BIOL 260-General Microbiology
Instructor: Christopher Thor
Masters Degree, Bioengineering
Bachelors Degree, Molecular Biology
Welcome to BIOL 260: Microbiology!
• First day:
– Review of Syllabus
– Sign-in
– Introduce the course, review course
expectations
– Begin with first lab
• Exercise 3: Microscope Lab
What is microbiology?
• The scientific discipline which studies
microbes or microorganisms
– Biology of microbes
– The interaction of microbes with other
microbes, the environment, and humans
The “Yotes”
Definitions:
Prokaryote: Single celled organism, no
nucleus.
Bacteria, Archaea
Eukaryote: Single or multi-celled organism,
membrane bound nucleus
Algae, Protozoa, Fungi, people
What are examples of microbes?
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Algae
Fungi
Protozoa
Bacteria
Viruses
Which are Prokaryotes are which are Eukaryotes?
Hierarchy
Types of Microbes: Algae
Types of Microbes: Protozoa
Types of Microbes: Fungi
Types of Microbes: Bacteria
Viruses, Viroids, Prions
Microorganisms are associated with
• Disease
– Cause of many epidemics in history
– Bubonic plague (1346-1350)
• Killed 25 million people
– Small pox
• Killed estimated 600 million people
since 10,000 BC
• Eradicated in 1979
– HIV
• 3.1 million estimated new cases per year
• 5% of Sub-Saharan Population
– Malaria
Small Pox
Bacteria are associated with
• Normal microbiota (normal flora)
– The bacteria that are present on our bodies
Bacteria are associated with
• The environment
– Rhizobium (the greatest bacteria you’ve never heard of)
• Nitrogen fixation in the soil
• Food products
– Beer! Or bread, wine, sauerkraut, yogurt,
cheese…
• Medicines
– Bacteria are “programmed” to make insulin
History of Microbiology
• It all started with the microscope!
– Zacharis Janssen (1600)
– Antoni van Leewenhoek (1632-1723)
– Robert Hooke (1665)
Zacharis Janssen’s microscope
• Modeled after the
telescope
• Consisted of two
lenses
• Magnified images 310X
Leewenhoek’s microscope
20-30x magnification
Where do cells come from?
• Spontaneous generation
– Francesco Redi (1668)
• Spontaneous Generation does not occur
– John Needham (1745)
• Spontaneous Generation does occur
– Lazzaro Spallanzani (1765)
– Louis Pasteur (1861)
• Biogenesis
– Rudolf Virchow (1858)
• Living things come from living things
Pasteur’s flasks
John Tyndall questions Pasteur’s
experiments
• Could not reproduce Pasteur’s results
– Specific growth media required
– Found that there were heat resistant forms of
microbes
• Same year (1876) Ferdinand Cohn discovers heat
resistant forms of bacteria called endospores
– Spores can survive in space (Apollo Program,
1960s)
• 1877 Robert Koch demonstrates that anthrax caused
by Bacillus anthracis
Major Milestones in Microbiology
Major Milestones in Microbiology
New cells need to be placed in categories
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Aristotle-plant or animal kingdom
Kingdom Protista (1866)
Electron microscope (1940’s)
Kingdom Procaryotae (1968)
Carl Woese proposed 3 Domains (1978)
Three Domain System
Prokaryotes (Single Celled)
• Bacteria Domain (Eubacteria)
– Peptidoglycan cell walls
• Gram negative
• Gram positive
• Archaea Domain (Archaebacteria)
– Not a peptidoglycan cell wall
– Extremophiles
• Methanogens
• Halophiles
• Thermophiles
Binomial system of nomenclature
• Genus and species
– Escherichia coli, E. coli
• Both names are in italics or underlined and
correctly spelled.
Relationship of size and
resolution
Types of microscopes
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Brightfield
Darkfield
Phase Contrast
Fluorescent
Electron
Microscopy-Brightfield
Oil has same refractive index as
glass
Microscopy
Stained specimen
Wet mount
Microscopy
Stained specimen
Wet mount
Microscopy
Electron microscopes - maximum magnification 100,000X
Microscopy
Electron microscopes - maximum magnification 100,000X
“Color-enhanced”
Staining: key to visualization
• Simple
• Differential
• Special
Microscopic Techniques: Dyes and
Staining
•Simple stains
• Stains everything
•Differential stains
• Stain based on cellular traits
Gram stain - separates
bacteria into two categories
based on type of cell wall
Acid Fast Stain – Stains
non-peptidoglycan containing
bacteria (Mycobacteria)
Gram-positive
Gram-negative
Microscopic Techniques: Dyes and
Staining
•Simple stains
•Differential stains
Gram stain - separates
bacteria into two categories
based on type of cell wall
Purple: Bacteria with high
peptidoglycan containing
cell walls
Pink: Counter stain
Differential Stain: Acid Fast
Microscopic Techniques: Dyes and
Staining
Fluorescent dyes and tags
Special stain: Capsule Stain
Special stain: Endospore Stain
Special stain: Flagella Stain
Morphology of
Prokaryotic Cells:
Cell Shapes
Morphology of Prokaryotic Cells:
Cell Shapes
Morphology of Prokaryotic Cells:
Cell Groupings
Morphology of Prokaryotic Cells:
Multicellular Associations
Biofilm containing mixed species