Large quantities of radionuclides have leaked from the Fukushima Daiichi Nuclear Power Plant into the surrounding
environment. Effective prevention of health hazards resulting from radiation exposure will require the development of
efficient and economical methods for decontaminating radioactive wastewater and aquatic ecosystems. Here we describe
the accumulation of water-soluble radionuclides released by nuclear reactors by a novel strain of alga. The newly discovered
green microalgae, Parachlorella sp. binos (Binos) has a thick alginate-containing extracellular matrix and abundant
chloroplasts. When this strain was cultured with radioiodine, a light-dependent uptake of radioiodine was observed. In dark
conditions, radioiodine uptake was induced by addition of hydrogen superoxide. High-resolution secondary ion mass
spectrometry (SIMS) showed a localization of accumulated iodine in the cytosol. This alga also exhibited highly efficient
incorporation of the radioactive isotopes strontium and cesium in a light-independent manner. SIMS analysis showed that
strontium was distributed in the extracellular matrix of Binos. Finally we also showed the ability of this strain to accumulate
radioactive nuclides from water and soil samples collected from a heavily contaminated area in Fukushima. Our results
demonstrate that Binos could be applied to the decontamination of iodine, strontium and cesium radioisotopes, which are
most commonly encountered after nuclear reactor accidents.