DESCRIPTION OF THE PHYLUM DELTAPROTEOBACTERIA (STACKENBRANDT ET AL. 1988)
| EUBACTERIA> PROTEOBACTERIAE> DELTAPROTEOBACTERIA |
PHYLUM DELTAPROTEOBACTERIA LINKS
| Deltaproteobacteria (del-tuh-PRO-te-o-bak-TE-re-uh) is derived from two Greek roots and a Greek letter meaning “delta” (δ) “changeable” (proteakos -πρωτεϊκός) “little stick” (bakterion -βακτήριον). The name is in reference to Proteus, the name of a Greek sea god who could change his shape (Stackebrandt et al. 1988). |
| INTRODUCTION TO THE DELTAPROTEOBACTERIA These organisms are formed by two major, and very different groups. One group tends to be unicellular and obligate anaerobes. Most of them use sulfate as the terminal electron acceptor and reduce it to sulfide. They occur in association with anoxic, sulfur-rich mud, geothermal springs, and digestive tracts. Geobacter (see Figure 1), first isolated from mud in the Potomac River, can pass off its electrons to metals, so NASA is testing it to see if it can be used to make a living battery that gets its energy through organic waste. The other major clade is made of obligate aerobes (there are no known facultatively anaerobic taxa in this phylum). The bdellovibrios are predatory cells that feed on other bacteria (Figure 2). They have a polar, sheathed flagellum, which allows them to swim at speeds up to 100 cell-lengths per second in their attack phase. After attaching to a bacterial cell, a bdellovibrio enters the intraperiplasmic space where they feed on the host and then reproduce. The gliding bacteria live in the vegetative state as gliding rods embedded in a polysaccharide slime. At some cue, they begin to aggregate and form a multicellular structure, which forms a fruiting body. Cells in the fruiting body, called a myxosporangium (Figure 3), form desiccation-resistant cells that serve as spores (called myxospores). The myxospores may function in dispersal, but likely they function primarily as resting spores. Stackebrandt et al. (1988), using 16S rRNA sequences, defined a seemingly unrelated group of eubacteria as Proteobacteria, the purple bacteria, which they defined as a class that they called Proteobacteria. Within that group, they defined five separate lines, each defined by a Greek letter: α, β, γ, δ, ε. The second edition of Bergey’s Manual of Systematic Bacteriology (Garrity et al. 2003) adopted Proteobacteria, but raised it to phylum level with each of the five groups becoming classes. In order to bring the prokaryotes into line with kingdom-level divisions in the eukaryotes, we felt that it was necessary to raise the Proteobacteria to kingdom-level status with each of the five groups also raised to the level of phylum. |
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| FIGURE 1. TEM micrograph of Geobacter. Image from NASA and in the Public Domain | FIGURE 2. TEM micrograph of Bdellovibrio attacking a host bacterial cell. Image from http://microgen.ouhsc.edu/b_bacter/fig1.png | FIGURE 3. SEM micrograph of Stigmatella forming myxosporangia. Image from http://www.zmbh.uni-heidelberg.de/Schairer/2.JPG |
FIGURE 4. Topology of the Proteobacteria with the relationships of the phyla and classes of the Deltaproteobacteria (in shaded box).
| 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: 09/05/2016 |
