Arthrospira platensis

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A Microbial Biorealm page on the genus Arthrospira platensis

Classification

Higher order taxa

Domain: Bacteria Phylum: Cyanobacteria Class: Cyanophyceae Order: Oscillatoriales Family: Phormidiaceae

Species

Genus: Arthrospira Species: platensis

Arthrospira (Spirulina) platensis; A. platensis

Description and significance

-Does not fix nitrogen(1) -Aztecs consumed regularly, thought to be important dietary element in tropical areas(1) -Alkali and salt tolerance and algal mat production along periphery of lakes(1) -Presence of hydrogenase makes it useful for clean energy production(1) -Develops cAMP-dependent signal cascades to adapt to severe environmental conditions(1)

-Consumption shown to lower blood pressure and reduce cholesterol(3) -Grown commercially as a food additive(3)

-Commercially produced as human food supplement for over 10 years(6) -High quality source of protein, vitamins, minerals, essential fatty acids, and beta-carotene(6) -Grows in carbonate-rich lakes in Torrid Zones(6)

-Fast growing, high protein content, rich in vitamins, non-toxic, well-balanced amino acid composition(2) -Used before and after drug treatment in order to remove harmful agents from organism and introduce elements/compounds that strengthen the immune system – creates favorable conditions for drugs to work at optimum level of performance(2) -Used as anti-carcinogen – used to treat radiation sickness in people affected by Chernobyl accident(2) -Maximum growth achieved in 4th or 5th day of cultivation(2) -Conditions for optimal growth: standard mineral nutrient, 30-34 deg C, pH 8.5-11, sodium light lamp(2)

-Spiral-shaped, filamentous, cyanobacterium, phototrophic, produce oxygen(5) -Grow in freshwater, alkaliphiles, saline soda lakes – high salt and pH (8-11) Example: Lake Magadi(5) -High concentration of carotenes, protein, vitamin B12, minerals, and antioxidants (prevent cancer)(5) -Filaments approximately 5μm, cells wider than they are long, produce hormongia – short, motile chains (3-5 cells)(5) -Gliding motility – poorly understood, no flagella(5) -Have carboxysomes (contain Rubisco to fix CO2), gas vesicles, and thylakoid membranes as adaptations for being phototrophic(5) -Contain lipid bacteria to store energy-rich compounds and a thick peptidoglycan cell wall (both features of all cyanobacteria)(5) -One of the rare edible bacteria because of its low purine concentration – normally, bacteria can not be part of diet because they have a higher nucleic acid component (high purines), which form uric acid – can’t be broken down by humans and forms conditions such as gout and kidney stones(5) -Main diet component for flamingos – carotenes released when bacteria digested and are deposited to feathers, producing pink color(5) -Available as a health food supplement – humans don’t turn pink because it makes up such a small portion of the diet(5) -Na+/H+ antiporters bring protons in and push Na out to drastic changes to cell pH – resistant to high salt concentration because Na is being pushed out of cells(5) -Food industry classifies as single-celled proteins, meaning edible microbes with high food value(5)

-Chlorophylls, carotenoids, and phycobiliproteins are pigments used in absorption of light(4) -Association of carotenoids and chlorophyll prevents formation of highly reactive oxygen radicals(4) -65-70% complete protein with all essential amino acids in perfect balance(4)

Genome structure

In March 2010, Arthrospira platensis became the first filamentous, non-N2-fixing cyanobacterium to have its genome sequenced and published(1). The genome consists of a single, circular chromosome and was found to be 6.8Mb in size with 44.3% G-C cotent(1). There were 6630 protein-coding genes detected, as well as 49 RNA genes, including 2 sets of rRNA genes and 40 tRNA genes(1). When looked at in its entirety, 78% of the species' genes showed similarity to genes with known function in other organisms, while 22% of the genome is made up of unknown genes(1).

Cell structure and metabolism

Interesting features of cell structure; how it gains energy; what important molecules it produces.

Ecology

Habitat; symbiosis; contributions to the environment.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Current Research

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Cool Factor

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References

1. Fujisawa, Takatomo et al. “Genomic Structure of an Economically Important Cyanobacterium, Arthrospira (Spirulina) platensis NEIS-39.” DNA Research 17 (2010): 85-103.

2. Mosulishvili, L. M., E. I. Kirkesali, A. I. Beiokobylsky, and A. I. Khizanishvili. “Experimental Substantion of the Possibility of Developing Selenium and Iodine Containing Pharmaceuticals Based on Blue-green Algae Spirulina platensis.” Journal of Pharmaceutical and Biomedical Analysis 30.1 (2002): 87-97. Web. 5 Oct. 2011.

3. National Center for Biotechnology Information. Web. 05 Oct 2011. <http://www.ncbi.nlm.nih.gov/bioproject?Db=genome&Cmd=ShowDetailView&TermToSearch=6605.>

4. Singh, Nirbhay Kumar and Dolly Wattal Dhar. “Phylogenetic Relatedness Among Spirulina and Related Cyanobacterial Genera.” World J Microbiol Biotechnol 27 (2011): 941-951.

5. Slonczewski, Joan L. and John W. Foster. Microbiology: An Evolving Science. 2nd Ed. New York: W. W. Norton & Company, Inc., 2009. 141-685.

6. Watunuki, Hironubu, Kazuki Ota, Asmi Citra Malina, A. R. Tassakka, Toshimitsu Kato, and Masahiro Sakai. “Immunostimulant Effects of Dietary Spirulina platensis on Carp, Cyprinus Carpio.” Aquaculture 258. 1-4 (2006): 157-63. Web. 5 Oct. 2011.

Edited by student of Iris Keren NEUF2011