Roseiflexus castenholzii

Last updated

Roseiflexus castenholzii
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Bacteria
Kingdom: Bacillati
Phylum: Chloroflexota
Class: Chloroflexia
Order: Chloroflexales
Family: Roseiflexaceae
Genus: Roseiflexus
Species:
R. castenholzii
Binomial name
Roseiflexus castenholzii
Hanada et al., 2002

Roseiflexus castenholzii is a heterotrophic, thermophilic, filamentous anoxygenetic phototroph (FAP) bacterium. [1] This species is in one of two genera of FAPs that lack chlorosomes. [2] [3] R. castenholzii was first isolated from red-colored bacterial mats located Nakabusa hot springs in Japan. [1] Because this organism is a phototroph, it utilizes photosynthesis to fix carbon dioxide and build biomolecules. R. castenholzii has three photosynthetic complexes: light-harvesting only, reaction center only, and light-harvesting with reaction center. [4]

Contents

Morphology

This bacterium has a cell diameter is of 0.8–1.0 micrometers but does not have a definite length because of its multicelluar filamentous structure. The bacterium is red to reddish-brown forms distinct red bacterial mats in the natural environment. [2] R. castenholzii lacks internal vesicles, internal membranes, and complex structures. This species has gliding motility. [1]

Phylogeny

The five currently known genera of FAP organisms are Chlorofelxus, Choronema, Oscillochloris, Roseiflexus, and Heliothrix. Of these five, only two do not contain chlorosomes: Roseiflexus and Heliothrix. [3] Roseiflexus and Heliothrix are both red due to only having Bchl a as a photosyntheic pigment. In most other aspects, both phenotypically and genetically, the genera Roseiflexus and Heliothrix are different from each other. [3] Little is known about the taxonomy of the Roseiflexus genus due to it only containing one known species: Roseiflexus casternholzii.

Habitat

When first discovered, Roseiflexuscastenholzii was isolated from the lowest layer of a three layered bacterial mat; the top two layers contained cyanobacteria and Chloroflexus spp. [3] These mats were found in multiple Japanese hot springs ranging in temperature from 45.5 °C to 68.5 °C and with a neutral to alkaline pH range. [1] [3]

This bacterium is able to grow photoheterotrophically under anaerobic light conditions and chemoheterotrophically under aerobic dark conditions. Optimal growth conditions for this organism are 50 °C and pH 7.5–8.0. The first isolated type strain was HLO8T (= DSM 13941T = JCM 11240T). [1] [2]

Photosynthesis

In order to conduct photosynthesis, Roseiflexuscastenholzii contains three different complexes: light-harvesting only (LH), reaction center only (RC) and light-harvesting with reaction center (LHRC). [4] In contrast to most other FAPs, R.castenholzii does not have chlorosomes, which contain great amounts of photosynthetic pigments. [4] Because chlorosomes can obstruct observations of photosynthetic complexes, Roseiflexuscastenholzii is considered a model organism to study the reaction centers FAPs have. [4]

The LHRC contains both light harvesting and reaction center peptides that allow for absorbing light and exciting electrons in one complex. [5] The light-harvesting complex contains antenna pigments that allow the bacterium to absorb light around 800 nanometers. [5] The majority of these pigments are bacteriochlorophyll (BChl). [4] The reaction center in Roseiflexuscastenholzii is closely related to the RC of Chloroflexusaurantiacus. R.castenholzii's RC complex contains three subunits: L, M, and a c-type cytochrome. It lacks the H subunit common in purple bacteria. [5] The RC also contains BChl and bacteriopheophytin (BPhe) pigments. [6] [4]

References

  1. 1 2 3 4 5 Hanada S, Takaichi S, Matsuura K, Nakamura K (January 2002). "Roseiflexus castenholzii gen. nov., sp. nov., a thermophilic, filamentous, photosynthetic bacterium that lacks chlorosomes". International Journal of Systematic and Evolutionary Microbiology. 52 (Pt 1): 187–193. doi: 10.1099/00207713-52-1-187 . PMID   11837302.
  2. 1 2 3 Dworkin M, Falkow S (2006). The prokaryotes. Vol. 7. Proteobacteria : delta and epsilon subclasses, deeply rooting bacteria : a handbook on the biology of bacteria (3rd ed.). New York: Springer. ISBN   978-0-387-30747-3. OCLC   262687432.
  3. 1 2 3 4 5 Hanada S, Pierson BK (2006). "The Family Chloroflexaceae". In Dworkin M, Falkow S, Rosenberg E, Schleifer KH (eds.). The Prokaryotes. New York, NY: Springer New York. pp. 815–842. doi:10.1007/0-387-30747-8_33. ISBN   978-0-387-25497-5.
  4. 1 2 3 4 5 6 Collins AM, Qian P, Tang Q, Bocian DF, Hunter CN, Blankenship RE (September 2010). "Light-harvesting antenna system from the phototrophic bacterium Roseiflexus castenholzii". Biochemistry. 49 (35): 7524–7531. doi:10.1021/bi101036t. PMID   20672862.
  5. 1 2 3 Collins AM, Xin Y, Blankenship RE (August 2009). "Pigment organization in the photosynthetic apparatus of Roseiflexus castenholzii". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1787 (8): 1050–1056. doi:10.1016/j.bbabio.2009.02.027. PMID   19272352.
  6. ↑ Yamada M, Zhang H, Hanada S, Nagashima KV, Shimada K, Matsuura K (March 2005). "Structural and spectroscopic properties of a reaction center complex from the chlorosome-lacking filamentous anoxygenic phototrophic bacterium Roseiflexus castenholzii". Journal of Bacteriology. 187 (5): 1702–1709. doi:10.1128/JB.187.5.1702-1709.2005. PMC   1063993 . PMID   15716441.

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.