Microbiology: The Human Experience PowerPoint Lecture ch 1

Chapter
JOHN W. FOSTER  ZARRINTAJ ALIABADI  JOAN L. SLONCZEWSKI
MICRO
BIOLOGY
THE HUMAN EXPERIENCE
Microbes Shape Our History
1

© 2016 W. W. Norton Co., Inc.
Chapter Objectives
• Describe the discovery of microbes related to
human health, including the tools of microscopy
and medical statistics.
• Explain Koch’s postulates for showing that a
microbe causes disease.
• Describe how environmental microbes are
essential for human life.
2
Microbes Shape Our History

Half a Lung Is Better than None – 1
Scenario
Debi was an ordinary
teenager attending an
affluent American public high
school when she contracted
tuberculosis (TB). She did not
know the person who
infected her. Infection
requires inhalation of the
causative bacteria.
3

Signs and Symptoms
Debi coughed all the time,
felt tired, and was losing
weight.
Her coughing brought up
blood.
An X-ray revealed the signs of infection in her lung,
including a large hole eaten away by the bacteria.
4

Diagnosis
From Debi’s sputum sample,
a DNA sequence was
amplified by PCR
(polymerase chain reaction).
The DNA sequence revealed
Mycobacterium tuberculosis,
the cause of TB.
5

Treatment
Doctors prescribed
isoniazid and rifampin,
antibiotics that kill most
strains of M. tuberculosis.
But Debi’s TB strain proved
resistant to nearly all known drugs (MDR-TB).
Because drugs failed to eliminate the MDR strain,
surgeons removed nearly half of her right lung to help
the antibiotics overcome the infection.
6

Treatment
Debi recovered and
returned to high school.
She would have to continue
taking antibiotics for years
afterward.
All the teachers and students in Debi’s school were
screened, and over 200 were found to have been
infected by a student with tuberculosis misdiagnosed
for two years. All required treatment to prevent
disease.
7

Section Objectives
• Describe how we define a microbe, and explain
why the definition is a challenge.
• Describe the three major domains of life: Archaea,
Bacteria, and Eukarya. Explain what the three
domains have in common and how they differ.
• Define viruses, and explain how they relate to
living cells.
8
1.1 From Germ to Genome: What is a Microbe? – 1

Where did life come from?
• Life on Earth began early in our planet’s history
with microscopic organisms.
• Microbial life has shaped our atmosphere, our
geology, and the energy cycles of all ecosystems.
• Early microbes eventually evolved into multicellular
plants and animals, including humans.
9

Microbes
• generate the air we breathe
oxygen
carbon dioxide
nitrogen gas
• fix nitrogen into forms used by plants
• make essential vitamins
vitamin B12
vitamin K
• produce food webs
10

Microbes
• Human body contains 10x as many microbes as
human cells.
• Human relationship with microbes
• food production
• food preservation
• mining for precious minerals
• biotechnology tools
• Small, but critical proportion are pathogens.
• disease causing
• remain the principal cause of human mortality
11

A Microbe Is a Microscopic Organism
Simple definition of a microbe leaves us with
contradictions:
• Some protists and algae can be seen with the
naked eye.
• amebas
• Pelomyxa
12

Simple definition of a microbe leaves us with
contradictions:
• Some form complex multicellular assemblages.
• mycelia (multicellular filaments)
• biofilms
• Some complex multicellular organisms require a
microscope for us to see but are not considered
microbes.
• mites
• roundworms
13

Classified as members of a species, according
to a shared set of genes and traits
Scientific name of the species consists of a
capitalized genus name and a lowercase
species name, which are both italicized.
• Staphylococcus epidermidis
• Escherichia coli
14

• The more closely related organisms are, the more
recently they diverged from a common ancestor.
• Degree of relatedness is determined by comparing
the DNA sequences of their genomes, the total
DNA sequence content of an organism.
15

Major trait that distinguishes different types of
microbes is the possession or absence of a
membrane-enclosed nucleus.
• Prokaryotes
• lack a nuclear membrane
• include bacteria and archaea
• Eukaryotes
• possess a nuclear membrane (nucleus)
• include fungi, protozoa, and algae
16

17

Bacteria
• prokaryotic
• 0.2–20 µm
• may grow as single cells, filaments,
communities
Archaea
• prokaryotic
• genetically distinct from bacteria
• “extremophiles”
• nonpathenogenic
18

Protozoa
• eukaryotic
• motile, single-celled organisms
• may be free-living or parasitic
Algae
• eukaryotic
• contain chloroplasts and conduct
photosynthesis
• base of the food web
19

Fungi
• eukaryotic
• nonmotile
• grow by absorbing nutrients from surroundings
• grow as single cells or as filaments
• can cause disease
Viruses
• noncellular
• genetic material (DNA or RNA) that can take over
the metabolism of a cell to generate more viruses
• can cause disease
• also used as biotechnology tools
20

Section Objectives
• Explain how microbial diseases have changed
human history.
• Describe how microbes participate in human
cultural practices such as production of food and
drink.
21
1.2 Microbes Shape Human History – 1

Have microbes changed the course of
human history?
devastation of human populations by microbial
diseases
• tuberculosis
• leprosy
• smallpox
• bubonic plague
22

Microscopes Reveal the Microbial World
Robert Hooke built
the first compound
microscope.
23

Microscopes Reveal the Microbial World
Anton van Leeuwenhoek
observed bacteria with
a single lens.
24

Spontaneous generation
the theory that living microbes
can arise spontaneously without
parental organisms.
• Spallanzani’s sealed flask experiment
• opponents argued that since the flask was sealed,
oxygen was not present and microbes could not grow.
• Pasteur’s “swan neck” flask allowed oxygen to enter, but
kept the boiled contents free of microbes.
25

Have microbes changed the course of
human history?
The Origin of Life
• If all life on Earth shares descent from a microbial
ancestor, how did the first microbes arise?
• Earliest fossil evidence of cells appears in sedimentary
rock that formed over 2 billion years ago.
• Living cell components may have formed from
spontaneous reactions sparked by UV absorption or
electrical discharge.
• Stanley Miller’s experiment
• origins of life remain a mystery
26

Section Objectives
• Define the germ theory of disease.
• Explain how Florence Nightingale first drew a
statistical correlation between infectious diseases
and human mortality.
• Explain how Koch’s postulates can show that a
specific kind of microbe causes a disease. Explain
the problems in interpreting Koch’s postulates in
practice.
27
1.3 Medical Microbiology and Immunology – 1

Linking Infectious Disease with Mortality
• Germ Theory of Disease
• Specific diseases are caused by specific kinds
of microbes.
• Disease is common in
overcrowded areas like
cities and during warfare.
• Florence Nightingale
demonstrated the
significance of mortality
due to disease.
28

29

Epidemiology
• Statistical analysis continues to serve as a
crucial tool for determining causes of disease.
• Public Health is now a major field of service.
• Centers for Disease Control and Prevention(CDC)
• World Health Organization (WHO)
30

The CDC tracks epidemics of seasonal influenza
and tries to predict which strains will require
vaccination in a given year.
31

Case History 1.1 Sickened by Dead Cattle
In 2000, on a farm in
North Dakota, 67-year-old
Caleb helped bury 5 cows
that had died of anthrax.
Wearing heavy leather gloves, Caleb placed chains
around the heads and hooves of the carcasses and
moved them to the burial site. Four days later, he
noticed a small lump on his left cheek. Over two days,
the lump enlarged and a lesion opened.
32

Caleb sought medical attention. The physician
reported a firm, superficial nodule surrounded by a
purple ring, with an overlying black eschar (piece of
dead tissue sloughed from the skin).
The physician prescribed
ciprofloxacin, the
standard antibiotic for
cutaneous anthrax.
33

Testing the patient’s serum with a bacterial antigen
revealed the presence of antibodies, confirming the
diagnosis of anthrax.
The ciprofloxacin was
continued and the
patient slowly improved
over several weeks.
34

Growth of Microbes in Pure Culture
Diagnosis for a patient requires more direct evidence
that a given microbe causes a given disease.
Robert Koch developed the first scientific method for
establishing the microbial cause of a disease.
35

36

Koch’s postulates link a pathogen with a
disease.
1. The microbe is found in all cases of the disease, but
absent from healthy individuals.
2. The microbe is isolated from the diseased host and grown
in pure culture.
3. When the microbe is introduced into a healthy, susceptible
host (or animal model), the same disease occurs.
4. The same strain of microbe is obtained from the newly
diseased host. When cultured, the strain shows the same
characteristics as before.
37

38

Individual diseases and pathogens may
confound one or more of the criteria:
• M. tuberculosis is now known to cause
symptoms in only 10% of people infected.
• HIV is difficult to detect in early stages and
is an exclusively human pathogen.
Experimenting with humans would be
unethical.
39

Immunization Prevents Disease
By 1000 BCE in India and China, it was known
that individuals could be made immune to
smallpox by transferring secretions from a
diseased individual to healthy ones.
In the 18th century, the incidence of smallpox
was decreased by deliberately inoculating
children with material from smallpox pustules.
40

The practice of smallpox inoculation was
introduced from Turkey to other parts of
Europe by Lady Mary Wortley Montagu, a
smallpox survivor and the wife of the British
Ambassador.
She brought the practice
back to England, where it
became widespread.
41

Preventative inoculation with smallpox was
dangerous, as some infected individuals still
contracted serious disease and were contagious.
Dr. Edward Jenner
deliberately infected patients
with matter drawn from
cowpox lesions. The process
of cowpox inoculation was
called vaccination.
42

Louis Pasteur was the first to show that
infecting with attenuated (weakened) strains of
bacteria was able to confer immunity and he
applied this principle to other organisms.
We now know that the molecular components
of pathogens generate immunity to a specific
disease by stimulating the immune system.
43

Antiseptics and Antibiotics Control
Pathogens
Before the work of Koch and Pasteur, many
people died of infections transmitted by their
own doctors.
• Ignaz Semmelweis ordered doctors to wash
their hands in chlorine, an antiseptic (a
chemical that kills microbes).
• The mortality rate fell, but other doctors
refused to accept Semmelweis’s findings.
44

Joseph Lister noted that half of his amputee
patients died of sepsis. He began to use
antiseptic agents (carbolic acid) to treat
wounds and surgical instruments.
By the 20th century, fully aseptic environments
(completely free of microbes) for surgery were
in use.
45

Although the use of antiseptics was a major
advance, they could not be taken internally, as
they would kill the patient.
Researchers sought a “magic bullet” or
antibiotic that would kill only the microbes,
leaving the host unharmed.
46

Alexander Fleming noted that a culture of
Staphylococcus contaminated with mold
caused a clearing of the bacteria nearby.
Fleming showed that the mold secreted a
substance that killed only the bacteria.
We now know this substance as penicillin.
47

48

The second half of the 20th century saw the
discovery of many powerful antibiotics.
• H. Florey & E. Chain purified penicillin and it
successfully saved the lives of many Allied
troops during WWII.
Today, widespread and indiscriminate use of
antibiotics has selected for pathogens that are
antibiotic resistant (lost effectiveness against
certain strains of major pathogens).
• Multi-drug resistant strains of M. tuberculosis
are now a serious threat to human health.
49

The Discovery of Viruses
Researchers were puzzled to find contagious
diseases whose agents of transmission could
pass through a filter with tiny pores that
blocked known bacterial cells.
• Martinus Beijerinck concluded that the cause of tobacco
mosaic disease could not be bacterial because it passed
through a filter that trapped bacteria.
• Wendell Stanley crystallized the infective particle and
called it tobacco mosaic virus (TMV).
50

51

© 2016 W. W. Norton Co., Inc. 52
1.4 Microbes in Our Environment – 1
Section Objectives
• Describe examples of how microbes contribute to
natural ecosystems.
• Explain how mitochondria and chloroplasts
evolved by endosymbiosis.

How do microbes shape the Earth’s
environment?
Microbes are responsible for cycling the many
minerals essential for all life.
Microbes make up most of the Earth’s
biosphere.
Earth’s ecology IS microbial ecology.

Microbes Support Natural Ecosystems
Sergei Winogradsky (1856–1953) was one of
the first to study microbes in their natural
habitats.
• Marshes/wetlands support microbes known
as lithotrophs, organisms that feed solely on
inorganic molecules.
• Winogradsky developed enrichment culture,
the use of selective growth media that support
certain classes of microbes while excluding
others.

55

Microbes Support Natural Ecosystems
geochemical cycling: the global interconversion of
inorganic and organic forms of nitrogen, sulfur,
phosphorus, and other minerals
Without essential conversions, such as nitrogen
fixation, no plants or animals could live.

Animals and Plants Evolved through
Endosymbiosis
Endosymbiosis (organisms living symbiotically inside a
larger organism) is widespread in all ecosystems.
Lynn Margulis (1938–2011) proposed that eukaryotic
cells were able to develop complex compartments such
as mitochondria and chloroplasts by engulfing and
merging with bacterial cells.

Endosymbiotic theory:
Respiring bacteria similar to E. coli were
engulfed by pre-eukaryotic cells, where they
evolved into mitochondria.
Similarly, a phototroph related to
cyanobacteria was taken up by a eukaryote,
giving rise to the chloroplasts of phototrophic
algae and plants.

59

Both mitochondria and chloroplasts contain their own
DNA sequences.
• Analysis of DNA provides compelling
evidence of the bacterial origin of
mitochondria and chloroplasts.
• Sequences show unmistakable homology
(similarity) to those of modern bacteria,
thus supporting their common ancestry.

New Microbes Continue to Emerge
We continue to discover surprising new microbes in
places previously thought uninhabitable, such as the hot
springs of Yellowstone National Park.
Bacterial DNA polymerase
from a hot spring is used
for PCR technology that
identifies pathogens in ill
patients.
61

In 1977, Carl Woese (1928–2012) discovered that
some of the microbes from Yellowstone hot springs
have DNA genomes very different from all other known
life forms.
The newly discovered
prokaryotes were seen
as a new form of life,
called archaea.
62

1.5 The DNA Revolution – 1
Section Objectives
• Describe how the structure of DNA was
discovered, and explain the significance of DNA
for determining the traits of life.
• Describe how the manipulation of DNA information
has transformed the practice of medicine.

How did science change medicine during
the 20th century?
DNA structure discovered by X-ray crystallography,
a method developed in the
UK in the early 1900s.
Dorothy Hodgkin (1910–1994) and Rosalind
Franklin (1920–1958) were pioneers in the
X-ray analysis field.

65

James Watson (b. 1928) and Francis Crick
(1916–2004) were the
first to understand that
DNA bases were
paired in the interior
of the double helix.
66

67

The discovery of the structure of DNA led to
the development of many new techniques and
technologies.
• A method of DNA sequencing, developed by
Frederick Sanger in 1977, was used to reveal
the first genome of a virus.
• The first genome sequence from a cellular
microbe (H. influenzae) was obtained in 1995.
• The same strategy was later applied to
sequencing the human genome.

20th century microbiology transformed the
practice of medicine and generated entire
industries of biotechnology and bioremediation.
Antibiotic development
Vaccine development
Biotechnology for diagnosis of disease
Microbial analysis in forensics
Bioremediation of wastes and control pests

Clicker questions – 1
Which of the following is NOT a microbe?
a. Escherichia coli, a bacterium living in the intestinal tract
b. Methanococcus jannaschi, an archaeon living a marsh
c. human immunodeficiency virus (HIV) infecting a patient’s
white blood cells
d. Pelomyxa species, a large ameba, living in a freshwater
pond
e. Taenia solium, a parasitic tapeworm found in swine
70

Clicker question answer – 1
Which of the following is NOT a microbe?
a. Escherichia coli, a bacterium living in the intestinal tract
b. Methanococcus jannaschi, an archaeon living a marsh
c. Human immunodeficiency virus (HIV) infecting a patient’s
white blood cells
d. Pelomyxa species, a large ameba, living in a freshwater
pond
e. Taenia solium, a parasitic tapeworm found in swine
71

Clicker question – 2
Antonie van Leeuwenhoek made which contribution to the
microbial world?
a. He was the first individual to observe single-celled
microbes.
b. He was the first microscopist to publish a study of the world
as seen under a microscope.
c. He sought to disprove the spontaneous generation of
microbes.
d. He discovered that fermentation was caused by yeast, a
single-celled fungus.
e. He was the first to attempt to quantify the role of disease in
population mortality.
72

Antonie van Leeuwenhoek made which contribution to the
microbial world?
a. He was the first individual to observe single-celled
microbes.
b. He was the first microscopist to publish a study of the world
as seen under a microscope.
c. He sought to disprove the spontaneous generation of
microbes.
d. He discovered that fermentation was caused by yeast, a
single-celled fungus.
e. He was the first to attempt to quantify the role of disease in
population mortality.
73

Which scientist was the first to develop a set of criteria to
establish a causative link between an infectious agent and a
disease?
a. Louis Pasteur
b. Lazzaro Spallanzani
c. Florence Nightingale
d. Robert Koch
e. Robert Hooke
74

Which scientist was the first to develop a set of criteria to
establish a causative link between an infectious agent and a
disease?
a. Louis Pasteur
b. Lazzaro Spallanzani
c. Florence Nightingale
d. Robert Koch
e. Robert Hooke
75

The first eukaryotic cells are thought to have originated by
which of the following processes?
a. symbiosis
b. endosymbiosis
c. pinocytosis
d. exocytosis
e. exosymbiosis
76

The first eukaryotic cells are thought to have originated by
which of the following processes?
a. symbiosis
b. endosymbiosis
c. pinocytosis
d. exocytosis
e. exosymbiosis
77

This concludes the
Lecture PowerPoint
presentation for
Chapter 1
78

Microbiology: The Human Experience PowerPoint Lecture ch 1

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