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Prokaryotes: Domains of
Archaea and Bacteria
Proteobacteria
What are the general characteristics of proteobacteria?
Domain:Eubacteria; Phylum: Proteobacteria
named after Proteus (greek god of sea, takes many forms,
proteobacteria have many forms)
Prokaryote
Cell wall: Gram-negative, LPS outer membrane
Mostly unicellular, can form cellular aggregates
Motility: flagella, non-motile or gliding
Metabolism:
most facultative/obligate anaerobic
most chemoheterotrophic or chemoautotrophic
Reproduction: binary fission
Based on rRNA sequences what are the different classes of proteobacteria?
Prokaryotes: Domains of Archaea and Bacteria 1
, Alphaproteobacteria
What are the basic characteristics?
Prokaryotic
Cell wall: Gram-negative
Metabolism: Oligotrophic (able to survive in low-nutrient env)
Got most phototrophic bacteria
What are the different genera?
1. Caulobacter spp
a. Habitat: Aquatic
b. Shape: Bacillus, prosthecae, swarm or stalk cells
c. Motility: Polar Flagella
d. Metabolism:
i. Chemoautotrophic, sulfur oxidizing (H2S or S to SO4 2-)
ii. Obligatory Aerobic
e. Non-pathogenic
f. example: Caulobacter crescentus
2. Acetobacter sp, Gluconobacter sp
a. Shape: Bacillus
b. Motility: non-motile
c. Metabolism: can convert ethanol to acetic acid, obligatory
aerobic
d. example: Acetobacter aceti,
3. Methylobacterium sp
a. Shape: Bacillus
b. Motility: depends on species, flagella
c. Metabolism: Metabolize C1 (CH4), facultative aerobe
d. example: Methylobacterium aquaticum
4. Rhizobium sp
Prokaryotes: Domains of Archaea and Bacteria 2
, a. Metabolism: Nitrogen Fixing (N2 to methane) in association
with plant roots (legume symbionts)
b. Pathogenic:
i. Rhizobium radiobacter or Agrobacterium tumafaciens
causes crown gall; doesn’t harm humans, plasmid (Ti
plasmid) studied to DNA transfer vesicle (gene
engineering)
c. Other nitrogen fixing genus: Bradyrhizobium sp, Azospirillum
sp, Lipoferum sp
5. Nitrobacter sp (both aerobic)
a. Nitrifiying bacteria
6. Candidatus Pelagibacter spp (ubique)
a. microbial plankton cells helps deep sea algae
b. Pathogenic
7. Rickettsia sp
a. General Characteristics:
i. zoonotic, aerobic, obligate intracellular parasite, G-ve,
bacillus or coccobacilli, highly pleomorphic, non-spore-
forming, motile (actin-based).
ii. Mode of transmission: Indirect via Vector-borne (ticks,
body lice, mites, fleas ex lone star tick)
iii. infect endothelial tissue trigger phagocytosis and lives in
cell
iv. Characteristic of infection (human):
1. incubation: 5-10 days, symptoms 1-2 weeks
2. (influenza like symptoms) fever, headache, myalgia,
nausea, petechial rash or eschar at bite site
v. Examples:
1. Rocky mountain spotted fever : R. ricketsii
2. epidemic typhus: R. prowazeskii
Prokaryotes: Domains of Archaea and Bacteria 3
Prokaryotes: Domains of
Archaea and Bacteria
Proteobacteria
What are the general characteristics of proteobacteria?
Domain:Eubacteria; Phylum: Proteobacteria
named after Proteus (greek god of sea, takes many forms,
proteobacteria have many forms)
Prokaryote
Cell wall: Gram-negative, LPS outer membrane
Mostly unicellular, can form cellular aggregates
Motility: flagella, non-motile or gliding
Metabolism:
most facultative/obligate anaerobic
most chemoheterotrophic or chemoautotrophic
Reproduction: binary fission
Based on rRNA sequences what are the different classes of proteobacteria?
Prokaryotes: Domains of Archaea and Bacteria 1
, Alphaproteobacteria
What are the basic characteristics?
Prokaryotic
Cell wall: Gram-negative
Metabolism: Oligotrophic (able to survive in low-nutrient env)
Got most phototrophic bacteria
What are the different genera?
1. Caulobacter spp
a. Habitat: Aquatic
b. Shape: Bacillus, prosthecae, swarm or stalk cells
c. Motility: Polar Flagella
d. Metabolism:
i. Chemoautotrophic, sulfur oxidizing (H2S or S to SO4 2-)
ii. Obligatory Aerobic
e. Non-pathogenic
f. example: Caulobacter crescentus
2. Acetobacter sp, Gluconobacter sp
a. Shape: Bacillus
b. Motility: non-motile
c. Metabolism: can convert ethanol to acetic acid, obligatory
aerobic
d. example: Acetobacter aceti,
3. Methylobacterium sp
a. Shape: Bacillus
b. Motility: depends on species, flagella
c. Metabolism: Metabolize C1 (CH4), facultative aerobe
d. example: Methylobacterium aquaticum
4. Rhizobium sp
Prokaryotes: Domains of Archaea and Bacteria 2
, a. Metabolism: Nitrogen Fixing (N2 to methane) in association
with plant roots (legume symbionts)
b. Pathogenic:
i. Rhizobium radiobacter or Agrobacterium tumafaciens
causes crown gall; doesn’t harm humans, plasmid (Ti
plasmid) studied to DNA transfer vesicle (gene
engineering)
c. Other nitrogen fixing genus: Bradyrhizobium sp, Azospirillum
sp, Lipoferum sp
5. Nitrobacter sp (both aerobic)
a. Nitrifiying bacteria
6. Candidatus Pelagibacter spp (ubique)
a. microbial plankton cells helps deep sea algae
b. Pathogenic
7. Rickettsia sp
a. General Characteristics:
i. zoonotic, aerobic, obligate intracellular parasite, G-ve,
bacillus or coccobacilli, highly pleomorphic, non-spore-
forming, motile (actin-based).
ii. Mode of transmission: Indirect via Vector-borne (ticks,
body lice, mites, fleas ex lone star tick)
iii. infect endothelial tissue trigger phagocytosis and lives in
cell
iv. Characteristic of infection (human):
1. incubation: 5-10 days, symptoms 1-2 weeks
2. (influenza like symptoms) fever, headache, myalgia,
nausea, petechial rash or eschar at bite site
v. Examples:
1. Rocky mountain spotted fever : R. ricketsii
2. epidemic typhus: R. prowazeskii
Prokaryotes: Domains of Archaea and Bacteria 3
