ALPHAPROTEOBACTERIADanielle Miller

Madison Klug

PHYLUM PROTEOBACTERIA 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

Proteobacteria are separated into five classes designated by Greek letters: Alphaproteobacteria Betaproteobacteria Gammaproteobacteria Deltaproteobacteria Epsilonproteobacteria

OVERVIEW Proteobacteria

Alphaproteobacteria Caulobacterales Rickettisiales

Rickettsia Epidemic Typhus Rocky Mountain Spotted Fever

Ehrlichia Ehrlichiosis

Rhizobiales Bartonella

Cat Scratch Disease Brucella

Brucellosis Rhodospirillales

Betaproteobacteria Gammaproteobacteria Deltaproteobacteria Epsilonproteobacteria

ALPHAPROTEOBACTERIA

Gram Negative Adopt an intracellular life-style

Plant mutualists Plant and animal pathogens 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

Morphologies: Stellate Spiral Prosthecae

Ancestral group for mitochondria Rickettsiales

DICHOTOMOUS KEY

ALPHAPROTEOBACTERIAOrder 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

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

ORDER RICKETTSIALES- GENUS RICKETTSIA

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

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: Typhus Group Spotted Fever Group

EPIDEMIC TYPHUS (TYPHUS GROUP) 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) 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) 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)

Symptoms: Fever, headache,

nausea, muscular pain and a severe rash that develops 2-3 days after the onset of fever

Treatment: Antibiotic treatment

needed immediately- Doxycycline (most effective when started before the 5th day of onset)

More severe cases may require longer periods of antibiotic treatment

ORDER RICKETTSIALES-GENUS EHRLICHIA

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 Human ehrlichiosis:

caused by at least three different ehrlichial species in the United States: 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 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

Variety of strategies to adapt and exploit niches. Capable of fixing

nitrogen in symbiosis with leguminous plants

Obligate and facultative intracellular bacteria and plant and animal pathogens.

Clinical Genera: Bartonella Brucella

GENUS BARTONELLA

Gram-negative bacillus Bartonella henselae Aka: Cat Scratch Disease

(CSD) Vector: Cat

Show no sign Transmission: scratches, bites, saliva At point of injury a mild infection occurs.

CAT SCRATCH DISEASE

Symptoms: Lymph node swelling near

site of bite or scratch. Can create a tunnel through

the skin and leak fluid. Headache, fever, fatigue,

etc. Treatments:

Usually not needed. Antibiotics, like azithromycin

can be helpful.

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

BRUCELLOSIS Route of Transmission:

GI track Respiration Skin wounds

Disease Symptoms: 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

Azospirillum: Soil bacteria Uses nutrients excreted by plants and in return

fixes nitrogen from the atmosphere. Acetobacter and Gluconobacter:

Industrially important aerobic organisms Convert EtOH into acetic acid (Vinegar)

Rhodospirillum: Photosynthetic

REFERENCES http://www.cdc.gov/rmsf/

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002581/

http://www.cdc.gov/healthypets/diseases/catscratch.htm

http://wwwnc.cdc.gov/travel/yellowbook/2010/chapter-5/rickettsial-and-related-infections.aspx

http://www.cdc.gov/Ehrlichiosis/symptoms/index.html

http://www.cdc.gov/ncidod/dbmd/diseaseinfo/brucellosis_g.htm

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

http://www.nlm.nih.gov/medlineplus/ency/article/001614.htm

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.