ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Microbiotechnology
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1644466
This article is part of the Research TopicMicrobial Remediation of Heavy Metal PollutionView all articles
Molecular characterization of heavy metal-tolerant bacteria and their potential for bioremediation and plant growth promotion
Provisionally accepted
- 1University of Science and Technology, Bannu, Pakistan
- 2National Agricultural Research Center, Islamabad, Pakistan
- 3National University of Sciences and Technology, Islamabad, Pakistan
- 4University of Management and Technology, Lahore, Pakistan
- 5Higher Eduction Commission, Islamabad, Pakistan
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Heavy metal pollution adversely affects soil health by disturbing the soil microbial community. The present study was conducted to isolate bacterial strains tolerant to heavy metals (Cr, Cu, Pb, As, Cd) and to investigate their potential use in soil bioremediation and agricultural sustainability. More than 68 strains were isolated from industrial discharge and screened for the maximum tolerance limit (MTL) of heavy metals. It was found that some strains showed a maximum tolerance of up to 3600 mg/L for Cr, 3300 mg/L for Cu, 3000 mg/L for Cd and As, 2100 mg/L for Pb. Phylogenetically different strains (23) were further analyzed for biosorption of heavy metals. Maximum biosorption occurred for Pb, followed by Cd and Cu, whereas the biosorption of As and Cr was significantly lower for all the isolated strains. 16S rRNA gene sequence-based molecular identification of heavy metal-tolerant strains revealed that the isolated strains belonged to 19 genera, and the dominant genera included Bacillus (21%), Pseudomonas (12%) and Staphylococcus (10%). Based on the molecular characterization results for acdS and nifH genes, at least seven strains were identified containing both genes in their genome (15 isolates contained the nifH gene, whereas 8 strains contained the acdS gene). The impacts of four strains (NCCP-650 T , NCCP-614, NCCP-644 and NCCP-602) on Brassica napus growth were evaluated under axenic conditions when treated with 50 mg /L solution of each studied metal. The results showed that the strains increased the growth of B. napus plants in comparison to the control (no addition of strain or metal). Among the strains tested, NCCP-650 T demonstrated the greatest improvement in growth of B. napus plants. These heavymetal(s)-tolerant strains can potentially be used as bioinoculants (biofertilizers) for enhancing agricultural productivity in metal-contaminated soils. The results also indicated that some of these isolates can be used for the bioremediation of soil/water systems contaminated with heavy metals such as Pb, Cd and Cu.
Keywords: heavy metals, PGPR, tannery discharge, Biosorption, bioremediation
Received: 11 Jun 2025; Accepted: 14 Jul 2025.
Copyright: © 2025 Abbas, Zulfiqar, Arshad, Khalid, Hussain and Ahmed. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Iftikhar Ahmed, National Agricultural Research Center, Islamabad, Pakistan
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