T. rosea is a purple sulfur bacteria. All purple sulfur bacteria are members of the gamma group of the Proteobacteria. They are gram negative, anoxygenic phototrophs that utilize hydrogen sulfide as a primary electron donor. They are found in anaerobic conditions like freshwater or marine environments. Purple sulfur bacteria can express purple, red, brown, and orange pigments and their structure may include intracellular sulfur granule deposits and gas vacuoles.
T. rosea has several unique characteristics. It is pink in color, and has extensive gas vacuoles that allow it to change its buoyancy. They grow underwater in vertical sheets formed from 8 to 64 cells. Since the purple sulfur bacteria are generally a larger bacteria, sheets of T. rosea can grow to be 2 – 3 centimeters long. T. rosea is an alkaliphile (can grow at pH above 9) that thrives mainly in waste lagoons, and because it uses hydrogen sulfide as an electron donor, it plays a practical role in the environment as an odor reducer.
In one particular case, two scientists, Thomas Wenke and Judith Vogt, studied patterns of T. rosea in a livestock waste lagoon. They noticed a predominant pink color in the lagoon during the fall months, but not as much during the winter, spring, and summer. They observed the sulfide concentrations in the lagoon and found that the concentrations were much higher in the winter months. T. rosea can only survive up to a maximum sulfide concentration of 3.2 mg/liter. In the winter months, the concentration rose well above this, and in turn killed off most of the T. rosea that was present. It took until the fall for the species to re-grow and again become predominant in the lagoon.Since T. rosea is an anoxygenic phototroph, it does require hydrogen sulfide as an electron donor. However, Wenke and Vogt’s study proved that too much of something CAN be a bad thing.
References:
Burnette, Ryan N. “Purple Sulfur Bacteria.” http://soils1.cses.vt.edu/ch/biol_4684/Microbes/purprnb.html
Thar, Ronald, and Kuhl, Michael. “Motility of Marichromatium gracile in Response to Light, Oxygen, and Sulfide.” Applied and Environmental Biology 67 (2001): 5410-5419 http://aem.asm.org/cgi/content/full/67/12/5410
Todar, Kenneth. “Major Groups of Prokaryotes.” 2002. http://www.bact.wisc.edu/Bact303/MajorGroupsOfProkaryotes
Wenke, Thomas L. and Vogt, Judith C. “Temporal Changes in a Pink Feedlot Lagoon.” Applied and Environmental Biology 41 (1981): 381-385 http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=243703&action=stream&blobtype=pdf
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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