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Bacteria and Archaea

Bacteria and Archaea. The Prokaryotic Domains. Prokaryotic Complexity Figure 4.5. Eukaryotic Complexity Figure 4.7. Prokaryotes. derived from ancient lineages more biomass than all other life combined “simple” cellular structure no nuclear membrane no membrane-bound organelles

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Bacteria and Archaea

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  1. Bacteria and Archaea The Prokaryotic Domains

  2. Prokaryotic ComplexityFigure 4.5

  3. Eukaryotic ComplexityFigure 4.7

  4. Prokaryotes • derived from ancient lineages • more biomass than all other life combined • “simple” cellular structure • no nuclear membrane • no membrane-bound organelles • no cytoskeleton • limited morphological variation

  5. Prokaryotic MorphologiesFigure 27.13

  6. Prokaryotic Morphologies Figure 27.1

  7. photosynthetic bacteriaFigure 27.7

  8. photosynthetic archaeaFigure 27.20

  9. Prokaryotes • diverse metabolic “strategies” • photoautotrophy • chemoheterotrophy • most bacteria and archaea • chemoautotrophy • photoheterotrophy • energy from light • carbon from organic compounds

  10. Energy/carbonTable 27.2

  11. Prokaryotes • in nearly every habitat on Earth • terrestrial • aerobic/anaerobic • marine/freshwater • deep ocean rifts/deep in crust (>2 km) • antarctic ice pack • hot/acidic (>100˚C; pH = 2-3) • salty/alkaline (pH = 11.5) • etc.

  12. Prokaryotes • a range of growth rates • generation times • 10 min • 1-3 hours • days - weeks • suspensions between growth periods • indefinite • years, decades, >century, millions?

  13. Prokaryotes • Some defy taxonomic notions • get too big • possess internal membrane systems • exhibit “eukaryote-like” growth forms

  14. Actinomycete Figure 27.16

  15. MorphologyFigure 27.3 Diplococcus Neisseria gonorrhoeae Streptococcus pyogenes Staphylococcus aureus

  16. bacterial gas vesiclesFigure 27.4

  17. Prokaryotic Taxonomy • Historically • morphology • motility (+/-) • rolling/gliding • vertical positioning • flagella & axial filaments

  18. axial filamentsFigure 27.4

  19. flagellaFigure 27.5

  20. Prokaryotic FlagellumFigure 4.6

  21. Gram’s Stain: Bacillus subtilisgram positiveFigure 27.6

  22. Gram’s Stain:E. coligram negativeFigure 27.6

  23. Prokaryotic Taxonomy • Historically • morphology • motility • reactivity • Gram’s stain - peptidoglycan cell wall • metabolism • aerobic/anaerobic • resource utilization • products • inclusion bodies

  24. MycoplasmaFigure 27.17

  25. endospore - resting bodyFigure 27.14

  26. Prokaryotic Taxonomy • Historically • distinctive features • size • very large or very small • stress response • endospore formation • life style • colonial/parasitic/pathogenic

  27. Chlamydia: obligate intracellular parasiteFigure 27.13

  28. crown gall on geraniumdue to Agrobacterium tumefaciensFigure 27.10

  29. Prokaryotic Taxonomy • Pathogenic requirements • contact • entry • defense evasion • multiplication • damage • infectious transfer

  30. Prokaryotic Taxonomy • Pathogen characteristics • Invasiveness • Toxigenicity • Corynebacterium diphtheriae vs. Bacillus anthracis • endotoxin vs. exotoxin • Salmonella vs. Clostridium tetani

  31. Prokaryotic Taxonomy • Koch’s postulates • Always found in diseased individuals • Grown in pure culture from host inoculant • Cultured organisms causes disease • Newly infected host produces a pure culture identical to the infective culture

  32. Prokaryotic Taxonomy • Historically • distinctive features • size • very large or very small • stress response • endospore formation • life style • parasitic/pathogenic • ecological niche

  33. Methanogens & methane using Archaea • Methanogens release 80-90% of atmospheric methane, a greenhouse gas • Methane users intercept methane seeping from sub-oceanic deposits

  34. Prokaryotic Taxonomy • Biofilm production • on solid surfaces • mixed colonies • polysaccharide matrix • resistant to treatments

  35. Recent Prokaryotic Phylogeny • Based on rRNA • evolutionarily ancient • shared by all organisms • functionally constrained • changes slowly with time • encodes signature sequences • BUT - yields a different phylogeny than other sequences analyzed

  36. Recent Prokaryotic Phylogeny • sources of phylogenetic confusion • Lateral gene transfer • among members of bacterial species • among members of different species • across domains… • phylogenetic analysis assumes cladogenic evolution • evolution may have been highly reticulate

  37. Recent Prokaryotic Phylogeny • sources of phylogenetic confusion • Mutation • prokaryotes are haploid • “recessive” mutations are not masked • prokaryotes have very little non-coding DNA • many prokaryotes have very short generation times

  38. Recent Prokaryotic Phylogeny • rRNA led to three domains • Archaea: more similar to Eukarya than to Bacteria • An ancient split between Bacteria and Archaea was followed by a more recent split between Archaea and Eukarya

  39. The Three Domain PhylogenyFigure 27.2

  40. Shared Features of the Three Domains • plasma membrane • ribosome structure • glycolysis • encode polypeptide sequences in DNA • replicate DNA semi-conservatively • transcribe, translate with same genetic code

  41. Table 27.1

  42. some major bacterial groupsFigure 27.8

  43. Bacterial Phylogeny • Molecular comparisons suggest several higher level groups • Proteobacteria are highly diversified • gram negative • bacteriochlorophyll • source of mitochondria • N2-fixers, Rhizobium, Agrobacterium, E. coli, Yersinia, Vibrio, Salmonella, etc.

  44. ProteobacteriaFigure 27.9

  45. Bacterial Phylogeny • Molecular comparisons suggest several higher level groups • Proteobacteria are highly diversified • ancient Cyanobacteria produced oxygen and chloroplasts • “blue-green algae” • fix CO2 & N2 • single or colonial - sheets, filaments, balls

  46. Cyanobacteria fix CO2 & N2Figure 27.11

  47. Cyanobacteria are pond scumFigure 27.11

  48. Bacterial Phylogeny • Molecular comparisons suggest several higher level groups • Proteobacteria are highly diversified • ancient Cyanobacteria produced oxygen and chloroplasts • Spirochetes have axial filaments • human parasites & pathogens • free living in water sediments

  49. Spirochetes have axial filamentsFigure 27.12

  50. Bacterial Phylogeny • Molecular comparisons suggest several higher level groups • Proteobacteria are highly diversified • ancient Cyanobacteria produced oxygen and chloroplasts • Spirochetes have axial filaments • Chlamydias have a complex life cycle • obligate intracellular parasites

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