Improvement of Ni phytostabilization by inoculation of Ni resistant Bacillus megaterium SR28C

Abstract

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 Luria-Bertani (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.

Inoculation with Metal-Mobilizing Plant-Growth-Promoting RhizobacteriumBacillussp. SC2b and Its Role in Rhizoremediation

“…2011b), and copper (Cu) (Zhang et al, 2011). In some cases, increased growth and tolerance against heavy metal stress observed in PGPB inoculated plants have been explained by plant beneficial traits of PGPB and/or reduced metal uptake by plants (Rajkumar et al, 2013). However, different PGPB-hyperaccumulator associations might provide different responses, and therefore, further research is required to understand whether PGPB-inoculated plants and specific strains favor rhizoremediation of pollutants and through which mechanisms.…”

“…Although several recent investigations addressed rhizosphere and endophytic microbial population of plants and their role on rhizoremediation in metal-polluted soils (Ma et al, 2011b;Rajkumar et al, 2013), the beneficial interactions between S. plumbizincicola and PGPB and their possible role on the rhizoremediation of multi-metal-polluted agricultural soils still remain poorly understood. The objectives of this study were to (i) isolate and characterize a beneficial bacterial strain possessing the ability to mobilize metals in soils,…”

Production of phosphate biofertilizers from bones by phosphate-solubilizing bacteria Bacillus megaterium

“…Many reports of the usefulness of bacteria strain in the plant cultivation can be found in the literature. For example, the reduction of Se(IV) [9], the suppression of S. sclerotiorum on oilseed rape [10], the phytostabilization of Ni contaminated soil [11] and the reduction of septoriatritici blotch [12].…”

Effect of Phosphate Solubilizing Bacteria on the Uptake of Heavy Metals by Corn Plants in a Long-Term Sewage Wastewater Treated Soil

“…Previously, experiments with various plants revealed that the inoculation with Bacillus megatherium SR28C reduced translocation of Ni from roots to shoots compared with the control. This effect was attributed to the increased metal biosorption by Bacillus megatherium SR28C [43].…”