Arthrospira maxima

Genome Structure

Arthrospira maxima has a genome size of 5.4 Mb or 5,400,000 base pairs. The entire genome has been sequenced and is available through the Departments of Energy’s Joint Genome Institute in raw form. Only a portion of the entire genome has been analyzed. Genes that were involved in DNA replication, repair, modification, transcription and translation were identified. Most of the genes sequenced were involved with DNA replication and repair. Many genes that were involved in energy metabolism were identified. Some important sequences encoding gas vacuole proteins, so the bacteria can remain in the photic zone, were identified. Photosystem encoding genes were identified as well. Genes that encoded proteins for nutrient transport and circadian rhythms were also identified. There were 252 genes, that likely coded for protein, whose function could not be readily identified. It is possible that these gene sequences are unique to Arthrospira maxima.

Ecology

Arthrospira maxima are found in tropical and subtropical regions where there are warm bodies of water with high ph, carbonate, and salinity levels. It is common in soda lakes of the Rift Valley, in Africa, and Mexico. The organism has been collected and used as food for hundreds of years. It is consumed because of its high protein and nutrient content. The annual production of Arthrospira maxima and close relatives is estimated to be 3,000 tons. Arthrospira maxima can tolerate high levels of bicarbonate, carbonate, salinity and pH. It has been observed in water with a pH as high as 11. The species can reach very high cell densities. In a laboratory culture the density has been recorded at 3g dry weight per liter. In Africa, A. maxima serve as a food source for filter feeding flamingoes in soda lakes. The carotenoids in A. maxima give the birds their pink color.

Current Research

The use of cyanobacteria to produce hydrogen and oxygen from solar radiation is a promising, new technology for the production non-fossil fuel based energy. Biologically produced fuel is gaining popularity as fossil fuels are becoming more expensive and scarce. Arthrospira maxima ferments carbon compounds in the absence of light to produce hydrogen. This process is carried out in part by the hydrogenase enzyme which requires iron and nickel to operate. The rate of hydrogen production can be increased by raising the Nickel concentration. A. maxima’s is very promising because it is easy to culture, can achieve high cell densities and can produce hydrogen efficiently.

References

Ananyev G., D. Carrieri, G. C. Dismukes. 2008. Optimization of Metabolic Capacity and Flux through Environmental Cues To Maximize Hydrogen Production by the Cyanobacterium “Arthrospira (Spirulina) maxima”. APPLIED AND ENVIRONMENTAL MICROBIOLOGY 74:19 p. 6102–6113

Arthrospira maxima CS-328. April 2009. Joint Genome Instutite; US Department of Energy. <genome.jgi-psf.org/draft_microbes/artma/artma.info.html>

Carrieria D., G. Ananyeva, A. M. Garcia Costasb, D. A. Bryantb, G. C. Dismukes. 2008. Renewable hydrogen production by cyanobacteria: Nickel requirements for optimal hydrogenase activity. INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 33:2014 – 2022.

Ling N., Y. Mao, X. Zhang, Z. Mo, G. Wang, W. Liu. 2007. Sequence analysis of Arthrospira maxima based on fosmid library. Journal of Appl Phycol 19:333–346

Mühling M., P. J. Somerfield, N. Harris, A. Belay, B. A. Whitton. 2006. Phenotypic analysis of Arthrospira (Spirulina) strains (cyanobacteria). Phycologia 45: 2, 148-157.

Kruse O., J. Rupprecht, J. H. Mussgnug, G. C. Dismuke, B. Hankamer. 2005. Photosynthesis: a blueprint for solar energy capture and biohydrogen production technologies. Photochem Photobiol Sci 4: 957–969