Candidatus gloeomargarita lithophora: Difference between revisions

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[[File:Candidatus_Gloeomargarita_lithophora.jpg|thumb|500px|Magnified view of <I>Candidatus Gloeomargarita lithophora</I> and biomineralizations<sup>[2]</sup>]]
[[File:Candidatus_Gloeomargarita_lithophora.jpg|thumb|500px|Magnified view of <I>Candidatus Gloeomargarita lithophora</I> and biomineralizations<sup>[2]</sup>]]
==Description and significance==
==Description and significance==
<I>Candidatus</I> Gloeomargarita lithophora, a [http://en.wikipedia.org/wiki/Cyanobacteria cyanobacterium], was found growing in colonies at the bottom of a lake in Mexico in 2012. This microbe can actively transport elements such as strontium, barium, magnesium, and calcium into the cell from the environment and incorporate them into granules, which increases the density of the cell and helps to keep the bacterium anchored at the bottom of the lake. <I>Ca.</I>G. lithophora is the first bacterium shown to produce internal [http://en.wikipedia.org/wiki/Biomineralization biomineralizations],<sup>[2]</sup> as opposed to other cyanobacteria which can precipitate minerals out of the cell.<sup>[3]</sup> The mechanism for this biomineralization is still unknown, but it is believed that since the microbe is such an ancient species, the mechanism for transporting minerals outside of the cell had not evolved yet.<sup>[2]</sup> It is hypothesized that internal mineralization by this ancient order of cyanobacteria could help explain the lack of fossils from the early origins of cyanobacteria about 2.7 billion years ago, as evidenced by atmospheric oxygen levels, to the earliest fossil evidence of cyanobacteria about 1.2 billion years ago. <sup>[4]</sup>  
<I>Candidatus</I> Gloeomargarita lithophora, a [http://en.wikipedia.org/wiki/Cyanobacteria cyanobacterium], was found growing associated to [https://en.wikipedia.org/wiki/Stromatolite microbialites] in an alkaline lake in Mexico in 2012. This microbe control the formation of intracellular carbonate granules. <I>Ca.</I>G. lithophora is the first bacterium shown to produce internal [http://en.wikipedia.org/wiki/Biomineralization biomineralizations],<sup>[2]</sup> as opposed to some other cyanobacteria which can precipitate minerals out of the cell.<sup>[3]</sup> The ability of intracellular calcification has recently been extended to other members of the Cyanobacteria <sup>[5]</sup>. The mechanism for this biomineralization is still unknown, but it is possible that this mechanism is ancient in the cyanobacterial lineage.<sup>[2]</sup> It is hypothesized that internal mineralized granules are not likely to get preserved after the cell death, indeed these particles have never been observed outside of the cell. This observation could help explain the lack of microfossils from the early origins of cyanobacteria about 2.7 billion years ago, as evidenced by atmospheric oxygen levels, to the earliest fossil evidence of cyanobacteria about 1.2 billion years ago. <sup>[4]</sup>


==Genome structure==
==Genome structure==

Revision as of 20:48, 23 July 2015

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A Microbial Biorealm page on the genus Candidatus gloeomargarita lithophora

Classification

Higher order taxa

Domain (Bacteria); Phylum (Cyanobacteria); Class (Gloeobacteria); Order (Gloeobacterales); Genus (Candidatus Gloeomargarita)[1]

Species

Species (lithophora)

Candidatus Gloeomargarita lithophora

Magnified view of Candidatus Gloeomargarita lithophora and biomineralizations[2]

Description and significance

Candidatus Gloeomargarita lithophora, a cyanobacterium, was found growing associated to microbialites in an alkaline lake in Mexico in 2012. This microbe control the formation of intracellular carbonate granules. Ca.G. lithophora is the first bacterium shown to produce internal biomineralizations,[2] as opposed to some other cyanobacteria which can precipitate minerals out of the cell.[3] The ability of intracellular calcification has recently been extended to other members of the Cyanobacteria [5]. The mechanism for this biomineralization is still unknown, but it is possible that this mechanism is ancient in the cyanobacterial lineage.[2] It is hypothesized that internal mineralized granules are not likely to get preserved after the cell death, indeed these particles have never been observed outside of the cell. This observation could help explain the lack of microfossils from the early origins of cyanobacteria about 2.7 billion years ago, as evidenced by atmospheric oxygen levels, to the earliest fossil evidence of cyanobacteria about 1.2 billion years ago. [4]

Genome structure

A genetic analysis of similar bacteria in the Gloeobacter genus found several genes involved in photosynthesis were missing. The bacteria in this genus do not contain a thylakoid membrane, and therefore do not have more advanced structures involved in photosynthesis that are found in other photosynthetic bacteria. This indicates that Gloeobacter is one of the oldest photosynthetic bacteria. The genome for Candidatus Gloeomargarita lithophora has not yet been studied, but a related microbe, Gloeobacter violaceus, has a single circular chromosome with no plasmid.[5]

Cell and colony structure

Candidatus Gloeomargarita lithophora is a rod-shaped, unicellular microbe measuring about 4 μm long and 1 μm wide. These cells contain around 20 spherical granules within the cytoplasm, each measuring about 270 nm in diameter; these granules comprise roughly 6% of the cell's volume and increase the density of the cell by 12%.This species is also capable of forming biofilms[2]

Lake Alchichica, Mexico.[6]

Metabolism

Candidatus Gloeomargarita lithophora uses light as an energy source like other cyanobacteria, but unlike other cyanobacteria does not contain thylakoids. A proton gradient forms along the plasma membrane, where phycobilisomes, light harvesting structures, are attached to the cytoplasmic side. Ca.G. lithophora uses water as an electron donor and produces oxygen as a byproduct of photosynthesis. [5]


Ecology

To date, this microbe has only been found living in shallow water of a freshwater lake, and was later isolated in a lab. As a cyanobacterium, Candidatus Gloeomargarita lithophora is important in oxygen production and carbon fixation. The use of strontium by the cell may lead to the use of the bacterium in remediation of nuclear contamination. [4] Lake Alchichica is a highly alkaline lake, with an average pH of about 8.9. It is possible that in internal mineralizations formed by Ca.G. lithophora act as a type of buffer in response to the high pH. The mineralizations may also act as an anchor, allowing the microbe to enter the water column and settle back down to the surface when needed.[2]


Future Research

Future research into Candidatus Gloeomargarita lithophora may focus on the optimal growth conditions of the microbe, as well as studying its genome.[2] Another question that needs to be looked at is whether the biomineralizations disintegrate after the cell dies. If this is the case, it may help to explain a lack of fossil evidence for these types of microbes.[4]


References

[1] ["Taxonomy Browser." NCBI. U.S. National Library of Medicine, n.d. Web. 9 Mar. 2013. <http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info>.]

[2] [Couradeau, E., Benzerara, K., Gérard, E., Moreira, D., Bernard,S., Brown Jr., G.E., and López-García, P. “An Early-Branching Microbialite Cyanobacterium Forms Intracellular Carbonates,” Science 336 (2012), 459. DOI: 10.1126/science.1216171]

[3] [Power, I., Wilson, S., Thom, J., Dipple, G., and Southam, G. "Biologically Induced Mineralization of Dypingite by Cyanobacteria from an Alkaline Wetland near Atlin, British Columbia, Canada." Geochemical Transactions 8.1 (2007): 13. Print. doi:10.1186/1467-4866-8-13]

[4] [Riding, R. "A Hard Life for Cyanobacteria." Science 336 (2012): 427. DOI: 10.1126/science.1221055]

[5] [Nakamura, Y., Kaneko, T., Sato, S. et al. "Complete genome structure of Gloeobacter violaceus PCC 7421, a cyanobacterium that lacks thylakoids". DNA Res. 10 (4): 137–45 (2003)DOI: 10.1093/dnares/10.4.137.]

[6] [ROV, Veronica. "Photos." Alchichica Lake, a Photo from Veracruz, Gulf. TrekEarth, 03 June 2007. Web. 25 Apr. 2013. http://www.trekearth.com/gallery/North_America/Mexico/Gulf/Veracruz/Perote/photo663669.htm]


Edited by Andy Nichols, student of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio