ALPHAPROTEOBACTERIA
Danielle Miller
Madison Klug
PHYLUM PROTEOBACTERIA
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Includes most of the gram
negative
chemoheterotrophic bacteria
Presumed to have arisen
from a common
photosynthetic ancestor
Largest taxonomic group of
bacteria
Few are now
photosynthetic- other
metabolic and nutritional
capacities have arisen to
replace this characteristic
Name “Proteobacteria”
taken from the mythological
Greek god Proteus, who
could assume many shapes
PROTEOBACTERIA CLASSES
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Proteobacteria are separated into five classes
designated by Greek letters:
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Alphaproteobacteria
Betaproteobacteria
Gammaproteobacteria
Deltaproteobacteria
Epsilonproteobacteria
OVERVIEW
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Proteobacteria
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Alphaproteobacteria
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Caulobacterales
Rickettisiales
 Rickettsia
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Ehrlichia
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Ehrlichiosis
Rhizobiales
 Bartonella
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Cat Scratch Disease
Brucella
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Epidemic Typhus
Rocky Mountain Spotted Fever
Brucellosis
Rhodospirillales
Betaproteobacteria
Gammaproteobacteria
 Deltaproteobacteria
 Epsilonproteobacteria
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ALPHAPROTEOBACTERIA
Gram Negative
 Adopt an intracellular life-style
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Plant mutualists
 Plant and animal pathogens
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Contains most of the proteobacteria that are
capable of growth at very low levels of nutrients.
 Most abundant of marine cellular organisms
 Variety of metabolic strategies:

 Photosynthesis
 Nitrogen
Fixation
 Ammonia
oxidation
 Methylotrophy
ALPHAPROTEOBACTERIA
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Morphologies:
Stellate
 Spiral
 Prosthecae
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Ancestral group for
mitochondria
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Rickettsiales
DICHOTOMOUS KEY
ALPHAPROTEOBACTERIA
Order
Important Genera
Special Features
Caulobacterales
Caulobacter
Stalked
Rickettsiales
-Ehrlichia
-Rickettsia
-Wolbachia
-Obligately intracellular human pathogens.
-Obligately intracellular human pathogens.
-Symbionts of insects.
Rhizobiales
-Agrobacterium
-Bartonella
-Beijerinckia
-Bradyrhizobium
-Brucella
-Hyphomicrobium
-Nitrobacter
-Rhizobium
-Plant pathogens.
-Human pathogens.
-Free-living nitrogen fixers.
-Symbiotic nitrogen fixers.
-Human Pathogens.
-Budding
-Nitrifying
-Symbiotic nitrogen fixers
Rhodospirllales
-Acetobacter
-Azospirillum
-Gluconobacter
-Rhodospirillum
-Acetic acid producers.
-Nitrogen fixers.
-Acetic acid producers.
-Photosynthetic, anoxygenic.
ORDER CAULOBACTERALES
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Found in low nutrient
aquatic environments,
such as lakes
Feature stalks that
anchor the organisms to
surfaces
Increases their nutrient
uptake because they are
exposed to a
continuously changing
flow of water
 Can use the host’s
excretions as nutrients
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ORDER RICKETTSIALES- GENUS RICKETTSIA
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Gram-negative rod shaped
bacteria
Enter their host cell by inducing
phagocytosis
 They quickly enter the
cytoplasm of the cell and
begin reproducing by binary
fission
 Survival depends on entry,
growth and replication within
the cytoplasm of eukaryotic
host cells
Thought to be the closest living
relatives that were the origin of
the mitochondria organelles
ORDER RICKETTSIALES- GENUS RICKETTSIA
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Obligate intracellular
parasites- they reproduce
only within a mammalian
cell
Can only grow in tissue
cultures or embryos
Infections damage the
permeability of blood
capillaries, which results
in a characteristic spotted
rash
Two clinical groups:
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Typhus Group
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Spotted Fever Group
EPIDEMIC TYPHUS (TYPHUS GROUP)
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Caused by Rickettsia
prowazekii
Transmitted by human
body lice and the
ectoparasites of flying
squirrels
R. prowazekii grows in the
louse's gut and is excreted
in its feces.
 The disease is then
transmitted to an
uninfected human who
scratches the louse bite
and rubs the feces into
the wound.
EPIDEMIC TYPHUS (TYPHUS GROUP)
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Occurs in communities and
populations where body lice are
prevalent
Outbreaks have often been tied to
periods of war, poverty, and
natural disasters, especially
during the colder months when
infested clothing is not laundered
Symptoms:
 Headache, chills, fever,
confusion, rash, photophobia.
 Rash begins on the chest
about five days after the fever
appears, and spreads.
Treatment: antibiotics
 Infection can also be
prevented with vaccination
ROCKY MOUNTAIN SPOTTED FEVER
(SPOTTED FEVER GROUP)
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Caused by Rickettsia
rickettsii
Most lethal and most
frequent of the Spotted
Fever diseases
Transmitted by the
American Dog Tick, Brown
Dog Tick and the Rocky
Mountain Wood Tick
 They serve as both
reservoirs and vectors
of the disease
 Transmitted through
saliva while the tick is
feeding on the blood of
the host
ROCKY MOUNTAIN SPOTTED FEVER
(SPOTTED FEVER GROUP)
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Symptoms:
 Fever, headache,
nausea, muscular pain
and a severe rash that
develops 2-3 days after
the onset of fever
Treatment:
 Antibiotic treatment
needed immediatelyDoxycycline (most
effective when started
before the 5th day of
onset)
 More severe cases may
require longer periods
of antibiotic treatment
ORDER RICKETTSIALES-GENUS EHRLICHIA
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Gram-negative,
rickettsia-like bacteria
Live obligately within
white blood cells
Ehrlichia species are
transmitted by ticks to
humans and cause
ehrlichiosis
 the general name
used to describe
several bacterial
diseases that affect
animals and humans
EHRLICHIOSIS
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Human ehrlichiosis:
 caused by at least three
different ehrlichial
species in the United
States:
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Ehrlichia chaffeensis
Ehrlichia ewingii
Ehrlichia muris-like
Ehrlichiae are transmitted
to humans by the bite of
an infected tick.
The lone star tick is the
primary vector of both
Ehrlichia chaffeensis and
Ehrlichia ewingii
EHRLICHIOSIS
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Symptoms:
 fever, headache, fatigue, and muscle aches.
 symptoms occur within 1-2 weeks following a tick bite
 Skin rash is not considered a common feature of
ehrlichiosis, and should not be used to rule in or rule out
an infection
 Some patients may develop a rash that resembles the
rash of Rocky Mountain spotted fever making these two
diseases difficult to differentiate on the basis of clinical
signs alone
Treatment: doxycycline
 Antibiotic treatment
 in a class of medications called tetracycline antibiotics
 It works by preventing the growth and spread of
bacteria.
ORDER RHIZOBIALES
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Variety of strategies to
adapt and exploit niches.
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Capable of fixing nitrogen
in symbiosis with
leguminous plants
Obligate and facultative
intracellular bacteria and
plant and animal
pathogens.
 Clinical Genera:
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Bartonella
 Brucella
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GENUS BARTONELLA
Gram-negative bacillus
 Bartonella henselae Aka: Cat Scratch Disease (CSD)
 Vector: Cat
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Show no sign
Transmission: scratches, bites, saliva
 At point of injury a mild infection occurs.
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CAT SCRATCH DISEASE
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Symptoms:
Lymph node swelling near site
of bite or scratch.
 Can create a tunnel through
the skin and leak fluid.
 Headache, fever, fatigue, etc.
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Treatments:
Usually not needed.
 Antibiotics, like azithromycin
can be helpful.
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GENUS BRUCELLA
Small, non-motile
coccobacilli
 Obligate parasites of
mammals
 Ability to survive
phagocytosis.
 Usually passed around
animals, causing disease
in many different
vertebrates
 Cause the disease
brucellosis
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BRUCELLOSIS
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Route of Transmission:
 GI track
 Respiration
 Skin wounds
Disease Symptoms:
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Fever, sweats, headaches, back pains, and physical
weakness.
Severe infections of the central nervous systems or
lining of the heart may occur.
Treatments:
 Usually, doxycycline and rifampin are used in
combination for 6 weeks to prevent reoccurring
infection.
 Depending on the timing of treatment and severity
of illness, recovery may take a few weeks to several
months.
ORDER RHODOSPIRILLALES
RHODOSPIRILLALES
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Azospirillum:
Soil bacteria
 Uses nutrients excreted by plants and in return fixes
nitrogen from the atmosphere.
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Acetobacter and Gluconobacter:
Industrially important aerobic organisms
 Convert EtOH into acetic acid (Vinegar)
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Rhodospirillum:
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Photosynthetic
REFERENCES
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http://www.cdc.gov/rmsf/
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http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002581/
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http://www.cdc.gov/healthypets/diseases/catscratch.htm
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http://wwwnc.cdc.gov/travel/yellowbook/2010/chapter-5/rickettsial-and-related-infections.aspx
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http://www.cdc.gov/Ehrlichiosis/symptoms/index.html
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http://www.cdc.gov/ncidod/dbmd/diseaseinfo/brucellosis_g.htm
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http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000563/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1913456/#__sec17

Carvalho, F., Souza, R., Barcellos, F., Hungria, M., & Vasconcelos, A. (2010). Genomic and
evolutionary comparisons of diazotrophic and pathogenic bacteria of the order Rhizobiales. BMC
Microbiology, 101-15. doi:10.1186/1471-2180-10-37

http://permaculturetokyo.blogspot.com/2009/02/rhizobium-symbiosis-with-woody-plants.html
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http://www.nlm.nih.gov/medlineplus/ency/article/001614.htm
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http://www.cdc.gov/ncidod/dbmd/diseaseinfo/brucellosis_g.htm

http://medconditions.net/rhodospirillales.html

Tortora, Gerard J., Berdell R. Funke, and Christine L. Case. Microbiology: an Introduction. San
Francisco, CA: Pearson Benjamin Cummings, 2010.