Rate of iodine volatilization and accumulation by filamentous fungi through laboratory cultures

Five strains of basidiomycetes (Lentinula edodes, Coprinus phlyctidosporus, Hebelorna vinosophyllum, Pleurotus ostreatus and Agaricus bisporus), one strain of ascomycete (Hormoconis resinae) and six strains of imperfect fungi (Penicillium chrysogenum, Penicillium roque-fortii, Cladosporium cladosporioides, Alternaria alternata, Aspergillus niger and Aspergillus oryzae) were cultured in a liquid medium containing a radioactive iodine tracer (I-125), and were tested for their abilities to volatilize or accumulate iodine. Of the fungal strains tested, 11 strains volatilized a considerable amount of iodine, with L. edodes showing the highest volatilization rate of 3.4%. The volatile organic iodine species emitted from imperfect fungi cultures was identified as methyl iodide (CH3I)- In contrast, six fungal strains in 12 strains accumulated a considerable amount of iodine from the medium with concentration factors of more than 1.0. Among these, Alt. alternata and Cl. cladosporioides accumulated more than 40% of the iodine in their hyphae, and showed high concentration factors of 22 and 18, respectively. These results suggest that filamentous fungi have a potential to influence the mobility and speciation of iodine by volatilization and accumulation. Considering their great biomass in soils, filamentous fungi may contribute to the global circulation of stable iodine and also the long-lived radioiodine, I-129 (half-life: 1.6 x 10(7) years), released from nuclear facilities into the environment. (c) 2006 Elsevier Ltd. All rights reserved.

将5种担子菌（香菇、泡囊鬼伞、葡萄色被孢霉、平菇和双孢蘑菇）、1种子囊菌（树脂嗜热真菌）和6种半知菌（产黄青霉、娄地青霉、枝孢枝孢霉、链格孢、黑曲霉和米曲霉）在含有放射性碘示踪剂（I - 125）的液体培养基中培养，并测试它们挥发或积累碘的能力。在所测试的真菌菌株中，11种菌株挥发了大量的碘，其中香菇的挥发率最高，为3.4%。从半知菌培养物中释放出的挥发性有机碘物种被鉴定为碘甲烷（CH₃I）。相比之下，12种菌株中的6种真菌菌株从培养基中积累了大量的碘，浓缩系数大于1.0。其中，链格孢和枝孢枝孢霉在其菌丝中积累了超过40%的碘，浓缩系数分别高达22和18。这些结果表明丝状真菌具有通过挥发和积累影响碘的迁移性和形态的潜力。考虑到它们在土壤中的大量生物量，丝状真菌可能有助于稳定碘以及从核设施释放到环境中的长寿命放射性碘I - 129（半衰期：1.6×10⁷年）的全球循环。（c）2006爱思唯尔有限公司。保留所有权利。