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The current research was performed to evaluate the effect ofBacillus megateriumMCR-8 on mitigation of nickel (Ni) stress inVinca roseagrown on Ni-contaminated soil (50, 100, and 200 mg Ni kg−1soil). The treated plants exhibited reduced growth, biomass, gas exchange capacity, and chlorophyll (Chl) content under Ni stress. The inoculated plants growing in Ni-contaminated media exhibited relatively higher growth, total soluble protein, and proline contents. Similarly, bacterial inoculation improved the activity of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) under Ni stress. The Ni stress alleviation in inoculated plants was attributed to the reduced level of malondialdehyde (MDA) and hydrogen peroxide (H2O2), enhanced synthesis of protein, proline, phenols, and flavonides in conjunction with improved activity of antioxidant enzymes. The growth-promoting characteristics of microbe such as 1-aminocyclopropane-1-carboxylate deaminase (ACCD) and phosphate solubilization activity, siderophore, and auxin production capability also improved the growth and stress mitigation in inoculated plants. Furthermore, the inoculated plants exhibited higher value for bioconcentration factor (BCF), translocation factor (TF), and resulted in higher loss of Ni content from soil. The current results exhibited the beneficial role ofB. megateriumMCR-8 regarding stress alleviation and Ni phytoextraction byV. rosea. [ABSTRACT FROM AUTHOR]

During our current study we evaluated the effect of ethylenediaminetetracetic acid (EDTA) and Enterobacter sp. CS2 on nickel stress alleviation and phytoextraction by Impatiens balsamina L in spiked soil. Nickel resistant Enterobacter sp. CS2 was isolated from soil polluted by industrial effluents. The I. balsamina seeds primed with Enterobacter sp. CS2 were raised in EDTA-supplemented soil (10 mM) contaminated with 0, 100, 200, and 300 mg kg-1 Ni for 50 days. The effect of different treatments on plant growth attributes, nickel tolerance index, bioconcentration factor, and translocation factor were evaluated. The Ni stress reduced plant growth, carotenoids, and chlorophyll (chl) content. However, higher Ni uptake and proline contents were observed in plants growing in Ni-contaminated soils. The Enterobacter sp. CS2 inoculation further enhanced Ni uptake and proline contents in I. balsamina plants growing under Ni stress. The inoculated plants showed improved shoot length, root length, carotenoid content, chl 'a' and 'b' contents, root and shoot dry weight. The Ni tolerance index in Enterobacter sp. CS2-assisted plants was much higher compared to un-inoculated ones. The inoculated plants supplemented with EDTA enhanced 39%, 34%, and 30% Ni uptake in roots respectively under 100, 200, and 300 mg kg-1 of Ni treatment as compared with un-inoculated plants. The data regarding bioconcentration factor and translocation factor showed that Ni phytoextraction capability of I. balsamina plants was significantly enhanced with the supplementation of Enterobacter sp. CS2 and EDTA. [ABSTRACT FROM AUTHOR]