Growth and 137 Cs uptake of four Brassica species influenced by inoculation with a plant growth-promoting rhizobacterium Bacillus pumilus in three contaminated farmlands in Fukushima prefecture, Japan Han Phyo Aung a , Salem Djedidi c , Aung Zaw Oo c , Yi Swe Aye b , Tadashi Yokoyama c , Sohzoh Suzuki c , Hitoshi Sekimoto d , Sonoko Dorothea Bellingrath-Kimura c, ⁎ a United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu, Tokyo 183-8509, Japan b Department of International Environmental and Agricultural Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu, Tokyo 183-8509, Japan c Institute of Agriculture, Tokyo University of Agriculture and Technology, Saiwaicho 3-5-8, Fuchu, Tokyo 183-8509, Japan d Faculty of Agriculture, Utsunomiya University, 321-8505, Japan HIGHLIGHTS • PGPR inoculation did not enhance plant biomass of tested plants. • PGPR inoculation resulted in higher 137 Cs concentration in plants. • Komatsuna that had larger root volume showed higher 137 Cs TF from soil to plants. • Soil with high SOM and Al-vermiculite caused larger 137 Cs transfer to plants. abstract article info Article history: Received 30 December 2014 Received in revised form 23 March 2015 Accepted 25 March 2015 Available online 2 April 2015 Editor: Charlotte Poschenrieder Keywords: Radiocesium Bacillus pumilus Brassica species Transfer factor Fukushima The effectiveness of the plant growth-promoting rhizobacterium Bacillus pumilus regarding growth promotion and radiocesium ( 137 Cs) uptake was evaluated in four Brassica species grown on different 137 Cs contaminated farmlands at Fukushima prefecture in Japan from June to August 2012. B. pumilus inoculation did not enhance growth in any of the plants, although it resulted in a significant increase of 137 Cs concentration and higher 137 Cs transfer from the soil to plants. The Brassica species exhibited different 137 Cs uptake abilities in the order Komatsuna N turnip N mustard N radish. TF values of 137 Cs ranged from 0.018 to 0.069 for all vegetables. Komatsuna possessed the largest root surface area and root volume, and showed a higher 137 Cs concentration in plant tissue and higher 137 Cs TF values (0.060) than the other vegetables. Higher 137 Cs transfer to plants was prominent in soil with a high amount of organic matter and an Al-vermiculite clay mineral type. © 2015 Elsevier B.V. All rights reserved. 1. Introduction The Fukushima Daiichi nuclear power plant (FDNPP) accident trig- gered by a catastrophic earthquake (9.0 M) and the resulting tsunami in Fukushima Prefecture on 11 March, 2011 released a massive amount of radioactive nuclides into the atmospheric environment of Japan. Ra- dioactive air plumes then caused serious contamination of large ecosystems including agricultural farmlands. Radiocesium ( 137 Cs) is one of the major radionuclides and imposes a considerable environ- mental threat because of its high relative mobility in the soil–plant sys- tem, long-term bioavailability, high radiotoxicity and relatively long half-life (30.17 yrs.) (Rahman and Voitgt, 2004). The entry of 137 Cs into plants is strongly dependent on plant species and its adsorption onto soil (Staunton and Levacic, 1999). Uptake of 137 Cs by plant roots is the main pathway for the migration of 137 Cs from soil to humans via plants. The ability of plants to take up 137 Cs is usually represented by the transfer factor (TF) expressed as the ratio of 137 Cs concentration in plant tissues to that in the soil. It is used widely to predict the concentration of radionuclides in agricultural crops and Science of the Total Environment 521–522 (2015) 261–269 ⁎ Corresponding author at: Tokyo University of Agriculture and Technology, Graduate School of Agriculture, Department of International Environmental and Agricultural Science, Saiwaicho 3-5-8, Fuchu, Tokyo 183-8509, Japan. E-mail address: skimura@cc.tuat.ac.jp (S.D. Bellingrath-Kimura). http://dx.doi.org/10.1016/j.scitotenv.2015.03.109 0048-9697/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv