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Microbes have shown potential for the bioremediation of tannery waste polluted soil. During our previous study, it was observed that heavy metal resistant Burkholderia cepacia CS8 augmented growth and phytoremediation capability of an ornamental plant. Objective of the present research work was to evaluate the capability of B. cepacia CS8 assisted Calendula officinalis plants for the phytoremediation of tannery solid waste (TSW) polluted soil. The TSW treatment significantly reduced growth attributes and photosynthetic pigments in C. officinalis. However, supplementation of B. cepacia CS8 which exhibited substantial tolerance to the TSW amended soil, augmented growth traits, carotenoid, proline, and antioxidant enzymes level in C. officinalis under toxic and nontoxic regimes. Inoculation of B. cepacia CS8 augmented plant growth (shoot length 13%, root length 11%), physiological attributes (chlorophyll a 14%, chlorophyll b 17%), antioxidant enzyme activities (peroxidase 24%, superoxide dismutase 31% and catalase 19%), improved proline 36%, phenol 32%, flavonoids 14% and declined malondialdehyde (MDA) content 15% and hydrogen peroxide (H2O2) level 12% in C. officinalis at TSW10 stress compared with relevant un-inoculated plants of TSW10 treatment. Moreover, B. cepacia CS8 application enhanced labile metals in soil and subsequent metal uptake, such as Cr 19%, Cd 22%, Ni 35%, Fe 18%, Cu 21%, Pb 34%, and Zn 30%, respectively in C. officinalis plants subjected to TSW10 stress than that of analogous un-inoculated treatment. Higher plant stress tolerance and improved phytoremediation potential through microbial inoculation will assist in the retrieval of agricultural land in addition to the renewal of native vegetation. During the current study, it was observed that combination of Calendula officinalis and metal tolerant Burkholderia cepacia CS8 not only improved plant growth but also helped phyto-extraction of pollutants present in the tannery solid waste polluted soil. According to our information, research work describing the phytoremediation potential of native metal tolerant microbes and ornamental plants has not been reported in Pakistan. [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]