Exploring the synergistic effect of chromium (Cr) tolerant Pseudomonas aeruginosa and nano zero valent iron (nZVI) for suppressing Cr uptake in Aloe Vera

Komal; Muhammad Shabaan; Qasim Ali; Hafiz Naeem Asghar; Zahir Ahmad Zahir; Kashmala Yousaf; Noreen Aslam; Usman Zulfiqar; Mukkaram Ejaz; Mona S Alwahibi; M Ajmal Ali

doi:10.1080/15226514.2024.2327838

Exploring the synergistic effect of chromium (Cr) tolerant Pseudomonas aeruginosa and nano zero valent iron (nZVI) for suppressing Cr uptake in Aloe Vera

Int J Phytoremediation. 2024 Mar 15:1-12. doi: 10.1080/15226514.2024.2327838. Online ahead of print.

Authors

Affiliations

¹ Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, Faisalabad, Pakistan.
² Land Resources Research Institute, National Agricultural Research Centre, Islamabad, Pakistan.
³ Department of Soil Sciences, The Islamia University of Bahawalpur, Bahawalpur, Pakistan.
⁴ Institute of Physiology and Pharmacology, University of Agriculture Faisalabad, Faisalabad, Pakistan.
⁵ Department of Agronomy, Faculty of Agriculture and Environment, The Islamia University of Bahawalpur, Bahawalpur, Pakistan.
⁶ Institute of Physics-Centre for Science and Education, Division of Geochronology and Environmental Isotopes, Silesian University of Technology, Gliwice, Poland.
⁷ Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, Saudi Arabia.

PMID: 38488053
DOI: 10.1080/15226514.2024.2327838

Abstract

Chromium (Cr) contamination of soil has substantially deteriorated soil health and has interfered with sustainable agricultural production worldwide and therefore, its remediation is inevitable. Inoculation of plant growth promoting rhizobacteria (PGPR) in association with nanotechnology has exerted broad based impacts in agriculture, and there is an urgent need to exploit their synergism in contaminated soils. Here, we investigated the effect of co-application of Cr-tolerant "Pseudomonas aeruginosa CKQ9" strain and nano zerovalent iron (nZVI) in improving the phytoremediation potential of aloe vera (Aloe barbadensis L.) under Cr contamination. Soil was contaminated by using potassium dichromate (K₂Cr₂O₇) salt and 15 mg kg^-1 contamination level in soil was maintained via spiking and exposure to Cr lasted throughout the duration of the experiment (120 days). We observed that the co-application alleviated the adverse impacts of Cr on aloe vera, and improved various plant attributes such as plant height, root area, number of leaves and gel contents by 51, 137, 67 and 49% respectively as compared to control treatment under Cr contamination. Similarly, significant boost in the activities of various antioxidants including catalase (124%), superoxide dismutase (87%), ascorbate peroxidase (36%), peroxidase (89%) and proline (34%) was pragmatic under contaminated soil conditions. In terms of soil Cr concentration and its plant uptake, co-application of P. aeruginosa and nZVI also reduced available Cr concentration in soil (50%), roots (77%) and leaves (84%), while simultaneously increasing the relative production index by 225% than un-inoculated control. Hence, integrating PGPR with nZVI can be an effective strategy for enhancing the phytoremediation potential of aloe vera.

Keywords: Aloe vera; PGPR; chromium; industrial effluents; nano zerovalent iron; phytoremediation.

Plain language summary

Combined effect of PGPR and nanotechnology in the bioremediation of toxic contaminants is well reported in literature. Most of these reports comprise the use of hyperaccumulator plants for phytoextraction of heavy metals. However, phytostabilization potential of hyperaccumulators is still un-explored. Current study investigated the role of PGPR and Fe-NPs in suppressing the uptake of Cr in aloe vera, a hyperaccumulator plant.