Welcome to Microbiology BIO 187

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Welcome to MicrobiologyBIO 187
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Chapters 1 2 Overview of Microorganisms and
Microbiology
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Whats so important about these guys anyway????

• Without microorganisms all higher life forms on
  Earth would cease to exist sounds pretty
  important to me!
• Collectively microorganisms constitute the
  greatest amount of Biomass on Earth.
• Pathogenicity
• Adaptation to Change and Evolution
• Great genetic, physiological, and metabolic
  diversity. Earths Greatest Chemists
• Foundation for our understanding of complex life
  processes.

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Microorganisms as cells

• Characteristics of living systems-Hallmarks of
  Cellular Life
• Metabolism
• Reproduction (growth)
• Differentiation
• Communication
• Movement
• Evolution

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Microorganisms as cells

• Cell Structure
• Viruses are not cells (infectious particles) 
• Universal Ancestor of all life
• Cell Theory
• all living things are composed of cells
• all cells come from preexisting cells

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Classification

• 3 Domains
• Bacteria
• Archaea
• Eukarya
• Binomial Nomenclature
• Genus species Escherichia coli
• Hierarchy of taxonomic units
• Domain ? Kingdom ? Phylum ? Class ? Order ?
  Family ? Genus ? species

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Microbial Populations, Communities, and Ecosystems

• Populations
• Microbial Communities
• Habitat
• Ecosystem

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The Impact of Microorganisms on Humans

• Microorganisms can be both beneficial and harmful
  to humans
• Emphasis typically on harmful microorganisms
  (infectious disease agents, or pathogens)
• But many more microorganisms in nature are
  beneficial than are harmful

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Death Rates and the Leading Causes of Death in
the U.S.
Microorganisms as Disease Agents Control of
infectious disease during last century
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The Impact of Microorganisms on Humans

• Microorganisms and Agriculture
• Many aspects of agriculture depend on microbial
  activities
• Nitrogen-fixing bacteria
• Cellulose-degrading microbes in the rumen
• Regeneration of nutrients in soil and water

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The Impact of Microorganisms on Humans
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The Impact of Microorganisms on Humans

• Microorganisms and Food
• Negative impacts
• Food spoilage by microorganisms requires
  specialized preservation of many foods
• Positive impacts
• Microbial transformations (typically
  fermentations) yield
• Dairy products (e.g., cheeses, yogurt,
  buttermilk)
• Other food products (e.g., sauerkraut, pickles,
  leavened breads, beer)

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The Impact of Microorganisms on Humans

• Microorganisms, Energy, and the Environment
• The role of microbes in biofuels production
• e.g., methane, ethanol, hydrogen
• The role of microbes in cleaning up pollutants
  (bioremediation)

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The Impact of Microorganisms on Humans

• Microorganisms and Their Genetic Resources
• Exploitation of microbes for production of
  antibiotics, enzymes, and various chemicals
• Genetic engineering of microbes to generate
  products of value to humans, such as insulin
  (biotechnology)

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Very Brief History of Microbiology

• Robert Hooke (1635-1703) was the first to
  describe microbes
• Anton van Leeuwenhoek (1632-1723) was the first
  to describe bacteria (Father of Microbiology)
• Further progess required development of more
  powerful microscopes

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Pasteur and the Defeat of Spontaneous Generation

• Louis Pasteur (1822-1895)
• Discovered that living organisms discriminate
  between optical isomers
• Discovered that alcoholic fermentation was a
  biologically mediated process (originally thought
  to be purely chemical)
• Disproved theory of spontaneous generation
• Led to the development of methods for controlling
  the growth of microorganisms
• Developed vaccines for anthrax, fowl cholera, and
  rabies

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The Defeat of Spontaneous Generation Pasteurs
Experiment
Figure 1.13a
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The Defeat of Spontaneous Generation Pasteurs
Experiment
Figure 1.13b
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The Defeat of Spontaneous Generation Pasteurs
Experiment
Figure 1.13c
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Robert Koch

• Robert Koch (1843-1910)
• Definitively demonstrated the link between
  microbes and infectious diseases
• Identified causative agents of anthrax and
  tuberculosis
• Developed techniques (solid media) for obtaining
  pure cultures of microbes, some still in
  existence today
• Awarded Nobel Prize for Physiology and Medicine
  in 1905
• Kochs postulates

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Kochs Postulates
Figure 1.15
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Kochs Postulates
Figure 1.15
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Microscopy
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Compound Light Microscopy
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Compound Light Microscopy

• Magnification
• Resolution capacity to distinguish as separate 2
  adjacent points. Max resoultion of light
  microscope is 0.2 micrometers (2 points closer
  than 0.2 apart appear as one)
• Refractive Index measure of speed at which light
  passes through a material (staining increases the
  difference between refractive indexes of specimen
  and the mediumso contrast is increased)
• Brightfield illumination

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Some microorganisms are pigmented. Most are not.
Green algae
Purple phototrophic bacteria
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Staining

• Basic dyes (positive ion colored)
• Positive stains
• Acidic dyes (negative ion colored)
• Negative stains

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Steps in smear preparation and staining
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The Gram Stain (a differential stain)
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Gram StainPositive cocci and Negative rods
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Darkfield microscopy(specimem appears light
against a black background)(good for seeing
motility and very small or thin microbes)Phase
Contrast(enhances differences in refractive
indexes of structures, soyields increase
contrast) (good for seeing internal structures of
living cells)
Borrelia burgdorferi
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Darkfield
Phase contrast
Brightfield
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Cyanobacteria stained with fluorescent dye
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Three-Dimensional Imaging
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Differential Interference Contrast Microscopy
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Atomic Force Microscope (AFM)
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Confocal Scanning Laser Microscopy
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Electron Microscopy
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TEM Transmission Electron Microscopy
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SEM Scanning Electron Microscopy
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CELL SIZE (an upper limit is imposed by surface
to volume ratio)
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Prokaryotes and Eukaryotes compared

• Similarities
• Genetic material
• Cellular chemistry and metabolic pathways
• Some structures and functions

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Prokaryotes and Eukaryotes compared

• Differences (compartmentalization)
• Prokaryotes
• DNA NOT enclosed by membrane
• No membrane-bound organelles
• No histone proteins associated with DNA
• Complex cell walls
• Division by binary fission
• Eukaryotes
• DNA with a nucleus
• Membrane-bound organelles
• Histone proteins
• Cell walls absent or simple
• Division by mitosis

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• BASIC SHAPES
• Coccus
• Rod
• Spiral