Download Chlamydia Figure 27.13

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
– no cytoskeleton
• limited morphological variation
Prokaryotic Morphologies
Figure 27.13
Prokaryotic Morphologies
Figure 27.1
photosynthetic bacteria
Figure 27.7
photosynthetic archaea
Figure 27.20
Prokaryotes
• diverse metabolic “strategies”
– photoautotrophy
– chemoheterotrophy
• most bacteria and archaea
– chemoautotrophy
– photoheterotrophy
• energy from light
• carbon from organic compounds
Energy/carbon
Table 27.2
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.
Prokaryotes
• a range of growth rates
– generation times
• 10 min
• 1-3 hours
• days - weeks
– suspensions between growth periods
• indefinite
–years, decades, >century, millions?
Prokaryotes
• Some defy taxonomic notions
– get too big
– possess internal membrane systems
– exhibit “eukaryote-like” growth forms
Actinomycete
Figure 27.16
Morphology
Figure 27.3
Diplococcus
Neisseria gonorrhoeae Streptococcus pyogenes Staphylococcus aureus
bacterial gas vesicles
Figure 27.4
Prokaryotic Taxonomy
• Historically
– morphology
– motility (+/-)
• rolling/gliding
• vertical positioning
• flagella & axial filaments
axial filaments
Figure 27.4
f
l
a
g
e
l
l
a
Figure 27.5
Prokaryotic
Flagellum
Figure 4.6
Gram’s Stain:
Bacillus subtilis
gram positive
Figure 27.6
Gram’s Stain:
E. coli
gram negative
Figure 27.6
Prokaryotic Taxonomy
• Historically
– morphology
– motility
– reactivity
• Gram’s stain - peptidoglycan cell wall
• metabolism
–aerobic/anaerobic
–resource utilization
–products
–inclusion bodies
Mycoplasma
Figure 27.17
endospore - resting body
Figure 27.14
Prokaryotic Taxonomy
• Historically
– distinctive features
• size
–very large or very small
• stress response
–endospore formation
• life style
–colonial/parasitic/pathogenic
Chlamydia: obligate intracellular parasite
Figure 27.13
crown gall
on geranium
due to
Agrobacterium
tumefaciens
Figure 27.10
Prokaryotic Taxonomy
• Pathogenic requirements
– contact
– entry
– defense evasion
– multiplication
– damage
– infectious transfer
Prokaryotic Taxonomy
• Pathogen characteristics
– Invasiveness
– Toxigenicity
• Corynebacterium diphtheriae vs. Bacillus
anthracis
• endotoxin vs. exotoxin
–Salmonella vs. Clostridium tetani
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
Prokaryotic Taxonomy
• Historically
– distinctive features
• size
–very large or very small
• stress response
–endospore formation
• life style
–parasitic/pathogenic
• ecological niche
Methanogens & methane using Archaea
• Methanogens release 80-90% of atmospheric
methane, a greenhouse gas
• Methane users intercept methane seeping from
sub-oceanic deposits
Prokaryotic Taxonomy
• Biofilm production
– on solid surfaces
– mixed colonies
– polysaccharide matrix
– resistant to treatments
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
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
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
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
The Three Domain Phylogeny
Figure 27.2
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
Table 27.1
some major
bacterial groups
Figure 27.8
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.
Proteobacteria
Figure 27.9
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
Cyanobacteria fix
CO2 & N2
Figure 27.11
Cyanobacteria are pond scum
Figure 27.11
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
Spirochetes have axial filaments
Figure 27.12
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
Chlamydia Figure 27.13
Bacterial Phylogeny
• Molecular comparisons suggest several higher
level groups
– Firmicutes: a diverse (mostly) Gram positive
group
• some produce endospores
• some are native flora
–Staphylococcus
Figure 27.15
Gram +
staphylococci
Bacterial Phylogeny
• Molecular comparisons suggest several higher
level groups
– Firmicutes: a diverse (mostly) Gram positive
group
• some produce endospores
• some are native flora
• some are filamentous (actinomycetes)
–Mycobacterium tuberculosis
–Streptomyces spp.
filamentous Actinomycete
Figure 27.16
Bacterial Phylogeny
• Molecular comparisons suggest several higher
level groups
– Firmicutes: a diverse (mostly) Gram positive
group
• some produce endospores
• some are native flora
• some are filamentous (actinomycetes)
• Mycoplasmas
–small (~0.2 µm), no cell wall, low DNA
Mycoplasma Figure 27.17
unique
membrane
structure
Figure
27.18
unique
membrane
structure
See page
539
Archaean Phylogeny
• Most known archaea are extremophiles
– many are not
• Archaea cell walls lack peptidoglycan
• Archaea possess unique cell membranes lipids
• Archaea share rRNA signature sequences
• >1/2 of Archaean genes are unlike genes
known from Bacteria or Eukaryotes
Archaean Phylogeny
• Crenarchaeota
– most live in hot, acidic habitats
• 70-75˚C; pH 2-3
–Sulfolobus pH = 0.9
–Ferroplasma pH = 0.0
–some maintain internal pH 7.0
a hot,
acidic
home
Figure
27.19
Archaean Phylogeny
• Crenarchaeota
– most live in hot, acidic habitats
• Euryarchaeota
– Methanogens [CO2 => CH4]
• strict anaerobes in cow guts, rice paddies
and hydrothermal vents
• all share rRNA similarities
Archaean Phylogeny
• Crenarchaeota
– most live in hot, acidic habitats
• Euryarchaeota
– Methanogens
– extreme halophiles
• e.g. in the Dead Sea
• some use bacteriorhodopsin (retinal), not
bacteriochlorophyll
Archaean Phylogeny
• Crenarchaeota
– most live in hot, acidic habitats
• Euryarchaeota
– Methanogens
– extreme halophiles
– Thermoplasma
• thermoacidophile, no cell wall
• genome size = Mycoplasmas (1.1 x 106)