Roseiflexus castenholzii

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Classification

Domain: Bacteria

Phylum: Chloroflexi

Class: Chloroflexi

Order: Chloroflexales

Family: Chloroflexaceae

Species

NCBI: Taxonomy

Roseiflexus castenholzii

Description and Significance

Roseiflexus castenholzii is gram negative and is classified as a green, nonsulfur bacteria. Colonies that were found were red to reddish brown in color. Roseiflexus castenholzii is an unbranched multicellular filamentous organism that does not have a defined length but the diameter is .8 to 1.0 μm. R. castenholzii has no flagella and show signs of gliding motility. An unusual aspect of this organism is that it lacks chlorosomes, which can usually be found in related species, and intracytoplasmic membranes.

Roseiflexus castenholzii is thermophilic and found on microbial mats in hot springs, and was originally found in the Nakabusa hot springs in Japan. Ideal conditions to live at are a water temperature ranging from 45 to 55 degrees Celsius and a pH from 7 to 9. The organism can function under aerobic and anaerobic conditions.

Genome Structure

Roseiflexus castenholzii has a single, circular chromosome with a length of 5,723,298 base pairs. There are also 4,330 protein genes and 56 RNA genes. The G+C content of this organism is to some extent higher than other related species.

Cell Structure, Metabolism and Life Cycle

Roseiflexus castenholzii is a phototrophic microorganism that forms unbranched, multicellular filaments of indefinite length. These unbranched filaments are made up of smaller segments that cause them to resemble a string of beads and may be intertwined with one another.

These bacteria are unique in that they lack chlorosomes, which are light-harvesting intracellular vesicles that are usually present in green sulfur and green nonsulfur bacteria. This causes it to be the first culturable filamentous anoxygenic phototroph (FAP) that lacks chlorosomes (Yamada, M., et al.). They do, however, contain bacteriochlorophyll (Bchl) a as well as γ carotene derivatives, which contribute to their ability to photosynthesize. R. castenholzii is classified as a FAP but can reproduce under either aerobic or anaerobic conditions and in either a light or dark environment. In experiments conducted on Roseiflexus strains from Yellowstone National Park it was found that bicarbonate was present among the FAPs. In conjunction with Roseiflexus’s 3-hydroxypropionate pathway, there exists a possible ability to grow by means of photoautotrophy (Van der Meer, M. T., et al.). Attempts to confirm this finding have been unsuccessful since R. castenholzii has shown no growth with bicarbonate as a sole carbon source in lab settings (Hanada, S., et al.).

Under anaerobic light conditions, R. castenholzii harvests energy via photoheterotrophy. This implies that it uses light as an energy source when it is readily available and organic materials as a source of carbon. It was demonstrated that only under light conditions were organic materials such as citrate, lactate, glucose, and casamino acids used as the sole carbon source (Hanada, S., et al.).

On the contrary, R. castenholzii becomes chemoheterotrophic when faced with an aerobic dark environment. When light is not available, the energy is instead gathered from oxidizing inorganic materials while organic materials provide the carbon source. The oxidation process requires the presence of oxygen, rendering the bacterium unable to grow under anaerobic dark conditions.

Ecology and Pathogenesis

Habitat; symbiosis; biogeochemical significance; contributions to environment.
If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

References

Collins, A. M. "Light-harvesting and the primary photochemistry of Roseiflexus castenholzii". Ann Arbor: ProQuest, 2010.

Hanada, S., Takaichi, S., Matsuura, K., and Nakamura, K. "Roseiflexus castenholzii gen. nov., sp. nov., a thermophilic, filamentous, photosynthetic bacterium that lacks chlorosomes". International Journal of Systematic and Evolutionary Microbiology. 2002. Volume 52. p. 187-193.

Herter, S., Farfsing, J., Gad'On, N., Rieder, C., Eisenreich, W., Bacher, A., and Fuchs, G. "Autotrophic CO(2) fixation by Chloroflexus aurantiacus: study of glyoxylate formation and assimilation via the 3-hydroxypropionate cycle". Journal of Bacteriology. 2001. Volume 183. Issue 14. p. 4305-4316.

Klatt, C. G., Bryant, D. A., and Ward, D. M. "Comparative genomics provides evidence for the 3-hydroxypropionate autotrophic pathway in filamentous anoxygenic phototrophic bacteria and in hot spring microbial mats". Environmental Microbiology. 2007. Volume 9. Issue 8. p. 2067-2078.

Van der Meer, M. T., Klatt, C. G., Wood, J., Bryant, D. A., Bateson, M. M., Lammerts, L., Schouten, S., Damste, J. S., Madigan, M. T., and Ward, D. M. "Cultivation and genomic, nutritional, and lipid biomarker characterization of Roseiflexus strains closely related to predominant in situ populations inhabity Yellowstone hot spring microbial mats". Journal of Bacteriology. 2010. Volume 192. Issue 12. p. 3033-3042.

Van der Meer, M. T., Schouten, S., Bateson, M. M., Nubel, U., Wieland, A., Kuhl, M., de Leeuw, J. W., Sinninghe Damste, J. S., and Ward, D. M. "Diel variations in carbon metabolism by green nonsulfur-like bacteria in alkaline siliceous hot spring microbial mats from Yellowstone National Park". Applied and Environmental Microbiology. 2005. Volume 71. Issue 7. p. 3978-3986.

Yamada, M., Zhang, H., Hanada, S., Nagashima, K. V., Shimada, K., and Matsuura, K. "Structural and spectroscopic properties of a reaction center complex from the chlorosome-lacking filamentous anoxygenic phototrophic bacterium Roseiflexus castenholzii". Journal of Bacteriology. 2005. Volume 187. Issue 5. p. 1702-1709.

Author

Page authored by Jessica Lefere and Bernice Li, students of Prof. Jay Lennon at Michigan State University.

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