  sulfa drugs
• Bacteriophages  Georgia, USSR
• Fleming  penicillin
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