Ohnuki Toshihiko
Institute of Human Culture Studies, Otsuma Women's University.
Institute of Innovative Research, Tokyo Institute of Technology.
Yakugaku Zasshi. 2024;144(6):651-657. doi: 10.1248/yakushi.23-00197-4.
Microbial exudates including siderophore, which changes chemical species of actinides and lanthanides. We have investigated effects of desferrioxamine B (DFOB; one of the siderophores) and siderophore-like organic molecules (SLOM) on the adsorption of lanthanides by microbial cells, aluminium oxide (AlO), and manganese (Mn) oxides. When DFOB was present, the distribution coefficients of cerium (Ce) were measured to be lower than those of neighboring elements of lanthanum (La) and praseodymium (Pr) (Negative anomaly of Ce adsorption). Even though initial oxidation state of Ce in the solution was III, that was changed to IV after the addition of DFOB, indicating that Ce(III) was oxidized by forming complex with DFOB. When lanthanides were adsorbed by biogenic Mn(IV) oxides, negative anomaly of Ce adsorption was observed in the sorption in alkaline solution. Ce(III) was oxidized to forme the complexes of Ce(IV) with SLOM in the solution. These results show that siderophore possesses high performance of oxidation of Ce(III) to Ce(IV) during association, affectiong the adsorption behavior of Ce. After Fukushima accident, radioactive Cs accumulation by Eleutherococcus sciadophylloides (Koshiabura) caused by the dissolution of Fe from soil around the roots, that was dominated by siderophore releasing microorganisms (SB). These SBs may enhance dissolution of iron (Fe) and uranium (U) phases in the nuclear fuel debris formed in the nuclear reactors in Fukushima Daiichi nuclear power plant. Thus, in the interaction between microorganisms and radionuclides, SLOMs discharged by microorganisms are deeply involved in the chemical state change of radionuclides.
微生物渗出物包括铁载体，它会改变锕系元素和镧系元素的化学形态。我们研究了去铁胺B（DFOB；一种铁载体）和类铁载体有机分子（SLOM）对微生物细胞、氧化铝（AlO）和锰（Mn）氧化物吸附镧系元素的影响。当存在DFOB时，测得铈（Ce）的分配系数低于镧（La）和镨（Pr）等相邻元素（Ce吸附的负异常）。尽管溶液中Ce的初始氧化态为III，但加入DFOB后变为IV，这表明Ce(III)通过与DFOB形成络合物而被氧化。当镧系元素被生物源Mn(IV)氧化物吸附时，在碱性溶液中的吸附过程中观察到Ce吸附的负异常。Ce(III)在溶液中被氧化形成Ce(IV)与SLOM的络合物。这些结果表明，铁载体在结合过程中具有将Ce(III)氧化为Ce(IV)的高性能，影响了Ce的吸附行为。福岛事故后，刺老芽（Koshiabura）对放射性Cs的积累是由根周围土壤中Fe的溶解引起的，这主要由释放铁载体的微生物（SB）主导。这些SBs可能会增强福岛第一核电站核反应堆中形成的核燃料碎片中铁（Fe）和铀（U）相的溶解。因此，在微生物与放射性核素的相互作用中，微生物释放的SLOMs深度参与了放射性核素的化学状态变化。
