A LPHAPROTEOBACTERIA Danielle Miller Madison Klug

P HYLUM P ROTEOBACTERIA 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

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

O VERVIEW 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

A LPHAPROTEOBACTERIA 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

A LPHAPROTEOBACTERIA Morphologies: Stellate Spiral Prosthecae Ancestral group for mitochondria Rickettsiales

D ICHOTOMOUS K EY

A LPHAPROTEOBACTERIA OrderImportant GeneraSpecial Features CaulobacteralesCaulobacterStalked Rickettsiales -Ehrlichia -Rickettsia -Wolbachia -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.

O RDER C AULOBACTERALES 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

O RDER R ICKETTSIALES - G ENUS R ICKETTSIA 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

O RDER R ICKETTSIALES - G ENUS R ICKETTSIA 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

E PIDEMIC TYPHUS (T YPHUS G ROUP ) 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.

E PIDEMIC TYPHUS (T YPHUS G ROUP ) 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

R OCKY M OUNTAIN S POTTED F EVER (S POTTED F EVER G ROUP ) 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

R OCKY M OUNTAIN S POTTED F EVER (S POTTED F EVER G ROUP ) 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 5 th day of onset) More severe cases may require longer periods of antibiotic treatment

O RDER R ICKETTSIALES -G ENUS E HRLICHIA 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

E HRLICHIOSIS 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

E HRLICHIOSIS 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.

O RDER R HIZOBIALES 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

G ENUS B ARTONELLA 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.

C AT S CRATCH D ISEASE 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.

G ENUS B RUCELLA 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

B RUCELLOSIS 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.

O RDER R HODOSPIRILLALES

R HODOSPIRILLALES 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

R EFERENCES 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, doi: / Tortora, Gerard J., Berdell R. Funke, and Christine L. Case. Microbiology: an Introduction. San Francisco, CA: Pearson Benjamin Cummings, 2010.