The Prokaryotes: Domains Bacteria and Archaea

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The Prokaryotes Domains Bacteria and Archaea

• One circular chromosome
• not in a membrane
• No histones
• No organelles
• Peptidoglycan cell walls (bacteria)
• Pseudomuerin cell walls (archaea)
• Binary fission

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Domain Bacteria

• Proteobacteria
• Largest taxonomic group of bacteria
• Mythical Greek god, Proteus, who could assume
  many shapes
• Subgroups are designated by Greek letters
• Includes most of the gram-negative bacteria
• Phylogeny based on rRNA studies
• Common photosynthetic ancestor
• few are still photosynthetic

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The ? (alpha) Proteobacteria

• Some grow at low nutrient levels
• Some have unusual morphology
• prosthecae
• Many are agriculturally important
• nitrogen fixers

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The ? (alpha) Proteobacteria

• Human pathogens
• Bartonella - Gram- bacillus
• Cat-scratch disease
• Brucella non-motile coccobacilli
• Brucellosis
• Obligate intracellular parasites
• Rickettsia Gram bacillus or coccobacilli
• Arthropod-borne cause spotted fevers
• R. prowazekii - Epidemic typhus (lice)
• R. typhi - Endemic murine typhus (fleas)
• R. rickettsii - Rocky Mountain Spotted Fever
  (ticks)

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The ? (alpha) Proteobacteria
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The ? (alpha) Proteobacteria

• Have prosthecae
• Caulobacter
• Stalked bacteria found in low nutrient aquatic
  environment
• Stalks increase surface area for nutrient uptake
• Hyphomicrobium
• Budding bacteria found in low nutrient
  environment

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The ? (alpha) Proteobacteria

• Nitrogen-fixing bacteria
• Azospirillum
• Grows in close association with the roots of
  tropical grasses and sugar cane
• Fix nitrogen for plant
• Rhizobium
• Fix nitrogen in the roots of plants
• Infect roots of legumes forming root nodules

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The ? (alpha) Proteobacteria

• Plant pathogen
• Agrobacterium
• Inserts a plasmid into plant cells, inducing a
  tumor
• Crown gall

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The ? (alpha) Proteobacteria

• Produce acetic acid from ethyl alcohol
• Acetobacter
• Gluconobacter
• Important commercially
• Nitrifying bacteria
• Oxidize nitrogen for energy
• Fix CO2 for carbon source
• Nitrobacter. NH4 ? NO2 (ammonium to nitrite)
• Nitrosomonas. NO2 ? NO3 (nitrite to nitrate)
• Agriculturally important

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The ? (alpha) Proteobacteria

• Wolbachia
• Most common infectious bacteria
• Live as endosymbionts in insects and other
  animals
• Greatly influence survival and reproduction of
  host
• Infected male not infected female no offspring

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The ? (beta) Proteobacteria

• Often use nutrients that diffuse away from areas
  of anaerobic decomposition of organic matter
• Can utilize hydrogen gas, ammonia, and methane
  for energy
• Several medically important pathogens are in this
  group

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The ? (beta) Proteobacteria

• Thiobacillus
• Chemoautotrophic, oxidize sulfur H2S ? SO42
• Zoogloea
• Slimy masses in aerobic sewage-treatment processes

• Sphaerotilus-
• - Chemoheterotophic,
• - form hollow filamentous
• sheaths
• - common in sewage

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The ? (beta) Proteobacteria

• Spirillum
• Chemoheterotrophic
• Helical with polar flagella
• Large, areobic
• Neisseria
• Chemoheterotrophic, cocci, aerobic
• N. meningitidis
• meningitis
• N. gonorrhoeae
• Gonorrhoea

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The ? (beta) Proteobacteria

• Bordetella
• Chemoheterotrophic, aerobic, rods
• B. pertussis - whooping cough
• Burkholderia
• Previously grouped with Pseudomonas
• Nosocomial infections
• Grow in disinfectant solutions
• Metabolize respiratory secretions in cystic
  fibrosis patients

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The ? (gamma) Proteobacteria

• Largest subgroup of the proteobacteria
• Great variety of physiological types
• Includes the enterics
• facultative anaerobic, G- rods that inhabit
  intestinal tract of animals

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The ? (gamma) Proteobacteria

• Beggiatoa
• Chemoautotrophic, oxidize H2S to S0 for energy
• Beggiatoa alba
• Francisella
• Chemoheterotrophic
• Francisella tularensis - tularemia

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The ? (gamma) Proteobacteria

• Pseudomonadales
• Pseudomonas
• Opportunistic pathogens
• Nosocomial infections
• Polar flagella
• Extra-cellular pigments
• Azotobacter and Azomonas
• Nitrogen fixing, soil bacteria
• Moraxella
• Moraxella lucunata
• Conjunctivitis

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The ? (gamma) Proteobacteria

• Legionellales
• Legionella
• Found in streams, warm-water pipes, cooling
  towers
• L. pneumophilia
• Causes a form of pneumonia called legionellosis
• Coxiella
• Coxiella burnetii
• Q fever transmitted via aerosols or milk
• Obligate intracellular pathogen

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The ? (gamma) Proteobacteria

• Vibrionales
• Facultative anaerobe
• curved rod or comma shape
• Found in coastal water
• Vibrio cholerae causes cholera
• V. parahaemolyticus causes gastroenteritis

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The ? (gamma) Proteobacteria

• Enterobacteriales (enterics)
• Peritrichous flagella, facultatively anaerobic,
  rods
• Inhabit intestinal tract of animals (humans)
• Escherichia
• Salmonella
• Shigella
• Klebsiella
• Serratia
• Proteus
• Yersinia
• Erwinia
• Enterobacter

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• Escherichia
• Coliforms fecal contamination
• UTI and Travelers Diarrhea
• Food posioning E. coli 0157H7
• Salmonella
• Salmonella enterica
• Salmonella enterica servor typhi typhoid fever
• Shigella
• Shigellosis (bacillary dysentery)

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• Klebsiella
• Klebsiella pneumoniae
• pneumonia
• Serratia
• Serratia marcescens
• Red pigments
• Proteus
• Swarmer cells
• UTI and wound infections

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• Yersinia
• Yersinia pestis - plague
• Enterobacter
• Enterobacter aerogenes and cloacae
• UTI and nosocomial infections
• Erwinia
• Plant pathogen

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The ? (gamma) Proteobacteria

• Pasteurellales
• Pasteurella
• Cause pneumonia and septicemia
• mainly pathogens of domestic animals
• can be passed to humans from cat and dog bites
• Pasteurella multocidia
• Haemophilus
• may inhabit mucous membranes of upper respiratory
  tract, mouth, vagina, and intestinal tract
• require blood (heme X factor) and the cofactor
  NAD (V factor)
• H. ducreyi
• H. influenzae does not cause the flu
• meningitis, pneumonia, bronchitis, septic
  arthritis, frequent cause of earaches in children

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The ? (delta) Proteobacteria

• Some species are predators on other bacteria
• Important contributors to the sulfur cycle

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The ? (delta) Proteobacteria

• Bdellovibrio
• Prey on other bacteria
• attack other gram (-) bacteria similar to the way
  a virus would
• Desulfovibrionales
• obligate anaerobe
• Use S instead of O2 as final electron acceptor
• Myxococcales
• Move by gliding, leave a slime trail
• Cells aggregate to form myxospores
• Most complex life cycle of all bacteria

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The ? (delta) Proteobacteria
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The ? (delta) Proteobacteria
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The ? (epsilon) Proteobacteria

• Slender gram (-) rods that are helical or
  vibrioid
• helical without a complete turn
• Motile by means of flagella
• Microaerophilic

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The ? (epsilon) Proteobacteria

• Campylobacter microaerophilic vibrio
• C. fetus can cause spontaneous abortion in
  domestic animals
• C. jejuni is a leading cause of outbreaks of food
  borne disease mainly transmitted by undercooked
  poultry
• Helicobacter microaerophilic vibrio
• H. pylori is the most common cause of stomach
  ulcers in humans