Autor(es):
Rajkumar, Mani 
; Ma, Ying ; Freitas, H.
Data: 2013
Identificador Persistente: http://hdl.handle.net/10316/25636
Origem: Estudo Geral - Universidade de Coimbra
Assunto(s): Metal-resistant bacteria; Phytostabilization; Nickel; Brassica juncea; Bacillus megaterium; Luffa cylindrica; Sorghum halepense
Descrição
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).
