Trichodesmium thiebautii

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Trichodesmium thiebautii
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Bacteria
Phylum: Cyanobacteria
Class: Cyanophyceae
Order: Oscillatoriales
Family: Microcoleaceae
Genus: Trichodesmium
Species:
T. thiebautii
Binomial name
Trichodesmium thiebautii

Trichodesmium thiebautii is a cyanobacteria that is often found in open oceans of tropical and subtropical regions and is known to be a contributor to large oceanic surface blooms. [1] This microbial species is a diazotroph, meaning it fixes nitrogen gas (N2), but it does so without the use of heterocysts. [2] T. thiebautii is able to simultaneously perform oxygenic photosynthesis. [2] T. thiebautii was discovered in 1892 by M.A. Gomont. [3] T. thiebautii are important for nutrient cycling in marine habitats because of their ability to fix N2, a limiting nutrient in ocean ecosystems. [1]

Contents

Discovery

In 1830 the cyanobacteria genus Trichodesmium was first found in samples collected in marine waters surrounding Egypt and Syria, and described based on morphological features. [4] In 1892, approximately sixty years following the initial discovery of the genus, Gomont described two new species, T. thiebautii and T. hildebrandtii, based on specific morphological characteristics, particularly trichome shape. [5] T. thiebautii was first cultured in a lab in 1993, from water samples collected in North Carolina coastal waters, using a sterilized oligotrophic seawater solution with an addition of 25 mg liter−1 Tricine buffer and adjusted to a pH of 8.17. [3]

Taxonomy

The highly diverse colonial and cellular morphologies among Trichodesmium species have caused much debate about the phylogeny of the genus. [2] Upon initial discovery by Ehrenberg in 1830, the genus Trichodesmium was placed in the family Oscillatoriaceae. More recently, an examination of several key morphological characteristics including colony formation associated with sheath production, cell differentiation along the trichome, and fatty acid composition led to the placement of Trichodesmium thiebautii into the family Phormidiaceae and order Oscillatoriales. [6] Many species originally placed into the family Phormidiaceae, including Trichodesmium spp., were taxonomically relocated in 2005 by two researchers, J. Komárek and K. Anagnostidis, into the family Microcoleaceae, where they remain today. [7]

Analysis of the 16s rRNA from Trichodesmium sp. strain NlBB 1067 indicated that its closest phylogenetic neighbor is Oscillatoria PCC 7515 [ dead link ] with 94.9% sequence similarity. [8] This close sequence similarity did not resolve the debate on separation of Trichodesmium into a separate genus from Oscillatoria. However, a genetic analysis of the nitrogenase nifH gene sequences of Trichodesmium spp, including T. thiebautii, revealed a distinct cluster within the cyanobacteria clade with very deep branches indicating an early evolutionary radiation. [2] Capone et al. (1997) suggested that the large genetic distance of the nifH gene between Trichodesmium spp. and other species of cyanobacteria, including those in the genus Oscillatoria, may be due to the structural requirements of aerobic N2 fixation. [2]

Characterization

Physical characteristics

Members of the family Microcoleaceae have a distinct radial arrangement of their thylakoids that distinguishes them from other closely related families of cyanobacteria. [9] Trichodesmium thiebautii is usually composed of a few to hundreds of cells in a colony and has trichomes that appear to be twisted together much like a rope with radiating ends. [5] Researchers examining Trichodesmium spp. in surface waters across the world also observed the rope-like twisted trichomes mentioned by Gomont, under the scanning electron microscope (SEM). [10] In the original description of T. thiebautii, each cell was said to be twice as long as it was wide. [5] More than 100 years later, researchers were able to cultivate T. thiebautii and saw various colony morphologies ranging from solitary cells to spherical and fusiform (spindle-shaped) aggregates. [3] T. thiebautii's most distinct physical cellular structures are a series of gas vesicles found within the cell that allow it to be naturally buoyant and remain at the ocean's surface. [2] In lab cultures, T. thiebautii exhibits growth of 0.23 division per day, and individual cells are 4–6 μm with trichomes ranging in width from 8 to 10 μm. [3]

Metabolism

Trichodesmium thiebautii is a simultaneous diazotroph and autotroph. [11] [2] [12] These bacteria perform daily cycling of their nitrogenase enzyme. New molecules of nitrogenase are synthesized every morning, inactivated in the afternoon, and degraded at night, with a peak in enzyme activity at midday. [13] [11] T. thiebautii is also capable of taking up combined nitrogen (i.e., nitrate, nitrite, ammonia, urea) and will experience a reduction in nitrogenase activities when these other nitrogen sources are available to it. [11]

Ecology

Trichodesmium species are ubiquitous to oligotrophic tropical and subtropical aquatic environments that are known for deep light penetration, clear waters and a stable water column. [1] [2] A key feature to the genus is the presence of gas vesicles, which allow it to stay closer to the surface for photosynthesis. [2] They’re important ecologically due to their significant contribution of new nitrogen input for the planet’s oceans. [1] This species is capable of forming large surface blooms that occur when wind stresses are low and Trichodesmium thiebautii is able to accumulate, undisturbed, on the surface of the water. [2]

Genomics

Trichodesmium thiebautii has a genome size of approximately 3.29 Mb with 3370 genes of which 3335 are protein-coding. It has a G-C content of 35.35%. [14] [15]

Importance

Trichodesmium species are known for creating surface blooms in aquatic environments under the right conditions. [1] T. thiebautii and T. erythraeum are often the main cyanobacteria associated with production of the large blooms, though other Trichodesium species can also be found contributing to process. [1] The blooms may cause an increase in inorganic and organic nutrients that can effect light penetration, which influences phytoplankton successions and productivity. [2] Trichodesmium is a genus of non-heterocystous cyanobacteria with a unique metabolism that allows them to that fix N2 while also undergoing oxygenic photosynthesis. It has been estimated that Trichodesmium spp. are responsible for a significant portion, perhaps as much as 25%, of the nitrogen cycling in oceanic ecosystems. [16] [17] The role of T. thiebautii, and other members of its genus, in oceanic nitrogen cycling is significant because nitrogen is an essential element for life. [16] Nitrogen is present in microbial cell structures and used for nucleic acid as well as protein synthesis. [16] In aquatic habitats, nitrogen is often a limiting nutrient in regards to productivity and fixing it from the atmosphere is necessary to allow organisms to utilize it for the biosynthesis of molecules necessary for life. [11]

Related Research Articles

Nitrogen fixation is a chemical process by which molecular nitrogen (N
2), which has a strong triple covalent bond, is converted into ammonia (NH
3) or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. The nitrogen in air is molecular dinitrogen, a relatively nonreactive molecule that is metabolically useless to all but a few microorganisms. Biological nitrogen fixation or diazotrophy is an important microbe-mediated process that converts dinitrogen (N2) gas to ammonia (NH3) using the nitrogenase protein complex (Nif).

<span class="mw-page-title-main">Cyanobacteria</span> Phylum of photosynthesising prokaryotes

Cyanobacteria, also called Cyanobacteriota or Cyanophyta, are a phylum of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" refers to their cyan color, which forms the basis of cyanobacteria's informal common name, blue-green algae, although as prokaryotes they are not scientifically classified as algae. They appear to have originated in a freshwater or terrestrial environment.

<i>Trichodesmium</i> Genus of bacteria

Trichodesmium, also called sea sawdust, is a genus of filamentous cyanobacteria. They are found in nutrient poor tropical and subtropical ocean waters. Trichodesmium is a diazotroph; that is, it fixes atmospheric nitrogen into ammonium, a nutrient used by other organisms. Trichodesmium is thought to fix nitrogen on such a scale that it accounts for almost half of the nitrogen fixation in marine systems globally. Trichodesmium is the only known diazotroph able to fix nitrogen in daylight under aerobic conditions without the use of heterocysts.

Diazotrophs are bacteria and archaea that fix atmospheric nitrogen(N2) in the atmosphere into bioavailable forms such as ammonia.

<i>Oscillatoria</i> Genus of bacteria

Oscillatoria is a genus of sugar making microscopic creatures.

<i>Aphanizomenon flos-aquae</i> Species of bacterium

Aphanizomenon flos-aquae is a brackish and freshwater species of cyanobacteria of the genus Aphanizomenon found around the world, including the Baltic Sea and the Great Lakes.

<span class="mw-page-title-main">Cyanophage</span> Virus that infects cyanobacteria

Cyanophages are viruses that infect cyanobacteria, also known as Cyanophyta or blue-green algae. Cyanobacteria are a phylum of bacteria that obtain their energy through the process of photosynthesis. Although cyanobacteria metabolize photoautotrophically like eukaryotic plants, they have prokaryotic cell structure. Cyanophages can be found in both freshwater and marine environments. Marine and freshwater cyanophages have icosahedral heads, which contain double-stranded DNA, attached to a tail by connector proteins. The size of the head and tail vary among species of cyanophages. Cyanophages infect a wide range of cyanobacteria and are key regulators of the cyanobacterial populations in aquatic environments, and may aid in the prevention of cyanobacterial blooms in freshwater and marine ecosystems. These blooms can pose a danger to humans and other animals, particularly in eutrophic freshwater lakes. Infection by these viruses is highly prevalent in cells belonging to Synechococcus spp. in marine environments, where up to 5% of cells belonging to marine cyanobacterial cells have been reported to contain mature phage particles.

<i>Aphanizomenon</i> Genus of bacteria

Aphanizomenon is a genus of cyanobacteria that inhabits freshwater lakes and can cause dense blooms. They are unicellular organisms that consolidate into linear (non-branching) chains called trichomes. Parallel trichomes can then further unite into aggregates called rafts. Cyanobacteria such as Aphanizomenon are known for using photosynthesis to create energy and therefore use sunlight as their energy source. Aphanizomenon bacteria also play a big role in the Nitrogen cycle since they can perform nitrogen fixation. Studies on the species Aphanizomenon flos-aquae have shown that it can regulate buoyancy through light-induced changes in turgor pressure. It is also able to move by means of gliding, though the specific mechanism by which this is possible is not yet known.

Cyanobionts are cyanobacteria that live in symbiosis with a wide range of organisms such as terrestrial or aquatic plants; as well as, algal and fungal species. They can reside within extracellular or intracellular structures of the host. In order for a cyanobacterium to successfully form a symbiotic relationship, it must be able to exchange signals with the host, overcome defense mounted by the host, be capable of hormogonia formation, chemotaxis, heterocyst formation, as well as possess adequate resilience to reside in host tissue which may present extreme conditions, such as low oxygen levels, and/or acidic mucilage. The most well-known plant-associated cyanobionts belong to the genus Nostoc. With the ability to differentiate into several cell types that have various functions, members of the genus Nostoc have the morphological plasticity, flexibility and adaptability to adjust to a wide range of environmental conditions, contributing to its high capacity to form symbiotic relationships with other organisms. Several cyanobionts involved with fungi and marine organisms also belong to the genera Richelia, Calothrix, Synechocystis, Aphanocapsa and Anabaena, as well as the species Oscillatoria spongeliae. Although there are many documented symbioses between cyanobacteria and marine organisms, little is known about the nature of many of these symbioses. The possibility of discovering more novel symbiotic relationships is apparent from preliminary microscopic observations.

<span class="mw-page-title-main">Bacterioplankton</span> Bacterial component of the plankton that drifts in the water column

Bacterioplankton refers to the bacterial component of the plankton that drifts in the water column. The name comes from the Ancient Greek word πλανκτος, meaning "wanderer" or "drifter", and bacterium, a Latin term coined in the 19th century by Christian Gottfried Ehrenberg. They are found in both seawater and freshwater.

<i>Planktothrix</i> Genus of bacteria

Planktothrix is a diverse genus of filamentous cyanobacteria observed to amass in algal blooms in water ecosystems across the globe. Like all Oscillatoriales, Planktothrix species have no heterocysts and no akinetes. Planktothrix are unique because they have trichomes and contain gas vacuoles unlike typical planktonic organisms. Previously, some species of the taxon were grouped within the genus Oscillatoria, but recent work has defined Planktothrix as its own genus. A tremendous body of work on Planktothrix ecology and physiology has been done by Anthony E. Walsby, and the 55.6 kb microcystin synthetase gene which gives these organisms the ability to synthesize toxins has been sequenced. P. agardhii is an example of a type species of the genus. P. agardhii and P. rubescens are commonly observed in lakes of the Northern Hemisphere where they are known producers of potent hepatotoxins called microcystins.

CandidatusAtelocyanobacterium thalassa, also referred to as UCYN-A, is a diazotrophic species of cyanobacteria commonly found in measurable quantities throughout the world's oceans and some seas. Members of A. thalassa are spheroid in shape and are 1-2 μm in diameter, and provide nitrogen to ocean regions by fixing non biologically available atmospheric nitrogen into biologically available ammonium that other marine microorganisms can use.

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<i>Cyanothece</i> Genus of bacteria

Cyanothece is a genus of unicellular, diazotrophic, oxygenic photosynthesizing cyanobacteria.

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<i>Crocosphaera watsonii</i> Species of bacterium

Crocosphaera watsonii is an isolate of a species of unicellular diazotrophic marine cyanobacteria which represent less than 0.1% of the marine microbial population. They thrive in offshore, open-ocean oligotrophic regions where the waters are warmer than 24 degrees Celsius. Crocosphaera watsonii cell density can exceed 1,000 cells per milliliter within the euphotic zone; however, their growth may be limited by the concentration of phosphorus. Crocosphaera watsonii are able to contribute to the oceanic carbon and nitrogen budgets in tropical oceans due to their size, abundance, and rapid growth rate. Crocosphaera watsonii are unicellular nitrogen fixers that fix atmospheric nitrogen to ammonia during the night and contribute to new nitrogen in the oceans. They are a major source of nitrogen to open-ocean systems. Nitrogen fixation is important in the oceans as it not only allows phytoplankton to continue growing when nitrogen and ammonium are in very low supply but it also replenishes other forms of nitrogen, thus fertilizing the ocean and allowing more phytoplankton growth.

<i>Oscillatoria brevis</i> Species of bacterium

Oscillatoria brevis is a species of the genus Oscillatoria first identified in 1892. It is a blue-green filamentous cyanobacterium, which can be found in brackish and fresh waterways. O. brevis can also be isolated from soil.

Richelia is a genus of nitrogen-fixing, filamentous, heterocystous and cyanobacteria. It contains the single species Richelia intracellularis. They exist as both free-living organisms as well as symbionts within potentially up to 13 diatoms distributed throughout the global ocean. As a symbiont, Richelia can associate epiphytically and as endosymbionts within the periplasmic space between the cell membrane and cell wall of diatoms.

<span class="mw-page-title-main">Cyanobacterial morphology</span> Form and structure of a phylum

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Margaret Ruth Mulholland is professor at Old Dominion University known for her work on nutrients in marine and estuarine environments.

References

  1. 1 2 3 4 5 6 Orcutt, K. M.; Rasmussen, U.; Webb, E. A.; Waterbury, J. B.; Gundersen, K.; Bergman, B. (2002). "Characterization of Trichodesmium spp. by genetic techniques". Applied and Environmental Microbiology. 68 (5): 2236–2245. Bibcode:2002ApEnM..68.2236O. doi:10.1128/AEM.68.5.2236-2245.2002. PMC   127538 . PMID   11976093.
  2. 1 2 3 4 5 6 7 8 9 10 11 Capone, Douglas G.; Zehr, Jonathan P.; Paerl, Hans W.; Bergman, Birgitta; Carpenter, Edward J. (1997-05-23). "Trichodesmium, a Globally Significant Marine Cyanobacterium". Science. 276 (5316): 1221–1229. doi:10.1126/science.276.5316.1221. ISSN   0036-8075.
  3. 1 2 3 4 Prufert-Bebout, L; Paerl, H.W.; Lassen, C (1993). "Growth, nitrogen fixation, and spectral attenuation in cultivated Trichodesmium species". Applied and Environmental Microbiology. 59 (5): 1367–1375. Bibcode:1993ApEnM..59.1367P. doi:10.1128/aem.59.5.1367-1375.1993. PMC   182091 . PMID   16348931.
  4. ↑ Ehrenberg, C. G. (1830-01-01). "Neue Beobachlungen über blutartige Erscheinungen in Aegypten, Arabien und Sibirien, nebst einer Uebersicht und Kritik der früher bekannnten". Annalen der Physik. 94 (4): 477–514. Bibcode:1830AnP....94..477E. doi:10.1002/andp.18300940402. ISSN   1521-3889.
  5. 1 2 3 Gomont, M.A. (1892). "Essai de classification des nostocacies hom-ocysthes". Journal of Botany. 4: 355–6.
  6. ↑ Komárek, J; Anagnostidis, K (2005). Cyanoprokaryota, Part 2: Oscillatoriales, Süsswasserflora von Mitteleuropa. Springer Spektrum. ISBN   978-3-8274-1914-9.
  7. ↑ Strunecký, Otakar; Komárek, Jiří; Johansen, Jeffrey; Lukešová, Alena; Elster, Josef (2013-12-01). "Molecular and morphological criteria for revision of the genus Microcoleus (Oscillatoriales, Cyanobacteria)". Journal of Phycology. 49 (6): 1167–1180. doi: 10.1111/jpy.12128 . ISSN   1529-8817. PMID   27007635. S2CID   23185956.
  8. ↑ Wilmotte, Annick (1994-01-01). "Molecular Evolution and Taxonomy of the Cyanobacteria". In Bryant, Donald A. (ed.). The Molecular Biology of Cyanobacteria. Advances in Photosynthesis. Springer Netherlands. pp. 1–25. doi:10.1007/978-94-011-0227-8_1. ISBN   9780792332732.
  9. ↑ Komárek, J; Kaštovský, J; Mareš, J; Johansen, J.R. (2014). "Taxonomic classification of cyanoprokaryotes (cyanobacterial genera) using a polyphasic approach" (PDF). Preslia. 86: 295–335.
  10. ↑ Janson, Sven; Siddiqui, Pirzada J. A.; Walsby, Anthony E.; Romans, Kristen M.; Carpenter, Edward J.; Bergman, Birgitta (1995-06-01). "Cytomorphological Characterization of the Planktonic Diazotrophic Cyanobacteria Trichodesmium Spp. from the Indian Ocean and Caribbean and Sargasso Seas1". Journal of Phycology. 31 (3): 463–477. doi:10.1111/j.0022-3646.1995.00463.x. ISSN   1529-8817. S2CID   84908826.
  11. 1 2 3 4 Mulholland, Margaret R.; Capone, Douglas G. (2002). "The nitrogen physiology of the marine N 2-fixing cyanobacteria Trichodesmium spp". Trends in Plant Science. 5 (4): 148–153. doi:10.1016/S1360-1385(00)01576-4. PMID   10740295.
  12. ↑ Bergman, B.; Sandh, G.; Lin, S.; Larsson, J.; Carpenter, E. J. (2013). "Trichodesmium–a widespread marine cyanobacterium with unusual nitrogen fixation properties". FEMS Microbiology Reviews. 37 (3): 286–302. doi:10.1111/j.1574-6976.2012.00352.x. PMC   3655545 . PMID   22928644.
  13. ↑ Capone, D. G.; O'Neil, J. M.; Zehr, J.; Carpenter, E. J. (1990). "Basis for diel variation in nitrogenase activity in the marine planktonic cyanobacterium Trichodesmium thiebautii". Applied and Environmental Microbiology. 56 (11): 3532–3536. Bibcode:1990ApEnM..56.3532C. doi:10.1128/aem.56.11.3532-3536.1990. PMC   185016 . PMID   16348357.
  14. ↑ Walworth, N.; Pfreundt, U.; Nelson, W. C.; Mincer, T.; Heidelberg, J. F.; Fu, F.; Waterbury, J. B.; del Rio, T. G.; Goodwin, L. (2015). "Trichodesmium genome maintains abundant, widespread noncoding DNA in situ, despite oligotrophic lifestyle". Proceedings of the National Academy of Sciences. 112 (14): 4251–4256. Bibcode:2015PNAS..112.4251W. doi: 10.1073/pnas.1422332112 . PMC   4394263 . PMID   25831533.
  15. ↑ "Taxon Details". img.jgi.doe.gov. Retrieved 2017-03-26.
  16. 1 2 3 Karl, D.; Michaels, A.; Bergman, B.; Capone, D.; Carpenter, E.; Letelier, R.; Lipschultz, F.; Paerl, H.; Sigma, D. (2002). "Dinitrogen fixation in the world's oceans". The Nitrogen Cycle at Regional to Global Scales. Vol. 57/58. Springer Netherlands. pp. 47–98. doi:10.1023/A:1015798105851. JSTOR   1469685. S2CID   97226012.{{cite book}}: |journal= ignored (help)
  17. ↑ Capone, Douglas G.; Carpenter, E. J. (1982). "Nitrogen fixation in the marine environment". Science. 217 (4565): 1140–1142. Bibcode:1982Sci...217.1140C. doi:10.1126/science.217.4565.1140. PMID   17740970. S2CID   27475872.
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