DESCRIPTION OF THE KINGDOM CHLOROSULFATAE AND ITS SINGLE PHYLUM CHLOROBACTERIA
| EUBACTERIA> PROTEOBACTERIAE> CHLOROSULFATAE> CHLOROBACTERIA |
KINGDOM CHLOROSULFATAE LINKS
| Chlorosulfatae (klo-ro-sul-FAT-e) is derived from the name, Green Sulfur Bacteria with a Greek (chloro – χλοερός) and Latin root (sulfur meaning brimstone). This is a standardization of the name for the group called Chlorobi (Garrity and Holt 2001), after Chlorobium, a common genus in the kingdom. |
| INTRODUCTION TO THE KINGDOM CHLOROSULFATAE AND ITS SINGLE PHYLUM, CHLOROBACTERIA1 These photosynthetic green sulfur bacteria are anaerobes and are often found at the interface between anoxic layers of water and an upper oxygen bearing layer that allows sufficient light penetration to drive photosynthesis. Typically, they occur in anoxic regions of clear lakes, sulfur springs, and anoxic sediments in salt marshes. The organisms are nonmotile and range from straight or curved rods (Figure 1) to spheres with prosthecae (text with tooltip) Prosthece are buds that arise from the cell surface. In bacteria like Caulobacter the buds develop into stalks and other structures. to branching filaments. Members of this kingdom have specialized photosynthetic membranes called chlorosomes (text with tooltip) Chlorosomes are thyllakoid-like structures. (see Figure 2) or thylakoids on which they have bacteriochlorophylls (text with tooltip) Bacteriochlorophylls are prokaryotic photosynthetic pigments that are related to chlorophylls of eukaryotes. c and d or e. Their photosynthetic pigments make them green or brown in appearance. All utilize a modification of the Krebs Cycle for the fixation of carbon dioxide. In short, the green sulfur bacteria use light energy to generate ATP, and they use H2, H2S, or reduced sulfur compounds to reduce CO2 to a form of organic carbon. They generally have the ability to take reduced sulfur species (sulfide, thiosulfide or sulfite) and oxidize them to sulfate or elemental sulfur. The Green Sulfur Bacteria clearly are different from the other anoxygenic phototrophs and should be separated despite their superficial similarities. To that end we follow the system of Margulis and Schwartz (1998) who separate Chlorobia (B-8) and raise it to phylum status. Bergey’s Manual of Systematic Bacteriology, volume 3, section 18 (Holt 1989a) lumps all of the Anoxygenic Phototrophic Bacteria into 2 subgroups: Purple Bacteria and Green Bacteria. Volume 4 of Bergey’s Manual (Holt 1989b) classify this group in the Class Anoxyphotobacteria within the Division (phylum) Gracilicutes. Bergey’s Manual of Systematic Bacteriology, 2nd edition (Garrity et al. 2001) treats the taxa that we include in the Chlorosulfatae as Phylum B XI (Chlorobi). The Chlorosulfatae has been in the crown group of the Eubacteria (Garrity et al. 2001, 2003, and 2005; see Figure 3) consistently and the All Species Living Tree Project (Yarza et al. 2008 and 2010; Munoz et al. 2011; see Figure 4) also places them there. Note, however, that The All Species Living Tree Project associates Chlorosulfatae (Chlorobi) together in a clade (Bacteriodetes + Chlorobi + Fibrobacteres + Gemmatimodates). |
 |  |
| FIGURE 1. Chlorobium viewed with a light microscope. Image from http://biology.kenyon.edu/Microbial_Biorealm/bacteria/bacteroidete_chlorob_group/Chlorobium/chlorobium.htm | FIGURE 2. A TEM micrograph of Chlorobium showing the
chlorosomes
(text with tooltip)
Chlorosomes are thyllakoid-like structures.
just beneath the cell membrane. Image from http://biology.kenyon.edu/Microbial_Biorealm/bacteria/bacteroidete_chlorob_group/Chlorobium/chlorobium.htm |
FIGURE 3. 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 4, a tree generated by the All Species Living Tree Project. It is similar, though with its association of Chlorosulfatae (in shaded box) with Saprospirae, taxa included in the Bacteriodetes + Chlorobi + Fibrobacteres + Gemmatimodates clade.
FIGURE 4. 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 Bacteriodetes + Chlorobi + Fibrobacteres + Gemmatimodates) suggests a very different systematic treatment.
| 1. Chlorosulfatae is a name that is derived from Chlorobi, but indicates that these are the green sulfur bacteria. Chlorobacteria is a standardization of Chlorobi as a phylum name. |
| 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. Holt, J. G., ed. 1989a. Other gram-negative bacteria, Cyanobacteria, Archaea. IN: Bergey’s manual of systematic bacteriology. Volume III. Williams and Wilkins. Baltimore, MD. Holt, J. G. ed. 1989b. Other gram-positive bacteria. IN: Bergey’s manual of systematic bacteriology. Volume IV. Williams and Wilkins. Baltimore, MD. [L] 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. |
| By Jack R. Holt. Last revised: 02/11/2013 |
