Microbiology for the
Health Sciences:
Introduction, Overview and
History
Lecture 1 - Introduction
Topics
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Cowan
Scope of Microbiology
Importance of Microorganisms
Characteristics of Microorganisms
History of Microbiology
Taxonomy
Bauman
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Copyright The M cGraw-Hill Companies, Inc. Permission required for reproduction or display.
From the Modern Age of Microbiology
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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Table 1.3
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Bacteria appeared approximately 3.5 billion years ago.
Importance of Microbiology
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First bacteria
Photosynthesis and decomposition
Human use of microorganisms
Infectious diseases
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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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Fig. 1.1 Evolutionary timeline
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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.
Characteristics of Microorganisms
• Procaryotic – no nucleus and organelles
• Eucaryotic – nucleus and organelles
(mitochondria, etc.)
Fig. 1.4 Worldwide infectious disease statistics
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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.
Fig. 1.6 The six types of microorganisms
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Microorganisms vary in size - 1µm to 200 nm.
Some Microbiological History
• Ancient
• Chronology
• Progress
Fig. 1.7 The size
of things
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Really Ancient
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Communicable Disease?
• 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?
• 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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Microorganisms were first observed by Antonie van Leeuwenhoek,
using a primitive microscope.
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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• What Does Life Really Look Like?
Fig. 1.9 Leeuwenhoek’s microscope
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More Progress in Tools
– 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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• 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
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Spores and sterilization
Spores and sterilization
Spontaneous generation
Aseptic technique
Germ theory
• 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
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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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• 1600’s Francesco
Redi (Tuscany)
does rotting meat
experiment looking
for maggots
3 jars:
1. Covered
2. Uncovered
3. Meshed
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Do Microbes Cause Disease?
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.
• 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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• Scientists searched for answers to four
questions
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• Needham’s Experiments
– Scientists did not believe animals could arise
spontaneously, but did believe microbes could
– Is spontaneous generation of microbial life
possible?
– What causes fermentation?
– What causes disease?
– How can we prevent infection and disease?
– Needham’s experiments with beef gravy and
infusions of plant material reinforced this idea
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The development of an experimental system that answered
questions objectively was called “scientific method”.
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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Pasteur's application of the scientific method
Scientific Method
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Fig. 1.10 The pattern of deductive reasoning
Hypothesis
Experimentation
Results
Conclusion or theory
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Figure 1.14
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How about Fermentation?
Disease Knowledge Grows
– 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
• 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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Robert Koch verified the Germ theory (Koch’s postulates).
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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Koch was a busy man!
Koch’s Postulates
– 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
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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Aseptic Technique –
great idea!
Example Bacterial colonies on agar
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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Figure 1.16
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Ideas to Prevent Infection and Disease?
Summary - The Golden Age of Microbiology
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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Table 1.2
Taxonomy
Who worked
on what?
• A system for organizing, classifying & naming
living things.
• Primary concerns of taxonomy are
classification, nomenclature, and
identification.
Scientific
disciplines and
applications
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Figure 1.19
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Microbial Classification
Levels of Classification
– Carolus Linnaeus  developed taxonomic
system for naming plants and animals,
grouped similar organisms together
– Grouped Leeuwenhoek’s microorganisms
into six categories:
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Fungi
Protozoa
Algae
Bacteria
Archaea
Small multicellular animals
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Domain
Phylum or Division
Class
Order
Family
Genus
species
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Relationships:
Kingdom is inclusive… genus and species less inclusive
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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The new Domains idea –
(thanks Dr. Woese!)
The old 5 Kingdoms
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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
• 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
Nomenclature –
whats in a name?
•Developed by Dr. Woese
•rRNA sequence
information is basis
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Binomial (scientific) nomenclature
Genus – Bacillus, always capitalized
species - subtilis, lowercase
Both italicized or underlined
– Bacillus subtilis
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(B. subtilis)
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Identification
• Fungi
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• The process of discovering and
recording the traits (physical,
biochemical, genetic) of organisms,
thereby, placing them in a taxonomic
scheme.
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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What the heck is a Protozoan?
Example Fungus: (a) Penicillium chrysogenum, (b)
 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
Saccharomyces cerevisiae
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Figure 1.4
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So what about Algae?
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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
Unicellular or multicellular
Photosynthetic
Simple reproductive structures
Categorized on pigmentation, storage
products, composition of cell wall
• Bacteria
• Archaea
Diatoms
Spirogyra
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Parasitic worm in blood , immature stage
Phage
(bacterial
viruse)
infects a
bacterium
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Figure 1.8
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Figure 1.9
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Basic Chemical Reactions of Life?
– Biochemistry
Scope- continued…
• 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
• Additional topics about expanding
scope… the following slides..
– 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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Some quick Microbial Genetics stuff…
How does Genetics fit in?
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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
Microbial genetics
Molecular biology
Recombinant DNA technology
Gene therapy
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So what is Molecular Biology?
Bartonella sp. Unculterable?
– 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. : fastidious gram-
negative, facultative intracellular
parasite bacteria responsible for
bacillary angiomatosis, trench fever, cat
scratch disease, and endocarditis.
*Bartonella sp. see next slide
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Microorganisms and the Environment?
Recombinant DNA Technology
– Genes manipulation for practical applications
– Examples: human blood-clotting factor by E.
coli to aid hemophiliacs, human insuline
Gene Therapy
– Bioremediation
– Chemical recycling
– Oxygen
– Inserting missing gene or repairing defective
gene by inserting gene into host cells
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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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