Chlorobaculum tepidum

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Chlorobaculum tepidum
Scientific classification
Domain:
Bacteria
Phylum:
Chlorobiota
Class:
"Chlorobia"
Order:
Chlorobiales
Family:
Chlorobiaceae
Genus:
Chlorobaculum
Species:
C. tepidum
Binomial name
Chlorobaculum tepidum
(Wahlund et al. 1996) Imhoff 2003
Synonyms

Chlorobium tepidumWahlund et al. 1996

Chlorobaculum tepidum, previously known as Chlorobium tepidum, [1] is an anaerobic, thermophilic green sulfur bacteria first isolated from New Zealand. [2] Its cells are gram-negative and non-motile rods of variable length. They contain chlorosomes [3] and bacteriochlorophyll a and c. [4]

Contents

Natural habitat and environmental requirements

Like other green sulfur bacteria C. tepidum requires light and specific compounds to perform anoxygenic photosynthesis. [3] C. tepidum differs from other green sulfur bacteria in that it cannot easily use H2 or Fe2+ as electron donors, relying on elemental sulfur, sulfide, and thiosulfate instead. [5] [6] [7] To fulfill their metabolic requirements, they reside primarily in anaerobic sulfur rich environments such as anaerobic levels of stratified lakes and lagoons, anaerobic levels of layered organic bacterial mats, and in hot springs where there is abundant sulfur. [7] C. tepidum and other green sulfur bacteria also play a large role within the carbon and sulfur cycles. [7] Within the sulfur cycle, they contribute to the oxidative branch by oxidizing reduced sulfur compounds. [8] Within anaerobic sediment layers C. tepidum is able to couple carbon and sulfur cycling in a metabolically favorable way. [8]

Photosynthetic mechanism

As it was mentioned before, C. tepidum performs anoxygenic photosynthesis. Within each cell there are 200–250 chlorosomes [3] that are attached to the cytoplasmic side of reaction centers inserted within the inner cell membrane. [3] The ellipsoidal shaped complexes act as light harvesting antenna to capture energy. [3] Within each chlorosome are 215,000 ± 80,000 bacteriochlorophyll C [4] that act as pigment molecules and absorb unique wavelengths of light relative to their color. [4] C. tepidum contains genes that play an important role in the methylation of the C-8 and C-12 carbons of bacteriochlorophyll C. This methylation allows for BChl C levels to fluctuate in response to a change in the availability of light, resulting in a high efficiency of light harvesting and allowing C. tepidum to survive in areas of very low light intensity. [9] [10] [11] Light energy is harvested by the chlorosomes and used in conjunction with H2, reduced sulfur compounds, or ferrous iron to preform redox reactions and provide energy to fix CO2 via the reverse tricarboxcylic acid cycle. [3]

Genome structure

C. tepidum contains a genome that contains 2.15 Mbp, within there are a total of 2,337 genes (of these genes, there are 2,245 protein coding genes and 56 tRNA and rRNA coding genes). [12] It's synthesis of chlorophyll a and bacteriochlorophylls a and c make it a model organism used to elucidate the biosynthesis of bacteriochlorophylls c. [13] Present in the genome of C. tepidum are a multitude of genes that protect the bacterium against the presence of oxygen. The fact that such a large part of the genome is used to encode for protections against oxygen points to the possibility that C. tepidum spent a long period of its evolutionary history in proximity to oxygen, and therefore needed pathways that ensured that living in the presence of oxygen would not substantially harm the bacterium. [14] [15] Several of its carotenoid metabolic pathways (including a novel lycopene cyclase) have similar counterparts in cyanobacteria. [16] [17]

See also

Related Research Articles

<span class="mw-page-title-main">Green sulfur bacteria</span> Family of bacteria

The green sulfur bacteria are a phylum, Chlorobiota, of obligately anaerobic photoautotrophic bacteria that metabolize sulfur.

<span class="mw-page-title-main">Bacteriochlorophyll</span> Chemical compound

Bacteriochlorophylls (BChl) are photosynthetic pigments that occur in various phototrophic bacteria. They were discovered by C. B. van Niel in 1932. They are related to chlorophylls, which are the primary pigments in plants, algae, and cyanobacteria. Organisms that contain bacteriochlorophyll conduct photosynthesis to sustain their energy requirements, but the process is anoxygenic and does not produce oxygen as a byproduct. They use wavelengths of light not absorbed by plants or cyanobacteria. Replacement of Mg2+ with protons gives bacteriophaeophytin (BPh), the phaeophytin form.

Chlorophyll <i>a</i> Chemical compound

Chlorophyll a is a specific form of chlorophyll used in oxygenic photosynthesis. It absorbs most energy from wavelengths of violet-blue and orange-red light, and it is a poor absorber of green and near-green portions of the spectrum. Chlorophyll does not reflect light but chlorophyll-containing tissues appear green because green light is diffusively reflected by structures like cell walls. This photosynthetic pigment is essential for photosynthesis in eukaryotes, cyanobacteria and prochlorophytes because of its role as primary electron donor in the electron transport chain. Chlorophyll a also transfers resonance energy in the antenna complex, ending in the reaction center where specific chlorophylls P680 and P700 are located.

<span class="mw-page-title-main">Purple bacteria</span> Group of phototrophic bacteria

Purple bacteria or purple photosynthetic bacteria are Gram-negative proteobacteria that are phototrophic, capable of producing their own food via photosynthesis. They are pigmented with bacteriochlorophyll a or b, together with various carotenoids, which give them colours ranging between purple, red, brown, and orange. They may be divided into two groups – purple sulfur bacteria and purple non-sulfur bacteria. Purple bacteria are anoxygenic phototrophs widely spread in nature, but especially in aquatic environments, where there are anoxic conditions that favor the synthesis of their pigments.

<span class="mw-page-title-main">Chromatiaceae</span> Family of purple sulfur bacteria

The Chromatiaceae are one of the two families of purple sulfur bacteria, together with the Ectothiorhodospiraceae. They belong to the order Chromatiales of the class Gammaproteobacteria, which is composed by unicellular Gram-negative organisms. Most of the species are photolithoautotrophs and conduct an anoxygenic photosynthesis, but there are also representatives capable of growing under dark and/or microaerobic conditions as either chemolithoautotrophs or chemoorganoheterotrophs.

Photoheterotrophs are heterotrophic phototrophs—that is, they are organisms that use light for energy, but cannot use carbon dioxide as their sole carbon source. Consequently, they use organic compounds from the environment to satisfy their carbon requirements; these compounds include carbohydrates, fatty acids, and alcohols. Examples of photoheterotrophic organisms include purple non-sulfur bacteria, green non-sulfur bacteria, and heliobacteria. These microorganisms are ubiquitous in aquatic habitats, occupy unique niche-spaces, and contribute to global biogeochemical cycling. Recent research has also indicated that the oriental hornet and some aphids may be able to use light to supplement their energy supply.

<span class="mw-page-title-main">Sulfur-reducing bacteria</span> Microorganisms able to reduce elemental sulfur to hydrogen sulfide

Sulfur-reducing bacteria are microorganisms able to reduce elemental sulfur (S0) to hydrogen sulfide (H2S). These microbes use inorganic sulfur compounds as electron acceptors to sustain several activities such as respiration, conserving energy and growth, in absence of oxygen. The final product of these processes, sulfide, has a considerable influence on the chemistry of the environment and, in addition, is used as electron donor for a large variety of microbial metabolisms. Several types of bacteria and many non-methanogenic archaea can reduce sulfur. Microbial sulfur reduction was already shown in early studies, which highlighted the first proof of S0 reduction in a vibrioid bacterium from mud, with sulfur as electron acceptor and H
2 as electron donor. The first pure cultured species of sulfur-reducing bacteria, Desulfuromonas acetoxidans, was discovered in 1976 and described by Pfennig Norbert and Biebel Hanno as an anaerobic sulfur-reducing and acetate-oxidizing bacterium, not able to reduce sulfate. Only few taxa are true sulfur-reducing bacteria, using sulfur reduction as the only or main catabolic reaction. Normally, they couple this reaction with the oxidation of acetate, succinate or other organic compounds. In general, sulfate-reducing bacteria are able to use both sulfate and elemental sulfur as electron acceptors. Thanks to its abundancy and thermodynamic stability, sulfate is the most studied electron acceptor for anaerobic respiration that involves sulfur compounds. Elemental sulfur, however, is very abundant and important, especially in deep-sea hydrothermal vents, hot springs and other extreme environments, making its isolation more difficult. Some bacteria – such as Proteus, Campylobacter, Pseudomonas and Salmonella – have the ability to reduce sulfur, but can also use oxygen and other terminal electron acceptors.

<i>Chlorobium</i> Genus of bacteria

Chlorobium is a genus of green sulfur bacteria. They are photolithotrophic oxidizers of sulfur and most notably utilise a noncyclic electron transport chain to reduce NAD+. Photosynthesis is achieved using a Type 1 Reaction Centre using bacteriochlorophyll (BChl) a. Two photosynthetic antenna complexes aid in light absorption: the Fenna-Matthews-Olson complex, and the chlorosomes which employ mostly BChl c, d, or e. Hydrogen sulfide is used as an electron source and carbon dioxide its carbon source.

<span class="mw-page-title-main">Chlorosome</span>

A chlorosome is a photosynthetic antenna complex found in green sulfur bacteria (GSB) and many green non-sulfur bacteria (GNsB), together known as green bacteria. They differ from other antenna complexes by their large size and lack of protein matrix supporting the photosynthetic pigments. Green sulfur bacteria are a group of organisms that generally live in extremely low-light environments, such as at depths of 100 metres in the Black Sea. The ability to capture light energy and rapidly deliver it to where it needs to go is essential to these bacteria, some of which see only a few photons of light per chlorophyll per day. To achieve this, the bacteria contain chlorosome structures, which contain up to 250,000 chlorophyll molecules. Chlorosomes are ellipsoidal bodies, in GSB their length varies from 100 to 200 nm, width of 50-100 nm and height of 15 – 30 nm, in GNsB the chlorosomes are somewhat smaller.

<i>Rhodospirillum rubrum</i> Species of bacterium

Rhodospirillum rubrum is a Gram-negative, pink-coloured bacterium, with a size of 800 to 1000 nanometers. It is a facultative anaerobe, thus capable of using oxygen for aerobic respiration under aerobic conditions, or an alternative terminal electron acceptor for anaerobic respiration under anaerobic conditions. Alternative terminal electron acceptors for R. rubrum include dimethyl sulfoxide or trimethylamine oxide.

<span class="mw-page-title-main">Fenna–Matthews–Olson complex</span>

The Fenna–Matthews–Olson (FMO) complex is a water-soluble complex and was the first pigment-protein complex (PPC) to be structure analyzed by x-ray spectroscopy. It appears in green sulfur bacteria and mediates the excitation energy transfer from light-harvesting chlorosomes to the membrane-embedded bacterial reaction center (bRC). Its structure is trimeric (C3-symmetry). Each of the three monomers contains eight bacteriochlorophyll a molecules. They are bound to the protein scaffold via chelation of their central magnesium atom either to amino acids of the protein or water-bridged oxygen atoms.

<span class="mw-page-title-main">Anoxygenic photosynthesis</span> Process used by obligate anaerobes

Anoxygenic photosynthesis is a special form of photosynthesis used by some bacteria and archaea, which differs from the better known oxygenic photosynthesis in plants in the reductant used and the byproduct generated.

<span class="mw-page-title-main">Bacterial phyla</span> Phyla or divisions of the domain Bacteria

Bacterial phyla constitute the major lineages of the domain Bacteria. While the exact definition of a bacterial phylum is debated, a popular definition is that a bacterial phylum is a monophyletic lineage of bacteria whose 16S rRNA genes share a pairwise sequence identity of ~75% or less with those of the members of other bacterial phyla.

<span class="mw-page-title-main">Isorenieratene</span> Chemical compound

Isorenieratene /ˌaɪsoʊrəˈnɪərətiːn/ is a carotenoid light harvesting pigment produced exclusively by the genus Chlorobium. Chlorobium are the brown-colored strains of the family of green sulfur bacteria (Chlorobiaceae). Green sulfur bacteria are anaerobic photoautotrophic organisms meaning they perform photosynthesis in the absence of oxygen using hydrogen sulfide in the following reaction:

Rhodovulum sulfidophilum is a gram-negative purple nonsulfur bacteria. The cells are rod-shaped, and range in size from 0.6 to 0.9 μm wide and 0.9 to 2.0 μm long, and have a polar flagella. These cells reproduce asexually by binary fission. This bacterium can grow anaerobically when light is present, or aerobically (chemoheterotrophic) under dark conditions. It contains the photosynthetic pigments bacteriochlorophyll a and of carotenoids.

Chlorobium chlorochromatii, originally known as Chlorobium aggregatum, is a symbiotic green sulfur bacteria that performs anoxygenic photosynthesis and functions as an obligate photoautotroph using reduced sulfur species as electron donors. Chlorobium chlorochromatii can be found in stratified freshwater lakes.

In some forms of photosynthetic bacteria, a chromatophore is a pigmented(coloured), membrane-associated vesicle used to perform photosynthesis. They contain different coloured pigments.

Rhodobacter capsulatus is a species of purple bacteria, a group of bacteria that can obtain energy through photosynthesis. Its name is derived from the Latin adjective "capsulatus", itself derived Latin noun "capsula", and the associated Latin suffix for masculine nouns, "-atus".

<span class="mw-page-title-main">Microbial oxidation of sulfur</span>

Microbial oxidation of sulfur is the oxidation of sulfur by microorganisms to build their structural components. The oxidation of inorganic compounds is the strategy primarily used by chemolithotrophic microorganisms to obtain energy to survive, grow and reproduce. Some inorganic forms of reduced sulfur, mainly sulfide (H2S/HS−) and elemental sulfur (S0), can be oxidized by chemolithotrophic sulfur-oxidizing prokaryotes, usually coupled to the reduction of oxygen (O2) or nitrate (NO3−). Anaerobic sulfur oxidizers include photolithoautotrophs that obtain their energy from sunlight, hydrogen from sulfide, and carbon from carbon dioxide (CO2).

Thiodictyon is a genus of gram-negative bacterium classified within purple sulfur bacteria (PSB).

References

  1. ↑ Imhoff J (2003). "Phylogenetic taxonomy of the family Chlorobiaceae on the basis of 16S rRNA and fmo (Fenna– Matthews–Olson protein) gene sequences" (PDF). International Journal of Systematic and Evolutionary Microbiology. 53 (Pt 4): 941–951. doi:10.1099/ijs.0.02403-0. PMID   12892110.
  2. ↑ Wahlund TM, Woese CR, Castenholz RW, Madigan MT (1991). "A thermophilic green sulfur bacterium from New Zealand hot springs, Chlorobium tepidum sp. nov". Archives of Microbiology. 156 (2): 81–90. Bibcode:1991ArMic.156...81W. doi:10.1007/BF00290978. ISSN   0302-8933. S2CID   22133132.
  3. 1 2 3 4 5 6 Frigaard NU, Chew AG, Li H, Maresca JA, Bryant DA (2003). "Chlorobium Tepidum : Insights into the Structure, Physiology, and Metabolism of a Green Sulfur Bacterium Derived from the Complete Genome Sequence". Photosynthesis Research. 78 (2): 93–117. Bibcode:2003PhoRe..78...93F. doi:10.1023/B:PRES.0000004310.96189.b4. ISSN   0166-8595. PMID   16245042. S2CID   30218833.
  4. 1 2 3 Montano GA, Bowen BP, LaBelle JT, Woodbury NW, al e (October 2003). "Characterization of Chlorobium tepidum chlorosomes: A calculation of bacteriochlorophyll c per chlorosome and oligomer modeling". Biophysical Journal. 85 (4): 2560–2565. Bibcode:2003BpJ....85.2560M. doi:10.1016/S0006-3495(03)74678-5. PMC   1303479 . PMID   14507718. ProQuest   215720771.
  5. ↑ Levy AT, Lee KH, Hanson TE (2016). Parales RE (ed.). "Chlorobaculum tepidum Modulates Amino Acid Composition in Response to Energy Availability, as Revealed by a Systematic Exploration of the Energy Landscape of Phototrophic Sulfur Oxidation". Applied and Environmental Microbiology. 82 (21): 6431–6439. Bibcode:2016ApEnM..82.6431L. doi:10.1128/AEM.02111-16. ISSN   0099-2240. PMC   5066360 . PMID   27565613.
  6. ↑ Kushkevych I, Procházka J, Gajdács M, Rittmann SK, Vítězová M (2021-06-15). "Molecular Physiology of Anaerobic Phototrophic Purple and Green Sulfur Bacteria". International Journal of Molecular Sciences. 22 (12): 6398. doi: 10.3390/ijms22126398 . ISSN   1422-0067. PMC   8232776 . PMID   34203823.
  7. 1 2 3 Li H, Jubelirer S, Garcia Costas AM, Frigaard NU, Bryant DA (2009). "Multiple antioxidant proteins protect Chlorobaculum tepidum against oxygen and reactive oxygen species". Archives of Microbiology. 191 (11): 853–867. Bibcode:2009ArMic.191..853L. doi:10.1007/s00203-009-0514-7. ISSN   0302-8933. PMID   19784828. S2CID   8881227.
  8. 1 2 Rodriguez J, Hiras J, Hanson TE (2011). "Sulfite Oxidation in Chlorobaculum Tepidum". Frontiers in Microbiology. 2: 112. doi: 10.3389/fmicb.2011.00112 . ISSN   1664-302X. PMC   3119408 . PMID   21747809.
  9. ↑ Chew AG, Frigaard NU, Bryant DA (2007). "Bacteriochlorophyllide c C-8 2 and C-12 1 Methyltransferases Are Essential for Adaptation to Low Light in Chlorobaculum tepidum". Journal of Bacteriology. 189 (17): 6176–6184. doi:10.1128/JB.00519-07. ISSN   0021-9193. PMC   1951906 . PMID   17586634.
  10. ↑ Morgan-Kiss RM, Chan LK, Modla S, Weber TS, Warner M, Czymmek KJ, Hanson TE (2009-01-01). "Chlorobaculum tepidum regulates chlorosome structure and function in response to temperature and electron donor availability". Photosynthesis Research. 99 (1): 11–21. Bibcode:2009PhoRe..99...11M. doi:10.1007/s11120-008-9361-7. ISSN   1573-5079. PMID   18798007.
  11. ↑ Shoji S, Mizoguchi T, Tamiaki H (2016). "In vitro self-assemblies of bacteriochlorophylls-c from Chlorobaculum tepidum and their supramolecular nanostructures". Journal of Photochemistry and Photobiology A: Chemistry. 331: 190–196. doi:10.1016/j.jphotochem.2015.11.003. ISSN   1010-6030.
  12. ↑ Eisen JA, Nelson KE, Paulsen IT, et al. (July 2002). "The complete genome sequence of Chlorobium tepidum TLS, a photosynthetic, anaerobic, green-sulfur bacterium". Proceedings of the National Academy of Sciences of the United States of America . 99 (14): 9509–14. Bibcode:2002PNAS...99.9509E. doi: 10.1073/pnas.132181499 . PMC   123171 . PMID   12093901.
  13. ↑ N.-U. Frigaard, et al. (2006). B. Grimm, et al. (eds.). Chlorophylls and Bacteriochlorophylls: Biochemistry, Biophysics, Functions and Applications. Vol. 25. Springer. 201–221.
  14. ↑ Harada J, Mizoguchi T, Tsukatani Y, Yokono M, Tanaka A, Tamiaki H (2014). "Chlorophyllide a Oxidoreductase Works as One of the Divinyl Reductases Specifically Involved in Bacteriochlorophyll a Biosynthesis". Journal of Biological Chemistry. 289 (18): 12716–12726. doi: 10.1074/jbc.m113.546739 . ISSN   0021-9258. PMC   4007461 . PMID   24637023.
  15. ↑ Li H, Jubelirer S, Garcia Costas AM, Frigaard NU, Bryant DA (2009-11-01). "Multiple antioxidant proteins protect Chlorobaculum tepidum against oxygen and reactive oxygen species". Archives of Microbiology. 191 (11): 853–867. Bibcode:2009ArMic.191..853L. doi:10.1007/s00203-009-0514-7. ISSN   1432-072X. PMID   19784828.
  16. ↑ N.-U. Frigaard, et al. (2004). "Genetic manipulation of carotenoid biosynthesis in the green sulfur bacterium Chlorobium tepidum". Journal of Bacteriology. 186 (16): 5210–5220. doi:10.1128/jb.186.16.5210-5220.2004. PMC   490927 . PMID   15292122.
  17. ↑ J.A. Maresca, et al. (2005). A. van der Est, D. Bruce (eds.). Photosynthesis: Fundamental Aspects to Global Perspectives. Allen Press. pp. 884–886.

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