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Soil Biology & Biochemistry 38 (2006) 2882–2889 www.elsevier.com/locate/soilbio

Bacterial inoculants affecting nickel uptake by Alyssum murale from low, moderate and high Ni soils
R.A.I. Abou-Shanaba,Ã, J.S. Angleb, R.L. Chaneyc b Department of Natural Resources Sciences, University of Maryland, College Park, 20742, USA College of Agriculture and Environmental Sciences, University of Georgia, Athens, GA 30602, USA c USDA-ARS, EMBUL, Beltsville, MD 20705, USA Received 4 February 2006; received in revised form 20 April 2006; accepted 26 April 2006 Available online 24 May 2006

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Abstract Metal hyperaccumulator plants like Alyssum murale have a remarkable ability to hyperaccumulate Ni from soils containing mostly insoluble Ni. We have shown some rhizobacteria increase the phytoavailability of Ni in soils, thus enhancing Ni accumulation by A. murale. Nine bacterial strains, originally isolated from the rhizosphere of A. murale grown in serpentine Ni-rich soil, were examined for their ability to solubilize Ni in different soils and for their effect on Ni uptake into Alyssum. Microbacterium oxydans AY509223; Rhizobium galegae AY509213; Microbacterium oxydans AY509219; Clavibacter xyli AY509236; Acidovorax avenae AY512827; Microbacterium arabinogalactanolyticum AY509225; M. oxydans AY509222; M. arabinogalactanolyticum AY509226 and M. oxydans AY509221 were added to low, moderate and high Ni-contaminated soils. M. oxydans AY509223 significantly increased Ni extraction by 10 mM Sr(NO3)2 from the high and medium soils and had no effect on Ni extraction from the low Ni soils. The other eight bacterial isolates significantly increased Ni extraction from all soils. There were no significant effects of bacterial inoculation on fresh and dry weight of A . murale shoots grown in the low and high Ni soils compared to an unamended control. M. oxydans AY509223 significantly increased Ni uptake of A. murale grown in the low, medium, and high soils by 36.1%,