630 Microbiology for Teachers

Microbial Evolution and Systematics

Physical Evolution of Earth

• Big Bang

   

• Patchy condensation

   

• Planet Earth formed

   

  • geology
    • inner core (0-1227km)

       

    • outer core (1227-3486km)

       

    • mantle (3486-6350km)

       

    • crust (6350km-surface)

       

      • oceanic crust

         

      • continental crust

         

  • primitive atmosphere
    • reducing

       

    • mildly oxidizing

       

  • liquid water

     

Origin of Life on Earth

• Primordial soup (solution) theory
  • chemical reactions

     

  • accumulation

     

  • spontaneous aggregation

     

  • anaerobic thermophilic fermenters

     

• Surface theories
  • pyrite theory

     

  • clay theory

     

  • thermophilic anaerobic lithotrophs

     

Early Evolution of Organisms with Increasing Complexity

• Fossils

   

• Mutations

   

  • Anoxygenic photosynthesizers

     

  • Oxygenic photosynthesizers

     

Atmosphere Evolved as Microbes Produced Oxygen ~2.5 Ba

• Oxygen content slowly increased

   

• Ozone layer formed as UV light energy was absorbed by oxygen

   

Atmospheric Oxygen Availability Led to Increasing Diversity

• Microbial diversity increased ~0.5 billion years after oxygen generation began

   

• "Modern" eukaryotes evolved ~1.3 Ba (1.2 billion years after oxygen generation began)

   

  • eukaryotic diversity

     

  • metazoans

     

Broad Evolutionary Picture

• Original organism

   

• Universal ancestor

   

Classification

• Phylogeny vs. Taxonomy

   

• Binomial nomenclature

   

Molecular Approaches to Phylogeny

• Attributes of acceptable molecules

   

  • universally distributed

     

  • functionally homologous

     

  • alignable

     

  • slow rate of sequence changes

     

• Molecules used
  • proteins

     

  • 5S rRNA

     

  • ATP synthase

     

  • 16S rRNA (18S rRNA in eukaryotes)

     

    • determine primary rRNA structure

       

    • analyze rRNA sequence homology
      • (cataloging (80%) - signature sequences

         

      • (distance matrix (20%) - ED calculated

         

  • Ef-Tu and Ef-G (used to "root" 3-domain tree)

     

Bacteria, Archaea and Eukarya

• Bacterial Phylogeny
  • Aquificales - Aquifex

     

  • Thermotogales - Thermosipho and Thermatoga

     

  • Green Nonsulfur Bacteria(phototrophs and nonphototrophs)
    Chloroflexus and Thermomicrobium

     

  • Deinococcus/Thermus group

     

  • Proteobacteria (ancestors were phototrophs)

     

    • alpha group (phototrophs, lithotrophs, organotrophs)
      Rhodobacter, Rhizobium, Nitrobacter, Aquaspirilum, Hyphomicrobium, Acetobacter, Methylcoccus, Pseudomonas

       

    • beta group (phototrophs, lithotrophs, organotrophs)
      Rhodocyclus, Spirilum, Nitrosomonas, Sphaerotilus, Thiobacillus, Alcaligenes, Pseudomonas, Neisseria

       

    • gamma group (phototrophs, lithotrophs, organotrophs)
      Chromatium, Thiospirillum, Beggiatoa, Leucothrix, enterics, Legionella, Azotobacter, Pseudomonas, Vibrio

       

    • delta group (organotrophs)
      Myxobacteria, Bdellovibrio, Desulfovibrio, Desulfuromonas

       

    • epsilon group (lithotrophs, organotrophs)
      Thiovulum, Wolinella, Campylobacter, Helicobacter

       

  • Cyanobacteria (share last ancestor with proteobacteria)

     

  • Gram-Positive Bacteria (share last ancestor with proteobacteria)

     

  • Spirochetes

     

  • Bacteroides/Flavobacterium group

     

  • Green Sulfur Bacteria (share last ancestor with Bacteroides/Flavobacterium group)

     

  • Planctomyces/Pirella group

     

  • Chlamydia

     

• Archaeal Phylogeny

   

  • Korarchaeota (newly discovered extreme thermophiles; most primitive life forms discovered to date)

     

  • Crenarchaeota (includes extreme thermophiles and marine cryophiles)
    Thermofilum, Thermoproteus, Pyrodictium, Desulfurococcus, Sulfolobus in addition to a number of as yet unidentified marine Crenarchaeotes

     

  • Euryarchaeota (includes methanogens, sulfur utilizers, extreme thermophiles and extreme halophiles)
    Methanopyrus, Thermococcus, Methanococcus, Archaeoglobus, Thermoplasma, Methanothermus, Methanobacterium, Methanospirillum, Haloferax, Halococcus, Halobacterium

     

• Eukaryal Phylogeny

   

  • Groups of Eukarya

     

    • Protozoa

       

    • Fungi

       

    • Plants

       

    • Animals

       

  • Endosymbiotic theory of eukaryotic organelle origin and evolution 
    • evidence

       

    • endosymbiosis has been proposed as the mechanism underlying the origin and evolution of mitochondria and chloroplasts in Eukarya