Premium
Methylation of inorganic arsenic by arsenic‐tolerant freshwater algae
Author(s) -
Maeda Shigeru,
Wada Hiroshi,
Kumeda Kosuke,
Onoue Miyuki,
Ohki Akira,
Higashi Shiro,
Takeshita Toshio
Publication year - 1987
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.590010512
Subject(s) - arsenic , chemistry , biotransformation , algae , organic chemistry , inorganic chemistry , botany , enzyme , biology
Five arsenic‐resistant freshwater algae which had been isolated from an arsenic‐polluted environment were studied for the biotransformation of arsenic compounds accumulated by them from the aqueous phase. The algal cells bioaccumulating arsenic were digested by 2 mol dm −3 NaOH at 95°C, the AsC bonds except for AsCH 3 were cleaved by the treatment and the methylated arsenic compounds were reduced to the corresponding arsines by sodium borohydride (hydride generation). The arsines were chromatographically separated on the basis of their boiling‐point difference and determined by atomic absorption spectrophotometry. Methylated arsenic compounds were found in all algal cells. The predominant arsenic species in the cells, however, were non‐methylated arsenic compounds which were mainly present in the residue of a chloroform–methanol extract. The non‐methylated arsenic compounds were found to be not present in the free inorganic arsenic substrate and to be bound strongly with proteins or polysaccharides in the cells. Methylated arsenic compounds were found mainly in the lipid‐soluble fractions and the major form was a dimethylarsenic compound. Trimethyl‐ and monomethyl‐arsenic compounds were detected but at very low level. The dimethylarsinic acid was not present in the free form in the lipid‐soluble fraction and should be bound with a lipid molecule. It was also found that the accumulation of arsenic by Nostoc occurred only in living cells.