Transcript In Microbiology

Introduction and Overview of
General Microbiology
Lecture 1
What is Microbiology?
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In Microbiology- We Study
“Microbes”
What are microbes?
Micro- means small…
By definition, we study small
organisms…
those that we cannot see with the naked
eye…. (limit of resolution of eye = 0.2
mm)
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Biological Classification: The Five Kingdoms
(Whittaker) (based on morphological features)
Uni or multicellular
Eukaryotic
Eukaryotic
Unicellular
Bacteria
Archaea
Prokaryotic
Unicellular
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(Eu)Bacteria
Archaea
(Makes up 1 Kingdom – Monera)
Eukarya
(Make up other 4 Kingdoms)
Biological Classification Today –
3 Domain (Superkingdoms) System
(Woese)
(Based mainly on a gene sequence (DNA))
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Binomial Nomenclature
• Carolus (Carl) Linnaeus – 1750’s – probably not the first
person to do this but certainly made it popular and
acceptable
Homo sapiens – Homo is the genus (pl. genera), name can
only be used once… always capitalized
sapiens – species epithet… never capitalized and can be
used many times
Both the genus and species epithet make up the “species”
name
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What organisms do Microbes
include?
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1) Bacteria (Prokaryotes)
2) Viruses
3) Fungi (yeasts, molds)
4) Protista (protozoans)
5) Algae
6) Helminths
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2) Protista
1) Bacteria
Eukaryotic
(Eu)bacteria
Most Unicellular
Archaea
Archeabacteria 3) Fungi
Prokaryote
Eukaryotic
Unicellular
Uni- or multicellular
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4) Helminths
Multicellular eukaryotes
Roundworms
Flatworms
5) Viruses
Alive? Organisms?
Neither prokaryotic or
Eukaryotic…
6)Algae
Many are microscopic
We are really talking about Eukaryotic Types8
Types of Microorganisms
• Prokaryotes = Bacteria
• Unicellular organisms
Small in size
1000 X magnification
200 nm to 1 mm
• No compartmentalization
• No organelles
• No nucleus
Tremendous
• Cell wall
diversity
• All reproduce by binary fission or budding
• Ribosomes
• Plasma membrane
• Circular DNA chromosome
• Plasmids
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Prokaryotes
More in Chapter 4
2 Main Groups
1) Bacteria or Eubacteria (“True” Bacteria)
Non-archaea prokaryotes
Most have Peptidoglycan in the cell wall
2) Archaea
Possibly Ancient (hence the name)
Different structure & physiologies
Harsh environments
Extremophiles
No peptidoglycan in their cell wall
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Main Types of Bacteria
• Four main types - based on
morphology (shape)
bacillus (rod-shaped)
(pl. bacilli)
(sub-categories do exist (cocco-bacilli,
coccus (sphere-shaped)
(pl. cocci)
strep- staph- and diplo-
vibrios))
spirillum (pl. spirilla)
spirochete (corkscrew shaped)
helical – flattened “s”-shaped
(flexible cell wall)
non-flexible cell wall 11
Protista
• Eukaryotic microbes
• Most are unicellular
• Have no cell wall - only plasma membrane
May have pellicle
• Most are motile - distinguished by type of motility
• Pseudopods - cytoplasmic extensions, “false foot”
(amoebas)
• Flagella - “whip like” propellers (flagellates)
• Cilia - short hair-like structures coating entire surface
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(ciliates)
Fungi
• Eukaryotic organisms, extensive subcellular
compartmentalization
• Can be single or multicellular organisms (yeasts
mold hyphae)
• Cell wall is composed of chitin
• Can replicate either asexually (binary fission) or
sexually (mating)
• Obtain nutrients from surroundings
•Parasites or saprophytes
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Types of Fungi
Unicellular (Yeast)
Saccharomyces cerevisiae
Multi-cellular (Molds)
Penicillium
Multi-cellular
Mushrooms
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Algae
• Can be either unicellular or multicellular
• Photosynthetic eukaryotes
• Cellulose cell wall
• Exist in many environments (water and land)
• Photoautotrophs
• Consumed by animals as food
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Viruses
• Acellular
Electron microscope
• Simple virus
10 nm – 200 nm
• Capsid (protein)
• Nucleic acid (DNA or RNA)
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History of Microbiology
• Two major pioneers…
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Antonie van Leeuwenwoek –
first to visualize bacteria- created the
“simple” microscope (1660’s)
• Robert Hooke – devised the
“compound” microscope (1660’s) and
coined the term “cell”
•This turned out to be the beginning of the
end of “spontaneous generation”
(superstition)
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Spontaneous Generation
• Life arising from dead matter
• Maggots would “appear” on spoiled meat
• Fungi, insects, millipedes, and snakes found in rotten
logs
• Was believed life spontaneously generated from the
decomposing food
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First Evidence Against
“Spontaneous Generation” (life from non-life)
Francesco Redi - 1668
Several Days
Later
Spoiled Meat
Did not exclude the possibility of spontaneous
generation of bacteria
Maggots only appeared
if flask was open!
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Proponents of Spontaneous
Generation Battle Back!
• John Needham’s broth experiments - 1745
• Boiled broth was devoid of life
• Days later - teeming with microorganisms
• Argued that microbes could arise spontaneously from
non-living mater
• Lazzaro Spallanzani’s modification - 1765
• Only uncovered broth contained microorganisms
• Proponents argued that fresh air was required
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The Final Blow to the “Spontaneous
Generation” Hypothesis
* Louis Pasteur - 1861
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Significant Advances in Microbiology
• 1864 - Fermentation and Pasteurization - Louis Pasteur
• Discovered source of fermentation
• Yeast convert sugar to alcohol
• Bacteria cause spoiling - convert alcohol to vinegar
• Found heating perishables prevented spoiling – kills
bacteria
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Significant Advances in Microbiology
1876 - The Germ Theory of Disease proved correct
• Robert Koch developed “Koch’s Postulates” (4)
Anthrax decimating cattle industry
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1) Find evidence of a microbe in all infected individuals
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2) Isolate rod-shaped bacterium from infected individual
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3) Introduce bacterium to healthy individual and get same
disease
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4) Can reisolate the same bacterium from diseased
individuals
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Significant Advances in Microbiology
1796 - First successful vaccination - Edward Jenner
• Smallpox epidemics prevalent
• Cowpox caused similar disease in cattle – mild
disease in humans
• Jenner found infecting humans with cowpox
protected against smallpox infection
• Due to antigenic similarity between two viruses
(body recognizes these viruses as the same in some
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ways)
Significant Advances in Microbiology
1928 - Discovery of Antibiotics - Alexander Flemming
• Plate contaminated with
Penicillium
• Zone of inhibition
• Killed Streptococcus
• Called substance penicillin
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Fields of Microbiology
• Bacteriology - study of bacteria (includes Bacteria and Archaea)
• Mycology - study of fungi
• Parasitology - study of parasitic protozoa and worms
• Virology - study of viruses
• Immunology - study of the host response to infection
•Protozoology – general study of protozoa
•Algalogy – study of algae (for some might include cyanobacteria)
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Lecture 1 questions?