Accumulation of arsenic by Traustochytrium sp. CHN‐1 from Seto Inland Sea

The accumulation of arsenic by Traustochytrium sp. CHN‐1 ( Labyrinthulids ) was examined by using a medium [2% (w/v) glucose, 0.1% (w/v) yeast extract, 0.1% (w/v) peptone in a half salt concentration of sea water] containing arsenic as As(V), As(III). Traustochytrium sp. CHN‐1 was grown in 1/2 sea water medium [2% (w/v) glucose, 0.1% (w/v) yeast extract, 0.1% (w/v) peptone] containing an arsenate (As(V)) at up to 1000 mg dm −3 and arsenite (As(III)) at up to 50 mg dm 3 . The cells died even at [As(III)]‐100 mg dm −3 . These results suggested that the order of growth inhibition of Traustochytrium sp. CHN‐1 by arsenic was As(III) > As(V). The biomass of Traustochytrium sp. CHN‐1 decreased with an increase of the surrounding arsenic concentration. On the other hand, the arsenic concentration in cells increased with an increase of the surrounding arsenic concentration. Arsenic compounds were extracted with methanol/water (1:1) from a freeze‐dried sample of Traustochytrium sp. CHN‐1. The extracts were analyzed by high‐performance liquid chromatography, with an inductively coupled plasma mass spectrometer serving as an arsenic‐specific detector. Arsenite, arsenate, monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA) and arsenosugar were identified in Traustochytrium sp. CHN‐1. The order of arsenic species in Traustochytrium sp. CHN‐1 was As(V) > DMAA > As(III) > MMAA > arsenosugar at [As]‐10 mg dm −3 in the medium. Detoxification of arsenic by cells was probably achieved by methylation.