The Microbial World and You
The Microbial World and You
 Microorganisms
 too small to be seen
with unaided eye
 “Germ”
 rapidly growing cell
What are microbes?
 Fungi (molds,
yeasts)
 mycology
 Protozoa
 parasitology
 Microscopic
algae
 phycology
What do they do?

Decompose
 organic waste

Producers in the ecosystem
 by photosynthesis

Produce industrial chemicals
 Ethanol and acetone

Produce fermented foods
 vinegar, cheese, and bread

Produce manufacturing products
 (e.g., cellulase) and treatment
(e.g., insulin)

A few are pathogenic,

disease-causing
Microbes everywhere on your body
Microbes— Lactobacillius
acidophilus —make yogurt
Others make beer and wine—
Saccharaomyces cereviceae
The better question might be, “what don’t they
do?”
 Allows humans to
 Prevent food spoilage
 Prevent disease occurrence
 Led to aseptic techniques to
prevent contamination in
medicine and in
microbiology laboratories
Did you know?
 Bacteria causes body
odor
 Bacteria, tiny as they
are, can get sick, too!
 Under the right
conditions a
bacterium like
Escherichia coli can
grow from just one
cell to 1 million cells
in less than 7 hours!
 How their size
compares?
How are microbes named and classified?
 Linnaeus established
 system of scientific
nomenclature.
 Each organism has two
names:
 genus and specific
epithet.
 Are italicized or
underlined. The genus is
capitalized and the specific
epithet is lower case.
 Are “Latinized” and used
worldwide.
 May be descriptive or
honor a scientist.
Scientific Names
 Staphylococcus aureus
 Describes the clustered arrangement of the cells
(staphylo-) and the golden color of the colonies
(aur-).
 Escherichia coli
 Honors the discoverer, Theodor Escherich, and
describes the bacterium’s habitat–the large intestine
or colon
Taxonomy
What is systematics?
 Study of
phylogenetic
relationships
 Phylogenetics
= ________
 Taxonomy =
__________
 Also a way of
organizing/
classifying
 Taxa (taxon—
singular)
Look at the
background!
 Plant and Animal Kingdoms
 Bacteria and fungi
 put in the Plant Kingdom
 Kingdom Protista proposed
 for bacteria, protozoa, algae, and fungi
 Prokaryote introduced for cells "without a nucleus“
 Prokaryote defined as cells in which nucleoplasm is
not surrounded by a nuclear membrane
 Kingdom Fungi
 Kingdom Prokaryotae proposed
 Two types of prokaryotic cells found
How are prokaryotes classified?
 Use Bergey’s Manual
of Systemic
Bacteriology
 Divides prokaryotes
into (based on rRNA
sequences)
 Bacteria
 Archaea
Who is Carl Woese?
1978: created current
classification scheme
 Three domains
 Bacteria
 Archaea
 Eukarya
 Protists
 Fungi
 Plants
 Animals
What are the key differences between the three divisions?
Eukaryotes Prokaryotes
Cell type
Cell wall
Organelles/
nucleus?
Sensitive to
antibiotic?
Archaea
What is the taxonomy of organisms?
 Domain
 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species
How are eukaryotes classified?
 Endosymbiotic
theory
 Numerous
kingdoms, including
 Protista
 Fungi
 Plantae
 Animalia
What about viruses—How are they classified?
 Not included in three domains, which are
_______ _______ and ______
 Why not?
 Viral species: population of viruses with
similar characteristics
How do I tell prokaryotes apart?
 Really difficult
 Morphology is very similar!
B. anthracis
B. japonicum
So how can we
tell them apart?
 Lab techniques such as
 Staining
 Gram positive vs.
Gram negative
So how can we tell them apart?
 Biochemical test
 Different bacteria will
grow on different
types of media
 Carbohydrates
 Proteins
 Serology
 Slide agglutination
test
 Look for clumping of
bacteria with
antiserum
 Serotypes are
strains with
different antigens
 DNA fingerprinting
 rRNA sequencing
A closer look at the microbes
What are bacteria?
 Simple, singlecelled
 ubiquitous
 Prokaryotes
 DNA is not
inside a
membrane
 Come in different
shapes
 Coccus (cocci,
plural)
 Bacillus (bacilli,
plural)
 Spiral
(corkscrew,
comma or
curved)
 Peptidoglycan cell
wall
 Binary fission
 Some have flagella
What are archaea?
 Also prokaryotes
 Cells wall do not have peptidoglycan
 Live in extreme conditions
 Extreme halophiles
 Hyperthermophiles
 Methanogens
 Not pathogenic
Figure 4.5b
What are fungi?
 Eukaryotes
 Have a true nucleus
 More closely related to
__________
 wall of chitin
 Uni- and multicellular
 Includes
 Molds
 Mushrooms
 Yeasts
 Slime molds
 Sexual and asexual
reproduction
Figure 1.1b
What are protozoa?
 Eukaryotes
 Absorb or ingest
organic chemicals
 May be motile via
pseudopods, cilia,
or flagella
Figure 1.1c
What are algae?
 Eukaryotes
 Cellulose cell walls
 Use photosynthesis for
energy
 Produce molecular oxygen
and organic compounds
Figure 1.1d
What are viruses?
 Acellular
 Consist of DNA or RNA core
 Core is surrounded by a
protein coat.
 Coat may be enclosed in a
lipid envelope.
 Viruses are replicated only
when they are in a living
host cell.
Figure 1.1e
What are multicellular animal parasites?
 Eukaryote
 Multicellular animals
 Parasitic flatworms and round worms are called
helminths.
 Microscopic stages in life cycles.
Figure 12.28a
Brief History of Microbiology
The First Observations
 Ancestors of bacteria were
 first life on Earth.
 observed in 1673.
 1665, Robert Hooke reported
 living things were composed of little boxes or cells.
 1858, Rudolf Virchow
 cells arise from preexisting cells.
 Cell theory: All living things are composed of cells and
come from preexisting cells.
How did we discover microbes?
 Before the microscope:
 Spontaneous generation
 “vital force” forms life.
 Microscope
 Van Leeuwenhoeke, 1670s
 Louis Pasteur, 1861
 Showed microorganisms are in the air
 Refutes spontaneous generation with biogenesis
 Used curved flask
Conditions
Results
Nutrient broth placed in flask, Microbial growth
heated, not sealed
Nutrient broth placed in flask, No microbial growth
heated, then sealed
Spontaneous generation or biogenesis?
When was the golden age of microbiology?
 1857-1914
 Pasteurization
 Developed after investigation of fermentation
 Demonstration of aseptic technique
 microbes are responsible for fermentation.
 Fermentation
 conversion of sugar to alcohol to make beer and wine.
 Microbial growth
 responsible for spoilage of food.
 Pasteur demonstrated
 spoilage bacteria killed by heat
 Pasteruization
 high heat for a short time.
The Germ Theory of Disease
 Joseph Lister, 1860s used a chemical disinfectant to prevent
surgical wound infections
 Germ theory of disease
 Robert Koch, 1876, Germany
 Bacillus anthracis causes anthrax
 provided the experimental steps
 Vaccination
 Edward Jenner, 1796
 Small pox and cow pox
 Immunology
What about modern microbiology?
 1928: Alexander Fleming
 first antibiotic.
 Penicillium fungus made
 antibiotic, penicillin, that
killed S. aureus.
 1940s: Penicillin was tested
clinically and mass
produced.
Figure 1.5
Some terms in microbiology
 Bacteriology is the study of bacteria.
 Mycology is the study of fungi.
 Parasitology is the study of protozoa and parasitic
worms.
 Immunology is the study of immunity. Vaccines and
interferons are being investigated to prevent and cure
viral diseases
 Virology is the study of viruses.
Some modern concepts
 Bioremediation
 degrade organic matter in
sewage.
 degrade or detoxify
pollutants such as oil and
mercury.
 Biological Insecticides
 Biotechnology
 Genetic engineering
UN 2.1
What is normal microbiota?
 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.
What are infectious diseases?
 When a pathogen overcomes the host’s resistance,
disease results.
 Emerging infectious diseases (EID): New diseases and
diseases increasing in incidence.






West Nile Virus
Bovine spongiform encephalopathy
Ebola hemorrhagic fever
Hantavirus
AIDS
Anthrax