Trichodesmium thiebautii
Classification
Higher order taxa
Bacteria; Cyanobacteria; Cyanophyceae; Oscillatoriales; Microcoleaceae; Trichodesmium
Species
Trichodesmium thiebautii
Description and Significance
Trichodesmium thiebautii was named and first described by M. Gomont in a paper published in 1892 (1). T. thiebautii is a gram-negative, coccus shaped marine cyanobacteria. T. thiebautii prefers warmer temperatures and has been found in tropical and subtropical oceans (9). T. thiebautii has been hard to study and does not have extensive research. Maintaining living cultures has been difficult. The longest any culture has survived is three months (5). T. thiebautii forms colonies. They have been found in the shape of fusiform and radial colonies. Fusiform colonies are the most abundant type. The T. thiebautii fusiform colonies are twisted like a rope (4). T. thiebautii has non-constricted trichomes surrounding the outside of its cell. The morphology of trichomes is similar within a colony, but varies between each different, separate colony (4,9). T. thiebautii are non-heterocystous and fix nitrogen gas. It fixes nitrogen gas during the day, which is unlike other cyanobacteria (3).
Genome and genetics
T. thiebautii’s genome has been sequenced using whole genome shotgun sequencing. The whole genome shotgun sequence can be found on the National Center for Biotechnology Information website with the following link: https://www.ncbi.nlm.nih.gov/nuccore/LAMW01000047.1. The total length of its genome is about 3.29 Mb with 35.4 %GC (15). It consists of about 39,217 base pairs (13). T. thiebautii has 3,370 genes (14). An important gene that T. thiebautii have are nifH genes. These genes are incredibly important because they produce nitrogen fixation proteins (nifH) (16). T. thiebautii belong to the bacteria branch of prokaryotes (6). The genus that Trichodesmium, including T. thiebautii, are most closely related to are Oscillatoria sancta PCC 7515 (6). All of the species within the Trichodesmium genus are closely related. The species that is the most genetically different from T. thiebautii and the others is T. erythraeum. There are two different clades of Trichodesmium species. One clade includes T. thiebautii, along with T. tenue, T. hildebrandtii, and K. spiralis. The other clade only includes T. erythraeum (11).
Nutrition and metabolism
T. thiebautii are gram-negative, coccus shaped bacteria. They are primary producers. Phosphorus, iron, and physical forcing are believed to limit the growth of Trichodesmiums (17). Trichodesmium need 10 times as much iron than cyanobacteria that don’t fix nitrogen. Trichodesmium find most, if not all, of their iron in the open ocean from “aeolian-transported” particles. Trichodesmium also need O2. The nitrogenase in natural colonies are sensitive to O2. There is an O2 requirement under certain conditions. Trichodesmium colonies only take in 15NO3 in the evening or at night. They also only take in 15NH4+ at night. Trichodesmiums prefer to get their nitrogen from urea. Trichodesmium blooms are formed due to different factors, such as “physical stability, high pH, and colony shape” (10). T. thiebautii divide by binary fission and in one plane (6). The most important product of T. thiebautii is new nitrogen. Trichodesmiums produce the largest amount of new nitrogen to the euphotic zone of the ocean (10). Trichodesmium species are tricky when it comes to culturing them. Many scientists have had trouble growing cultures of any of the Trichodesmium species. Rueter and Annete Hynes have both encountered problems while attempting to culture a Trichodesmium species (4, 8). Others have successfully cultured Trichodesmiums. Scientists have successfully cultured a Trichodesmium from Japan on a modified version of the defined medium “Aquil”. A Trichodesmium species was cultured on a medium with a seawater base in North Carolina (6).
Ecology / Pathology
T. thiebautii is a marine cyanobacteria. It is one of the two most common Trichodesmium species. It has been found in tropical, subtropical, and temperate waters at depths of 450 feet (8, 12). It has the ability to form massive seasonal blooms that expand kilometers of ocean. It is a major part of the marine primary production and the global nitrogen cycle (12). It is important because it fixes nitrogen in the ocean. Scientists believe that the nitrogen produced by Trichodesmium blooms helps initiate the blooms of other bacteria. They claim that a part of the nitrogen required for the start of karenia brevis blooms comes from the nitrogen produced be Trichodesmiums (2). All Trichodesmiums are different from other nonheterocystous diazotrophic cyanobacteria because they can fix nitrogen during the day and night. Their nitrogen fixation and photosynthesis occur at the same time, even though they seem as if they would conflict with each other (6, 18). Although the nitrogen from T. thiebautii is good, the bacteria species itself has been classified as toxic (12). Trichophycin A, a cytotoxin isolated from a T. thiebautii bloom, has shown cytotoxicity against Neuro-2A murine neuroblastoma cells and HCT-166 human colon cancer cells (2). Another cytotoxin present in T. thiebautii are trichotoxins (12). In several laboratories, T. thiebautii has shown neurotoxic effects. The two known toxic Trichodesmium species, one being T. thiebautii, have been the assumed cause of death of several marine mammals. The deaths of several marine animals, such as fish, oysters, and crabs have been linked to T. thiebautii. It has also killed different types of copepods and brine shrimp (12). Hundreds of Brazilians were diagnosed with Tamandare Fever in 1963. They experienced respiratory problems, fevers, muscle pains, and rashes on their chests and arms. The Tamandare Fever was the first and only reported human illness associated with any Trichodesmium species. Some scientists claim that have had “respiratory distress” and “contact dermatitis” when working with T. thiebautii (12).
Current Research
Describe recent research and findings that have been done with this organism. The research can be clinical, applied or basic research. This section should be based on 2 recent papers (10 years or less) and summarized in your own words.
References
1. Bergman, B., Carpenter, E. J., Larsson, J., Lin, S., Sandh, G. “Trichodesmium – a widespread marine cyanobacterium with unusual nitrogen fixation properties”. FEMS Microbial Rev. 2013 May; 37(3): 286-302 [PubMed] 2. Capone, D. G., Ferrier, M. D., Carpenter, E. J. “Amino Acid Cycling in Colonies of the Planktonic Marine Cyanobacterium Trichodesmium thiebautii”. Applied and Environmental Microbiology, Nov. 1994, p. 3989-3995. 3. Carpenter, E. J., McCarthy, J. J., Rueter, J. G. 1979. “The toxic effect of copper on Oscillatoria (Trichodesmium) theibautii”. Limnol. Oceanogr., 24(3):558-562. 4. Carpenter, E. J., Capone, D. G., Rueter, J. G. “Marine Pelagic Cyanobacteria: Trichodesmium and other Diazotrophs”. 1991. NATO ASI Series. Series C: Mathematical and Physical Sciences – Vol. 362. 5. Monteiro, J., Leca, E., Koening, M., Macedo, S. “New record of Trichodesmium thiebautii Gomont ex Gomont (Oscillatoriales – Cyanophyta) for the continental shelf of northeastern Brazil”. Acta Bot. Bras. vol.24 no.4 Feira de Santana Oct./Dec. 2010
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