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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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Eukarya
(Eu)Bacteria
Archaea
(Make up other 4 Kingdoms)
(Makes up 1 Kingdom Monera)
Biological Classification Today 3 Domain
(Superkingdoms) System (Woese) (Based mainly on a
gene sequence (DNA))
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Binomial Nomenclature

• Carolus (Carl) Linnaeus 1750s 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?

• 1) Bacteria (Prokaryotes)
• 2) Viruses
• 3) Fungi (yeasts, molds)
• 4) Protista (protozoans)
• 5) Algae
• 6) Helminths

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2) Protista Eukaryotic Most Unicellular
1) Bacteria (Eu)bacteria Archaea Archeabacteria Pr
okaryote Unicellular
3) Fungi Eukaryotic Uni- or multicellular
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4) Helminths Multicellular eukaryotes Roundworms F
latworms
5) Viruses Alive? Organisms? Neither prokaryotic
or Eukaryotic
6)Algae Many are microscopic We are really
talking about Eukaryotic Types
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Types of Microorganisms

• Prokaryotes Bacteria
• Unicellular organisms
• No compartmentalization
• No organelles
• No nucleus
• Cell wall
• All reproduce by binary fission or budding
• Ribosomes
• Plasma membrane
• Circular DNA chromosome
• Plasmids

Small in size 1000 X magnification 200 nm to 1 mm
Tremendous diversity
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Prokaryotes 2 Main Groups
More in Chapter 4
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)

coccus (sphere-shaped)
bacillus (rod-shaped)
(pl. cocci) strep- staph- and diplo-
(pl. bacilli) (sub-categories do exist
(cocco-bacilli, vibrios))
spirillum (pl. spirilla) helical flattened
s-shaped non-flexible cell wall
spirochete (corkscrew shaped) (flexible cell wall)
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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
• (ciliates)

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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
Multi-cellular (Molds) Penicillium
Unicellular (Yeast) Saccharomyces cerevisiae
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
• Simple virus
• Capsid (protein)
• Nucleic acid (DNA or RNA)

Electron microscope 10 nm 200 nm
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History of Microbiology

• Two major pioneers
• Antonie van Leeuwenwoek
• first to visualize bacteria- created the
  simple microscope (1660s)
• Robert Hooke devised the compound microscope
  (1660s) 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
Maggots only appeared if flask was open!
Spoiled Meat
Did not exclude the possibility of spontaneous
generation of bacteria
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Proponents of Spontaneous Generation Battle Back!

• John Needhams 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 Spallanzanis 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 Kochs Postulates (4)
• Anthrax decimating cattle industry
• 1) Find evidence of a microbe in all infected
  individuals
• 2) Isolate rod-shaped bacterium from infected
  individual
• 3) Introduce bacterium to healthy individual and
  get same disease
• 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 ways)

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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?