title: Root endophytic bacteria of a (137)Cs and Mn accumulator plant, Eleutherococcus sciadophylloides, increase (137)Cs and Mn desorption in the soil.
abstract: We found that root endophytes of (137)Cs accumulator plant produce siderophores, resulting in the desorption of (137)Cs from the contaminated soil collected at Fukushima, Japan. We selected an endemic Japanese deciduous tree, Eleutherococcus sciadophylloides (Franch. et Sav), that accumulates high concentrations of (137)Cs and Mn. Root endophytic bacteria were isolated from E. sciadophylloides and microbial siderophore production was evaluated via chrome azurol S (CAS) Fe and CAS Al assays. Of the 463 strains that we isolated, 107 (23.1%) produced the siderophores. Using eight strains that showed high siderophore production in our assays, we examined desorption of (137)Cs, Mn, Fe and Al by the bacterial culture filtrates from (137)Cs-contaminated soil after decomposing the soil organic matter using hydrogen peroxide. We found (137)Cs and Mn desorption concomitant with Al and Fe desorption, as well as a decrease of pH. We also detected succinic acid, a well-known siderophore, in the bacterial culture filtrates of our two root endophytic bacteria. Our results strongly suggest that the root endophytic bacteria of E. sciadophylloides produce the siderophores that enhance (137)Cs and Mn desorption in the rhizosphere, making the resulting (137)Cs and Mn ions easier for E. sciadophylloides to absorb from the rhizosphere.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennoudai, Tsukuba, 305-8572, Japan. Electronic address: yamaji.keiko.fp@u.tsukuba.ac.jp.
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamaji
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennoudai, Tsukuba, 305-8572, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nagata
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1, Tennoudai, Tsukuba, 305-8572, Japan.
authors.forename: Toshikatsu
authors.initials: T
authors.lastname: Haruma
authors.affiliation: Advanced Science Research Center, Japan Atomic Energy Agency, 4-49, Muramatsu, Tokai, Ibaraki 319-1195, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ohnuki
authors.affiliation: Graduate School of Engineering, Hokkaido University, Kita 13, Nishi 8, Kitaku, Sapporo, Hokkaido, 060-8628, Japan.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Kozaki
authors.affiliation: Graduate School of Engineering, Hokkaido University, Kita 13, Nishi 8, Kitaku, Sapporo, Hokkaido, 060-8628, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Watanabe
authors.affiliation: Faculty of Symbiotic Systems Science, Fukushima University, 1, Kanayagawa, Fukushima, 960-1296, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Nanba
mesh_terms: D000535:Aluminum / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002588:Cesium Radioisotopes / Q000378:metabolism*; D028001:Eleutherococcus / Q000378:metabolism* / Q000382:microbiology; D060026:Endophytes / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D008345:Manganese / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology*; D058441:Rhizosphere; D017262:Siderophores / Q000378:metabolism; D012990:Soil Pollutants, Radioactive / Q000378:metabolism*
chemical_list: D002588:Cesium Radioisotopes; D017262:Siderophores; D012990:Soil Pollutants, Radioactive; D008345:Manganese; D000535:Aluminum; D007501:Iron
keywords: (137)Cs desorption; CAS assay; Mn desorption; Root endophytic bacteria; Siderophore