Arsenic compounds algae

Marine algae transform arsenate into nonvolatile methylated arsenic compounds such as methanearsonic and dimethylarsinic acids (Tamaki and Frankenberger 1992). Freshwater algae and macrophytes, like marine algae, synthesize lipid-soluble arsenic compounds and do not produce volatile methylarsines. Terrestrial plants preferentially accumulate arsenate over arsenite by a factor of about 4. Phosphate inhibits arsenate uptake by plants, but not the reverse. The mode of toxicity of arsenate in plants is to partially block protein synthesis and interfere with protein phosphorylation — a process that is prevented by phosphate (Tamaki and Frankenberger 1992). 

The later observation of Morita and Shibata (19) is relevant here. They examined the distribution of the various arsenic compounds in Hizikia fusiforme (this alga is unusual in that it contains about 50% of its total arsenic as arsenate). The total arsenic concentrations were higher at the surface layers than in the center of the alga. Arsenate... 

Aridreae, M. O., and Klumpp, D. (1979). Biosynthesis and release of organo-arsenic compounds by marine algae. Environ. Sci. Technol. 13, 738-741. 

Cullen, W.R., Harrison, L.G., Li, H. and Hewitt, G. (1994) Bioaccumulation and excretion of arsenic compounds by a marine unicellular alga, Polyphsa peniculus. Appl. Otganomet. Chem., 8, 313—324. 

T. Raise, Y. Oya-Ohta, T. Ochi, T. Okubo, R. Hanaoka, R. J. Irgolic, T. Sakurai, C. Matsubara, Toxicological study of organic arsenic compound in marine algae using mammalian cell culture techniques, J. Food Hyg. Soc. Jap., 37 (1996), 135-141. 

D. Kuehnelt, K. Irgolic, W. Goessler, Comparison of three methods for the extraction of arsenic compounds from the NRCC standard reference material DORM-2 and the brown alga Hijiki fuziforme, Appl. Organomet. Chem., 15 (2001), 445-456. 

S. McSheehy, J. Szpunar, Speciation of arsenic compounds in edible algae by bidi-mensional size-exclusion anion-exchange HPLC with dual ICP-Ms and electrospray MS/MS detection, J. Anal. Atom. Spectrom., 15 (2000), 79- 87. 

Some studies attempted further characterization of the arsenic compounds in algae [137], which involved the growth of microalgae, Tetraselmis chuii [138], Chaetoceros concavicornis [139] in media containing radiolabeled arsenate. 

Bacterial demethylation of methylarsenicals is known to occur in aerobic aqueous and terrestrial environments, giving rise to CO2 and arsenate. Common soil bacteria, such as Mycobacterium, Alcaligenes, and Pseudomonas, are known to demethylate mono- and dimethylarsenic compounds. An important part of the biogeological cycling of arsenic involves bacterial demethylation of methylarsenic acids excreted by marine algae, although the mechanism(s) of demethylation of methylated arsenic compounds is essentially unknown. 

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