Alphaproteobacteria

1. Alphaproteobacteria Danielle Miller Madison Klug

2. 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

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

4. 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

5. 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

6. Alphaproteobacteria • Morphologies: • Stellate • Spiral • Prosthecae • Ancestral group for mitochondria • Rickettsiales

7. Dichotomous Key

8. Alphaproteobacteria

9. 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

10. 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

11. 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

12. 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.

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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.

19. 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

20. 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.

21. 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.

22. 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

23. 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.

24. Order Rhodospirillales

25. 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

26. 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.