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?
 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
Virus, viroids and prions
 Why not?
 Viral species: population of viruses with
similar characteristics
A closer look at the microbes
What are bacteria?
 Simple, singlecelled
 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
 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
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