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2013/2/18
Chapter 1
The Microbial
World and You
© 2013 Pearson Education, Inc.
Copyright © 2013 Pearson Education, Inc.
Lectures prepared by Christine L. Case
Lectures prepared by Christine L. Case
© 2013 Pearson Education, Inc.
Microbes in Our Lives
Microbes in Our Lives
 Microorganisms are organisms that are too small to
be seen with the unaided eye
 Germ refers to a rapidly growing cell
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© 2013 Pearson Education, Inc.
Designer Jeans: Made by Microbes?
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A few are pathogenic (disease-causing)
Decompose organic waste
Are producers in the ecosystem by photosynthesis
Produce industrial chemicals such as ethanol
and acetone
 Produce fermented foods such as vinegar, cheese,
and bread
 Produce products used in manufacturing
(e.g., cellulase) and disease treatment (e.g., insulin)
Applications of Microbiology 1.1 Indigo-producing E. coli bacteria.
Stone-washing: Trichoderma
Cotton: Gluconacetobacter
Debleaching: mushroom peroxidase
Indigo: E. coli
Pl ti b
Plastic:
bacterial
t i l polyhydroxyalkanoate
l h d
lk
t
Indigo-producing E. coli bacteria.
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Applications of Microbiology 1.1 E. coli bacteria produce indigo from tryptophan.
Microbes in Our Lives
 Knowledge of microorganisms
 Allows humans to
 Prevent food spoilage
 Prevent disease occurrence
 Led to aseptic techniques to prevent contamination
in medicine and in microbiology laboratories
E. coli bacteria
produce indigo
from tryptophan.
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© 2013 Pearson Education, Inc.
Naming and Classifying Microorganisms
Scientific Names
 Linnaeus established the system of scientific
nomenclature
 Each organism has two names: the genus and
specific epithet
 Are italicized or underlined
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Escherichia coli
Staphylococcus aureus
 Honors the discoverer, Theodor Escherich
 Describes the bacterium’s habitat—the large
intestine, or colon
 Describes the clustered (staphylo-) spherical (cocci)
cells
 Describes the gold-colored (aureus) colonies
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 The genus is capitalized; the specific epithet is lowercase
 Are “Latinized” and used worldwide
 May be descriptive or honor a scientist
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Scientific Names
Scientific Names
 After the first use, scientific names may be
abbreviated with the first letter of the genus and the
specific epithet:

 Escherichia coli and Staphylococcus aureus are found in
the human body
 E. coli is found in the large intestine, and S. aureus is on
skin
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Which is a correct scientific name?
a.
b.
c.
d.
Baker’s yeast
Saccharomyces cerevisiae
Saccharomyces cerevisiae
S. cerevisiae
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Figure 1.1 Types of microorganisms.
Types of Microorganisms
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Bacteria
Archaea
Fungi
Protozoa
Al
Algae
Viruses
Multicellular animal parasites
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Sporangia
Bacteria
Prey
Pseudopods
CD4+ T cell
HIVs
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Figure 1.1a Types of microorganisms.
Bacteria
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Prokaryotes
Peptidoglycan cell walls
Binary fission
For energy, use organic chemicals, inorganic
chemicals or photosynthesis
chemicals,
Bacteria
(a) The rod-shaped bacterium Haemophilus influenzae,
one of the bacterial causes of pneumonia.
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Figure 4.5b Star-shaped and rectangular prokaryotes.
Archaea
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Prokaryotic
Lack peptidoglycan
Live in extreme environments
Include:
 Methanogens
M th
 Extreme halophiles
 Extreme thermophiles
Rectangular bacteria
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Figure 1.1b Types of microorganisms.
Fungi
Sporangia
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Eukaryotes
Chitin cell walls
Use organic chemicals for energy
Molds and mushrooms are multicellular,
consisting of masses of mycelia
mycelia, which are
composed of filaments called hyphae
 Yeasts are unicellular
(b) Mucor, a common bread mold, is a type of fungus.
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Figure 1.1c Types of microorganisms.
Protozoa
 Eukaryotes
 Absorb or ingest organic chemicals
 May be motile via pseudopods, cilia, or flagella
Prey
Pseudopods
(c) An ameba, a protozoan, approaching a food particle.
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Figure 1.1d Types of microorganisms.
Algae
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Eukaryotes
Cellulose cell walls
Use photosynthesis for energy
Produce molecular oxygen and organic compounds
(d) The pond alga Volvox.
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Figure 1.1e Types of microorganisms.
Viruses
CD4+ T cell
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HIVs
Acellular
Consist of DNA or RNA core
Core is surrounded by a protein coat
Coat may be enclosed in a lipid envelope
A replicated
Are
li t d only
l when
h th
they are iin a liliving
i h
hostt cellll
(e) Several human immunodeficiency viruses (HIVs), the
causative agent of AIDS, budding from a CD4+ T cell.
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Figure 1.6 Parasitology: the study of protozoa and parasitic worms.
Multicellular Animal Parasites
 Eukaryotes
 Multicellular animals
 Parasitic flatworms and roundworms are called
helminths
 Microscopic stages in life cycles
Rod of
Asclepius,
symbol of the
medical
profession.
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A parasitic guinea worm (Dracunculus medinensis)
is removed from the subcutaneous tissue of a patient
by winding it onto a stick. This procedure may have
been used for the design of the symbol in part (a).
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Figure 10.1 The Three-Domain System.
Classification of Microorganisms
Eukarya
 Three domains
 Bacteria
 Archaea
 Eukarya
 Protists
 Fungi
 Plants
 Animals
Bacteria
Animals
Fungi
Origin of mitochondria
Origin of chloroplasts
Amebae
Mitochondria
Slime molds
Cyanobacteria
Proteobacteria
Chloroplasts
Archaea
Ciliates
Plants
Extreme
halophiles
Green
algae
Methanogens
Dinoflagellates
Diatoms
Hyperthermophiles
Gram-positive
bacteria
Euglenozoa
Giardia
Thermotoga
Horizontal gene transfer
occurred within the
community of early cells.
Mitochondrion degenerates
Nucleoplasm grows larger
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A Brief History of Microbiology
The First Observations
 Ancestors of bacteria were the first life on Earth
 The first microbes were observed in 1673
 1665: Robert Hooke reported that living things are
composed of little boxes, or cells
 1858: Rudolf Virchow said cells arise from
preexisting cells
 Cell theory: All living things are composed of cells
and come from preexisting cells
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Figure 1.2b Anton van Leeuwenhoek’s microscopic observations.
The First Observations
Lens
Location of specimen
on pin
 1673–1723: Anton van Leeuwenhoek described live
microorganisms
Specimen-positioning
screw
Focusing control
Stage-positioning screw
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Microscope replica
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The Debate over Spontaneous
Generation
 Spontaneous generation: the hypothesis that living
organisms arise from nonliving matter;
a “vital force” forms life
 Biogenesis: the hypothesis that living organisms
arise from preexisting life
Evidence Pro and Con
 1668: Francesco Redi filled 6 jars with
decaying meat
Conditions
Results
Three jars covered with fine net
No maggots
Three open jars
Maggots appeared
From where did the maggots come?
What was the purpose of the sealed jars?
Spontaneous generation or biogenesis?
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Evidence Pro and Con
Evidence Pro and Con
 1745: John Needham put boiled nutrient broth into
covered flasks
 1765: Lazzaro Spallanzani boiled nutrient solutions
in flasks
Conditions
Results
Nutrient broth heated, then placed Microbial growth
in sealed flask
Nutrient broth placed in flask,
flask
heated, then sealed
No microbial growth
From where did the microbes come?
Spontaneous generation or biogenesis?
Spontaneous generation or biogenesis?
Conditions
Results
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Evidence Pro and Con
The Theory of Biogenesis
 1861: Louis Pasteur demonstrated that
microorganisms are present in the air
 Pasteur’s S-shaped flask kept microbes out
but let air in
Conditions
Results
Nutrient broth placed in flask,
flask
heated, NOT sealed
Microbial growth
Nutrient broth placed in flask,
heated, then sealed
No microbial growth
Spontaneous generation or biogenesis?
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Figure 1.3 Disproving the Theory of Spontaneous Generation.
Pasteur first poured
beef broth into a
long-necked flask.
Next he heated the neck
of the flask and bent it
into an S-shape; then he
boiled the broth for
several minutes.
Microorganisms did not
appear in the cooled solution,
even after long periods.
Bend prevented microbes
from entering the flask.
The Golden Age of Microbiology
 1857–1914
 Beginning with Pasteur’s work, discoveries included
the relationship between microbes and disease,
immunity, and antimicrobial drugs
Microorganisms were
present in the broth.
Microorganisms were not
present in the broth after
boiling.
Microorganisms were
not present even after
long periods.
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Fermentation and Pasteurization
Fermentation and Pasteurization
 Pasteur showed that microbes are responsible for
fermentation
 Fermentation is the conversion of sugar to alcohol
to make beer and wine
 Microbial growth is also responsible for spoilage of
food
 Bacteria that use alcohol and produce acetic acid
spoil wine by turning it to vinegar (acetic acid)
 Pasteur demonstrated that these spoilage bacteria
could be killed by heat that was not hot enough to
evaporate the alcohol in wine
 Pasteurization is the application of a high heat for a
short time
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The Germ Theory of Disease
 1835: Agostino Bassi showed that a silkworm
disease was caused by a fungus
 1865: Pasteur believed that another silkworm
disease was caused by a protozoan
 1840s: Ignaz Semmelweis advocated handwashing
to prevent transmission of puerperal fever from one
obstetrical patient to another
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The Germ Theory of Disease
 1860s: Applying Pasteur’s work showing microbes
are in the air, can spoil food, and cause animal
diseases, Joseph Lister used a chemical disinfectant
to prevent surgical wound infections
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The Germ Theory of Disease
 1876: Robert Koch proved that a bacterium
causes anthrax and provided the experimental
steps, Koch’s postulates, to prove that a specific
microbe causes a specific disease
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Vaccination
The Birth of Modern Chemotherapy
 1796: Edward Jenner inoculated a person with
cowpox virus, who was then protected from smallpox
 Vaccination is derived from vacca, for cow
 The protection is called immunity
 Treatment with chemicals is chemotherapy
 Chemotherapeutic agents used to treat infectious
disease can be synthetic drugs or antibiotics
 Antibiotics are chemicals produced by bacteria and
fungi that inhibit or kill other microbes
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The First Synthetic Drugs
A Fortunate Accident—Antibiotics
 Quinine from tree bark was long used to treat
malaria
 Paul Ehrlich speculated about a “magic bullet” that
could destroy a pathogen without harming the host
 1910: Ehrlich developed a synthetic arsenic drug
drug,
salvarsan, to treat syphilis
 1930s: sulfonamides were synthesized
 1928: Alexander Fleming discovered the first
antibiotic
 Fleming observed that Penicillium fungus made an
antibiotic, penicillin, that killed S. aureus
 1940s: Penicillin was tested clinically and mass
produced
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Figure 1.5 The discovery of penicillin.
Modern Developments in Microbiology
Normal
bacterial
colony
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Bacteriology is the study of bacteria
Mycology is the study of fungi
Virology is the study of viruses
Parasitology is the study of protozoa and parasitic
worms
Area of
inhibition of
bacterial
growth
Penicillium
colony
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Modern Developments in Microbiology
 Immunology is the study of immunity
 Vaccines and interferons are being investigated to prevent
and cure viral diseases
 The use of immunology to identify some bacteria
according
g to serotypes
yp was p
proposed
p
by
y Rebecca
Lancefield in 1933
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Recombinant DNA Technology
Recombinant DNA Technology
 Microbial genetics: the study of how microbes
inherit traits
 Molecular biology: the study of how DNA directs
protein synthesis
 Genomics: the study of an organism
organism’ss genes; has
provided new tools for classifying microorganisms
 Recombinant DNA: DNA made from two different
sources
 1941: George Beadle and Edward Tatum showed
that genes encode a cell’s enzymes
 1944: Oswald Avery, Colin MacLeod, and Maclyn
McCarty showed that DNA is the hereditary material
 1961: François Jacob and Jacques Monod
discovered the role of mRNA in protein synthesis
 In the 1960s, Paul Berg inserted animal DNA into bacterial
DNA, and the bacteria produced an animal protein
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Nobel Prizes for Microbiology Research
Microbial Ecology
 * The first Nobel Prize in Physiology or Medicine
1901*
1902
1905
1908
1945
1952
1969
1997
2005
2008
2008
von Bering
Ross
Koch
Metchnikoff
Fleming,
g Chain, Florey
y
Waksman
Delbrück, Hershey, Luria
Prusiner
Marshall & Warren
zur Hausen
Barré-Sinoussi
& Montagnier
Diphtheria antitoxin
Malaria transmission
TB bacterium
Phagocytes
Penicillin
Streptomycin
Viral replication
Prions
H. pylori & ulcers
HPV & cancer
 Bacteria recycle carbon, nutrients, sulfur, and
phosphorus that can be used by plants and animals
HIV
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Figure 27.10 Composting municipal wastes.
Bioremediation
 Bacteria degrade organic matter in sewage
 Bacteria degrade or detoxify pollutants such as oil
and mercury
Solid municipal wastes being turned by a specially designed machine
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Figure 11.15a Bacillus.
Biological Insecticides
 Microbes that are pathogenic to insects are
alternatives to chemical pesticides in preventing
insect damage to agricultural crops and disease
transmission
 Bacillus thuringiensis
g
infections are fatal in many
y
insects but harmless to other animals, including
humans, and to plants
Insert Fig 11.15a
11 15a
(a) Bacillus thuringiensis. The diamond-shaped crystals
shown next to the endospore are toxic to insects that
ingest them. This electron micrograph was made
using the technique of shadow casting described on page 62.
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Figure 28.8 Making cheddar cheese.
Biotechnology
 Biotechnology, the use of microbes to produce
foods and chemicals, is centuries old
The milk has been coagulated by the
action of rennin (forming curd) and is
inoculated
bacteria
i
l t d with
ith ripening
i
i
b t i for
f
flavor and acidity. Here the workers are
cutting the curd into slabs.
The curd is chopped into small cubes to
facilitate efficient draining of whey.
The curd is milled to allow even more
drainage of whey and is compressed into
blocks for extended ripening. The longer the
ripening, the more acidic (sharper) the cheese.
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Applications of Microbiology, unnumbered figure, page 808.
Biotechnology
Xanthan
 Recombinant DNA technology, a new technique
for biotechnology, enables bacteria and fungi to
produce a variety of proteins, including vaccines and
enzymes
 Missing or defective genes in human cells can be replaced
in gene therapy
 Genetically modified bacteria are used to protect crops
from insects and from freezing
Xanthomonas campestris producing gooey xanthan.
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Figure 1.7 Several types of bacteria found as part of the normal microbiota on the surface of the human tongue.
Normal Microbiota
 Bacteria were once classified as plants, giving rise to
use of the term flora for microbes
 This term has been replaced by microbiota
 Microbes normally present in and on the human
body are called normal microbiota
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Normal Microbiota
Biofilms
 Normal microbiota prevent growth of pathogens
 Normal microbiota produce growth factors, such as
folic acid and vitamin K
 Resistance is the ability of the body to ward off
disease
 Resistance factors include skin, stomach acid, and
antimicrobial chemicals
 Microbes attach to solid surfaces and grow into
masses
 They will grow on rocks, pipes, teeth, and medical
implants
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Figure 1.8 Biofilm on a catheter.
Staphylococcus
Infectious Diseases
 When a pathogen overcomes the host’s resistance,
disease results
 Emerging infectious diseases (EIDs): new
diseases and diseases increasing in incidence
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Figure 13.3b Morphology of an enveloped helical virus.
Avian Influenza A
 Influenza A virus
 Primarily in waterfowl and poultry
 Sustained human-to-human transmission has not
occurred yet
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MRSA
West Nile Encephalitis
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 Caused by West Nile virus
 First diagnosed in the West Nile region of Uganda
in 1937
 Appeared in New York City in 1999
 In nonmigratory birds in 47 states
Methicillin-resistant Staphylococcus aureus
1950s: Penicillin resistance developed
1980s: Methicillin resistance
1990s: MRSA resistance to vancomycin reported
 VISA
VISA: vancomycin-intermediate-resistant
i i t
di t
i t t S.
S aureus
 VRSA: vancomycin-resistant S. aureus
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Disease in Focus 22.2 Types of Arboviral Encephalitis, unnumbered figure.
Bovine Spongiform Encephalopathy
 Caused by a prion
 Also causes Creutzfeldt-Jakob disease (CJD)
 New variant CJD in humans is related to cattle that
have been fed sheep offal for protein
Culex mosquito engorged with human blood.
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Figure 22.18b Spongiform encephalopathies.
Escherichia coli O157:H7
 Toxin-producing strain of E. coli
 First seen in 1982
 Leading cause of diarrhea worldwide
Insert Fig 22.18b
22 18b
Holes
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Figure 25.12 Pedestal formation by Enterhemorrhagic E. coli (EHEC) O157:H7.
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Ebola Hemorrhagic Fever
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
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Ebola virus
Causes fever, hemorrhaging, and blood clotting
First identified near Ebola River, Congo
Outbreaks every few years
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Figure 23.22 Ebola hemorrhagic virus.
Cryptosporidiosis
 Cryptosporidium protozoa
 First reported in 1976
 Causes 30% of diarrheal illness in developing
countries
 In the United States
States, transmitted via water
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Figure 25.18 Cryptosporidiosis.
Intestinal
mucosa
Acquired immunodeficiency syndrome
(AIDS)
Oocyst
 Caused by human immunodeficiency virus (HIV)
 First identified in 1981
 Worldwide epidemic infecting 33 million people;
7500 new infections every day
 Sexually transmitted infection affecting males and
females
 HIV/AIDS in the United States: 26% are female, and
49% are African American
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