Blue light induces arsenate uptake in the protist Thraustochytrium

The effects of light on arsenic accumulation of Thraustochytrium CHN-1 were investigated. Thraustochytrium CHN-1, when exposed to blue light from light-emitting diodes (LEDs), accumulated arsenate added to its growth medium to a much greater extent than Thraustochytrium cells exposed to fluorescent or red light, or when cultured in the dark. Arsenic compounds in Thraustochytrium CHN-1 were analyzed by high-performance liquid chromatography, with an inductively coupled plasma mass spectrometer serving as an arsenic-specific detector. Arsenate, arsenite, monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA) and arsenosugar were identified. The order of arsenic species in Thraustochytrium CHN-1 was arsenic(V)> arsenic(III)> MMAA > DMAA at an arsenic concentration of 10 mg dm(-3) in the medium in blue LED light. As it is known that blue light induces the synthesis of certain metabolites in plants and microorganisms, this indicates that the accumulation of arsenic is an active metabolic process. Copyright (C) 2005 John Wiley Sons, Ltd.