Suchergebnisse

The use of metal tolerant plants for the phytostabilization of metal contaminated soil is an area of extensive research and development. In this study the effects of inoculation of Ni-resistant bacterial strains on phytostabilization potential of various plants, including Brassica juncea, Luffa cylindrica and Sorghum halepense, were studied. A Ni-resistant bacterial strain SR28C was isolated from a nickel rich serpentine soil and identified as Bacillus megaterium based on the morphological features, biochemical characteristics and partial 16S rDNA sequence analysis. The strain SR28C tolerated concentrations up to 1200 mg Ni L 1 on a LuriaeBertani (LB) agar medium. Besides, it showed high degree of resistance to various metals (Cu, Zn, Cd, Pb and Cr) and antibiotics (ampicillin, tetracycline, streptomycin, chloramphenicol, penicillin and kanamycin) tested. In addition, the strain bound considerable amounts of Ni in their resting cells. Besides, the strain exhibited the plant growth promoting traits, such as solubilization of phosphate and production of indole-3-acetic acid (IAA) in modified Pikovskayas medium and LB medium, respectively in the absence and presence of Ni. Considering such potential, the effects of SR28C on the growth and Ni accumulation of B. juncea, L. cylindrica and S. halepense, were assessed with different concentrations of Ni in soil. Inoculation of SR28C stimulated the biomass of the test plants grown in both Ni contaminated and non-contaminated soils. Further, SR28C alleviated the detrimental effects of Ni by reducing its uptake and translocation to the plants. This study suggested that the PGPB inoculant due to its intrinsic abilities of growth promotion and attenuation of the toxic effects of Ni could be exploited for phytostabilization of Ni contaminated site. ; M. Rajkumar acknowledges the financial support received in the form of Ramalingaswami re-entry fellowship from Department of Biotechnology (DBT), Government of India. Y. Ma thankfully acknowledges the Portuguese Foundation for Science and Technology (FCT) for awarding a post-doctoral research grant (SFRH/BPD/ 76028/2011).

The aim of this study was to investigate the effects of metal mobilizing plant-growth beneficial bacterium Phyllobacterium myrsinacearum RC6b on plant growth and Cd, Zn and Pb uptake by Sedum plumbizincicola under laboratory conditions. Among a collection of metal-resistant bacteria, P. myrsinacearum RC6b was specifically chosen as a most favorable metal mobilizer based on its capability of mobilizing high concentrations of Cd, Zn and Pb in soils. P. myrsinacearum RC6b exhibited a high degree of resistance to Cd (350 mg L 1), Zn (1000 mg L 1) and Pb (1200 mg L 1). Furthermore, P. myrsinacearum RC6b showed multiple plant growth beneficial features including the production of 1-aminocyclopropane-1-carboxylic acid deaminase, indole-3-acetic acid, siderophore and solubilization of insoluble phosphate. Inoculation of P. myrsinacearum RC6b significantly increased S. plumbizincicola growth and organ metal concentrations except Pb, which concentration was lower in root and stem of inoculated plants. The results suggest that the metal mobilizing P. myrsinacearum RC6b could be used as an effective inoculant for the improvement of phytoremediation in multi-metal polluted soils. ; Y. Ma thankfully acknowledges the Portuguese Foundation for Science and Technology (FCT) for awarding a post-doctoral research grant (SFRH/BPD/76028/2011). M. Rajkumar acknowledges the financial support received in the form of Ramalingaswami re-entry fellowship from Department of Biotechnology (DBT), Government of India.