DESCRIPTION OF THE KINGDOM SPIROCHAETAE (EHRENBERG 1855) AND ITS SINGLE PHYLUM SPIROCHAETOBACTERIA
| EUBACTERIA> PROTEOBACTERIAE> SPIROCHAETAE> SPIROCHAETOBACTERIA |
KINGDOM SPIROCHAETAES LINKS
| Spirochaetae (spi-ro-KE-te) is derived from a Latin root meaning spiraled or coiled (spira) and a Greek root meaning long hair or mane (khaite -χαίτη). The name is descriptive of the group and refers to the long hair-like spiraled cells of this group. |
| INTRODUCTION TO THE SPIROCHAETAE AND ITS SINGLE PHYLUM, SPIROCHAETOBACTERIA The spirochaetes tend to be elongate and spiral with many polar flagella (text with tooltip) Polar flagella are those that emerge from the poles of the cell (rods or spirals). that are confined within the outer membrane and wind down the cell from both ends. The cross section of Treponema (Figure 1) illustrates the relationship between outer envelope, the inner membrane, and the confined polar flagella, which could number more than 200. This architecture causes the cell to have a characteristic cork-screw shape (Figure 2). A spirochaete cell moves by turning itself about its axis, thereby moving through the water in the same way that a screw moves through wood. This mode of movement is possible because at their scale, water is as dense as thick honey. The structure of the spirochaete cell and the way it moved suggested to Lynn Margulis (e.g. Margulis 1993, and Margulis et al. 2000) that the spirochaete might have been the bacterial symbiont that formed the eukaryotic flagellum (a structure that she called the undulapodium). For support of her assertion, she pointed out that the “cilia” that cover a eukaryotic trichomonad called Mixotricha paradoxa (Figure 3) are actually spirochaetes that attach to the outside of the cell and move in coordinated motion (first described by Cleveland and Grimstone . In fact, Margulis et al. (2000) argued that the merger of an archaean and a spirochaete gave rise to the nucleus and, thereby, the eukaryotic cell. Confirmation of the Margulis theory has not been forthcoming, though. No genes that bear the spirochete signature have been recovered from the genome of a eukaryote. Many taxa of spirochaetes are free-living, usually associated with organic-rich sediment in freshwater and marine habitats as well as microbial mats. They can also occur in extreme environments. For example, Hoover et al. (2003) report the occurrence of Spirochaeta americana in the anaerobic mud of highly alkaline Mono Lake in California (Figure 4). They have also been reported from oil field mud (Magot et al. 1997). Most taxa are obligate anaerobes, regardless of the environment. Those spirochetes that are most well known are of public health concern. Spirochetes cause leptospirosis (Leptospira), Lyme disease (Borrelia burgdorferi), relapsing fever (Borrelia recurrentis), siphilis (Treponema pallidum, Figure 5), and yaws (Treponema pertenue). They also live as commensals in the rumens of ungulates and the guts of wood-eating insects (e.g. termites). The Spirochaetobacteria is very likely a natural, monophyletic group. The characteristic location of the polar flagella within the outer membrane is almost certainly a synapomorphy. This system, which is a modification of Margulis and Schwartz (1988 and 1998) in which the phylum is designated B-4, reflects the general acceptance that it is monophyletic. We have raised the phylum of Margulis and Schwartz (1998) to the level of Kingdom with a single phylum. This group segregates well along the lines of cell structure. Bergey’s Manual of Systematic Bacteriology, volume 1, section 1 (Holt 1984) considers the group to be contained within a single Order (Spirochaetes) within the Division (phylum) Gracilicutes. Krieg (1984) acknowledges 2 major groups (families) within the order. Bergey’s Manual of Systematic Bacteriology, 2nd edition (Garrity et al. 2001 and 2003) treats the taxa that we include in the Spirochaetobacteria a natural group (phylum with a single class, a single order and three families). The spirochaetes appear to be associated with the proteobacteria (see Figure 6) and is based on Margulis and Schwartz (1998), with modifications from Garrity et al. (2001, 2003, and 2005), Tudge (2000), and Black (2002) in its overall topology. Note that the spirochetes also emerge within the same clade as the Proteobacteria in the All Species Living Tree Project (Yarza et al. 2008 and 2010; Munoz et al. 2011; see also Figure 7); however, the implication is that they must have emerged from within the Proteobacteria. |
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| FIGURE 1. A TEM cross section of a Treponema cell. OE=outer envelope, AF=axial filament, WM=membrane; BF=body fibrils (internal flagella) Image from http://biology.kenyon.edu/Microbial_Biorealm/bacteria/treponema/treponema.htm | FIGURE 2. A darkfield micrograph of Bourrelia burgdorferi, the causative agent of Lyme disease. Image from the CDC and in the Public Domain | FIGURE 3. SEM micrograph of Mixotricha paradoxa, a eukaryotic cell that enters into symbiosis with spirochetes to form cilia-like motile structures. Image by Dean Soulia, Wikimedia Commons | FIGURE 4. Micrograph of Spirochaeta americana from Mono Lake, California.. Image from NASA and in the Public Domain | FIGURE 5. Micrograph of Treponema pallidum, the causative agent of syphilis, from a silver preparation of a brain biopsy. Image from CDC and in the Public Domain |
FIGURE 6. In this cladogram the Spirochaetae (in shaded box) are sisters to the Proteobacteria. 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 7, a tree generated by the All Species Living Tree Project.
FIGURE 7. 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 spirochaetes is more complicated relative to the different proteobacterial groups.
| 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. Cleveland, L. R., and A. V. Grimstone, A.V. 1964. The fine structure of the flagellate Mixotricha paradoxa and its associated microorganisms. Proc. R. Soc. London, Ser. B. 159: 668–686. Ehrenberg, C. G. 1855. Uber den Grünsand und sein Eräuterung des organischen Lebens: Abhandlungen der königlichen Akademie der Wissenschaften, Berlin, Physikalische Abhandlungen, Berlin. pp. 85-176. 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. Hoover, R. B., E. V. Pikuta, A. K. Bej, D. Marsic, W. B. Whitman, J. Tang, and P. Krader. 2003. Spirochaeta americana sp. nov., a new haloalkaliphilic, obligately anaerobic spirochaete isolated from soda Mono Lake in California. International Journal of Systematic and Evolutionary Microbiology. 53: 815-821. Krieg, N. R. 1984. Gram-negative aerobic rods and cocci. In: Krieg, N. R. and J. G. Holt, eds. Bergey´s Manual of Systematic Bacteriology, Vol. 1: 140-408. Magot, M., M.-L. Fardeau, O. Arnauld, C. Lanau, B. Olivier, P. Thomas, and B. K. C. Patel. 1993. Spirochaeta smaragdinae sp. nov., a new mesophilic strictly anaerobic spirochete from an oil field. FEMS Microbiol. Lett. 155: 185-191. Margulis, L. 1993. Symbiosis in Cell Evolution. Freeman. New York. Margulis, L., M. F. Dolan, and R. Guerrero. 2000. The chimeric eukaryote: Origin of the nucleus from the karyomastigont in amitochondriate protists. Proc. Natl. Acad. Sci. USA. 97(13): 6954-6959. 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. 3nd 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. 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: 02/07/2013 |
