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
parasitolo
gy
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 bodyMicrobes— Lactobacillius acidophilus —make yogurtOthers 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
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?
Did you know?
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
What is systematics?
Study of phylogenetic relationships Phylogenetic
s = ________ Taxonomy =
__________
Also a way of organizing/ classifying Taxa (taxon
—singular)
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
Look at the background!
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
Archaea
Cell type
Cell wall
Organelles/ nucleus?
Sensitive to antibiotic?
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
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
So how can we tell them apart?
What are bacteria? Simple, single-
celled 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
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,
heated, not sealed
Microbial growth
Nutrient broth placed in flask,
heated, then sealed
No microbial growth
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 engineeringUN 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.