SYNOPTIC DESCRIPTION OF THE PHYLUM ALPHAPROTEOBACTERIA (STACKENBRANDT ET AL. 1988)
| EUBACTERIA> PROTEOBACTERIAE> ALPHAPROTEOBACTERIA |
PHYLUM ALPHAPROTEOBACTERIA LINKS
| The following description comes mainly from Margulis and Schwartz (1998), Barnes (1984), Brock et al. (1994), and Tudge (2000). |
- I. SYNONYMS: α-proteobacteria, rickettsias, purple nonsulfur bacteria, nitrogen-fixing bacteria, and nodule-forming bacteria.
- II. PHYLUM CHARACTERISTICS
- A. Structure
- Cell Form: Unicellular rods (text with tooltip) A rod is an elongate cell form such that it has distinct ends (called poles). , cocci (text with tooltip) A coccus (cocci, pl.) is a spherical cell form. , spirals (text with tooltip) A spiral is a cell form that is a cork-screw shaped rod. ; and filaments (text with tooltip) A filament is a linear array of cells. In the Cyanobacteria, a filament is the linear array of cells (trichome) plus the surrounding mucilaginous sheath. .
- Cell Wall: Gram- (text with tooltip) A Gram - cell loses the blue-black crystal-violet color following destaining with alcohol during the Gram Stain procedure. Then, it takes on the color of the counterstain, typically iodine. .
- Motility (text with tooltip) Etymology: Motile comes from the Latin, motus, a participle of the verb movere, which means to move. Although the Latin word means general movement, the Biological term means a cell or colony of cells that move by means of flagella. : Non-motile or motile with polar (text with tooltip) Polar flagella are those that emerge from the poles of the cell (rods or spirals). or peritrichous flagella (text with tooltip) Peritrichous flagella are inserted on the sides but not on the end of a rod or spiral cell. .
- B. Physiology
- O2 Tolerance: Aerobes (text with tooltip) Aerobes is derived from Greek terms aero (air) and bios (life). Aerobes (n) are those bacteria that require free oxygen for metabolism. and facultative anaerobes.
- Substrates: Rickettsias have limited metabolic ability and rely on the host cell. The purple nonsulfur bacteria are very diverse chemoorganotrophs (text with tooltip) Chemoorganotrophs utilize organic sources for energy and food production. , chemolithotrophs (text with tooltip) Chemolithotrophs are autotrophs (make their own food) by using inorganic sources for energy and reducing power to fix carbon dioxide into food. , photoautotrophs (text with tooltip) Phototrophs utilize light energy to provide metabolic energy. Sometimes this energy is stored asreduced organic compounds (food). , and some as methylotrophs. Rhizobias fix molecular nitrogen (text with tooltip) Nitrogen fixation is the ability to use energy to take nitrogen gas and reduce it to ammonium, nitrite, or nitrate. The initial step requires a nitrogenase enzyme and the energy of about 38 ATP molecules to fix one nitrogen molecule. by oxidation of small organic compounds such as ethanol, succinate, malate, fumerate, pyruvate, etc.
- Products: Rickettsias: have limited metabolic ability and rely on the host cell. Purple nonsulfur bacteria: produce food (or reduced organic carbon). Rhizobias: Ammonium; (text with tooltip) tipso symbiotic{/tipso] species release glutamine and other N-rich compounds to their host plant.
- C. Other: Very diverse group of bacteria.
- D. Ecology: Enter into parasitic (rickettsias), commensal, or mutualistic (many rhizobias) symbiotic relationships. Free-living taxa free-living in soil and aquatic systems.
- A. Structure
| LITERATURE CITED Black, J. G. 2002. Microbiology, Principles and Explorations. 5th ed. John Wiley and Sons, Inc. New York. Brock, T. D., M.T. Madigan, J.M. Martinko, and J. Parker. 1994. Biology of Microorganisms. 7th ed. Prentice Hall. Englewood Cliffs, NJ. Emerson, D., J. A. Rentz, T. G. Lilburn, R. E. Davis, H. Aldrich, C. Chan, and C. L. Moyer. 2007. A novel lineage of Proteobacteria involved in formation of marine Fe-oxidizing microbial mat communities. PLoS ONE. 2007 (8): e667. http://www.plosone.org Gao, B. and R. S. Gupta. 2007. Phylogenetic analysis of proteins that are distinctive of Archaea and its main subgroups and the origin of methanogenesis. BMC Genomics. 8:86. http://www.biomedcentral.com/1471-2164/8/86. Garrity, G. M., M. Winters, and D. Searles. 2001. Bergey’s manual of systematic bacteriology. 2nd ed. Springer-Verlag. New York. Garrity, G. M., J. A. Bell, and T. G. Lilburn. 2003. Taxonomic Outline of the Prokaryotes. Bergey’s Manual of Systematic Bacteriology. 2nd edition. Release 4.0. Springer-Verlag. New York. pp. 1-397. Margulis, L. and K. Schwartz. 1988. Five kingdoms, an illustrated guide to the phyla of life on earth. 2nd Edition. W. H. Freeman and Co. New York. Margulis, L. and K. Schwartz. 1998. Five kingdoms, an illustrated guide to the phyla of life on earth. 3rd Edition. W. H. Freeman and Co. New York. Stackebrandt, E., R. G. E. Murray, and H. G. Trüper. 1988. Proteobacteria classis nov., a name for the phylogenetic taxon that includes the “Purple Bacteria and Their Relatives”. International Journal of Systematic Bacteriology. 38(3): 321-325. Tudge, C. 2000. The Variety of Life, A Survey and a Celebration of all the Creatures That Have Ever Lived. Oxford University Press. New York. Williams, K. P., B. W. Sobral, and A. W. Dickerman. 2007. A robust species tree for the Alphaproteobacteria. Journal of Bacteriology. 189(13): 4578-4586. Woese, C. R. and G. E. Fox. 1977. Phylogenetic structure of the prokaryotic domain: the primary kingdoms. Proceedings of the National Academy of Sciences USA. 74:5088-5090. Woese, C. R., O. Kandler, and M. L. Wheelis. 1990. Towards a natural system of organisms: Proposal for the domains Archaea, Bacteria, and Eucarya. Proc. Natl. Acad. Sci. USA. 87: 4576-4579. |
| By Jack R. Holt. Last revised: 02/18/2013 |
