DESCRIPTION OF THE KINGDOM PIRELLAE AND ITS SINGLE PHYLUM PIRELLOBACTERIA (BOTH NAMES DERIVED FROM MARGULIS AND SCHWARTZ 1998)
| EUBACTERIA> PROTEOBACTERIAE> PIRELLAE> PIRELLOBACTERIA |
KINGDOM PIRELLAE LINKS
| Pirellae (pi-REL-e) is derived from Pirella, a common genus in the kingdom. |
| INTRODUCTION TO THE KINGDOM PIRELLAE AND ITS SINGLE PHYLUM, PIRELLOBACTERIA All free-living taxa are aerobic chemoheterotrophs. In addition, they are stalked and superficially similar to the prosthecate alphaproteobacteria (see Figure 1). The similarity disappears, however, when the organisms are examined in more detail. Their cell walls are made of protein rather than peptidoglycan, a synapomorphy that separates them from all other Eubacteria. Members of this group grow from the poles of the cell (polar growth) or by budding. Free-living taxa, referred to as the planctomycetes after Planctomyces (Figure 1), a common member of the plankton of lakes and ponds. Gemmata (Figure 2), another planctomycete, is spherical and occurs in many types of aquatic habitats, even sewage treatment ponds. However, it is highly unusual in that ultrastructural examination of the organism revealed that the nucleoid region was bound by a membrane (Wang et al. 2002). The other major group in this phylum is the parasitic taxon, Chlamydiae. The chlamydias are highly reduced coccoid intracellular parasites (0.2-0.7 µm in diameter; see Figure 2). The have a highly reduced genome and seem to be unable to make their own ATP, relying on the biochemical machinery of the host cell to make it for them. They cause diseases of human beings that do not require arthropod vectors. One such disease is trachoma, which is common in developing countries and a leading cause of female reproductive problems in the US. Other species cause psittacosis and a chlamydial pneumonia. These taxa were once grouped with the other stalked bacteria; however, the Pirellobacteria were separated on the basis of their 16S rRNA. The defining synapomorphy is the type of cell covering. Members of this group are united in having a proteinaceous wall instead of one made of peptidoglycan. We follow the system of Margulis and Schwartz (1998) in which these taxa are grouped together in a single phylum is designated B-11. We have separated the free-living and parasitic taxa into separate classes. Bergey’s Manual of Systematic Bacteriology, 2nd edition (Garrity et al. 2001) treats the taxa that we include in the Pirellae as two phyla (Planctomycetes and Chlamydiae) of Bacteria. The taxa in this system (see Figure 4), which is based on Margulis and Schwartz (1998) with modifications from Garrity et al. (2001, 2003, and 2005), Tudge (2000), and Black (2002), corresponds to the clade Verrucomicrobia + Lentisphaerae + Chlamydiae + Planctomycetes (see Figure 5) of the All Species Living Tree Project (Yarza et al. 2008 and 2010; Munoz et al. 2011). These taxa appear to be among the crown taxa in the Eubacteria. |
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| FIGURE 1. Planctomyces, a common free-floating prosthecate bacterium in lakes and ponds. Image from http://biol-zukan.nara-edu.ac.jp/CompressedPict/Keiso/KeisoHoshi.JPG | FIGURE 2. A TEM micrograph of Gemmata showing the membrane-bound nucleoid region. Image from Figure 1C of Wang et al. (2002) | FIGURE 3. Chlamydia, a very small obligate intracellular parasite of humans and other vertebrates. The bacteria are growing within some of the cultured cells and appear to be stipples inside the infected cells. Image from http://www.bmb.leeds.ac.uk/mbiology/ug/ugteach/icu8/images/std/chlamydia.jpg |
FIGURE 4. This tree uses Margulis and Schwartz (1998), with modifications from Garrity et al. (2001, 2003, and 2005), Tudge (2000), and Black (2002) in its structure. Note that it differs significantly from Figure 5, a tree generated by the All Species Living Tree Project.
FIGURE 5. A simplified summary tree for the Eubacteria adapted from the All Species Living Tree Project (Yarza et al. 2008 and 2010; Munoz et al. 2011). Note that the position of the taxa in this group (the clade that includes Verrucomicrobia + Lentisphaerae + Chlamydiae + Planctomycetes).
| FURTHER READING: DISCOVERY OF THE DOMAINS OF LIFE INTRODUCTION TO THE DOMAIN EUKARYA DESCRIPTION OF THE DOMAIN ARCHAEA |
| LITERATURE CITED Barnes, R. S. K. 1984b. Kingdom Monera. IN: Barnes, R.S.K., ed. A synoptic classification of living organisms. Sinauer Associates. Sunderland, Mass. 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. 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. 1998. Five kingdoms, an illustrated guide to the phyla of life on earth. 3rd Edition. W. H. Freeman and Co. New York. 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. Wang, J., C. Jenkins, R. I. Webb, and J. A. Fuerst. 2002. Isolation of Gemmata-like and Isosphaera-like planctomycete bacteria from soil and freshwater. Applied and Environmental Microbiology. 68(1): 417-422. |
| By Jack R. Holt. Last revised: 02/07/2013 |
