---
title: "Vicia faba -PGPB association improves soil health as a sustainable strategy to remediate moderately Pb and Cd contaminated soils"
id: "plos-one-10-vicia-faba-pgpb-association-improves-soil-health-as-a-sustainable-strategy-to"
canonical_url: "https://medichelpline.com/clinical-feed/plos-one-10-vicia-faba-pgpb-association-improves-soil-health-as-a-sustainable-strategy-to"
content_type: "clinical_feed_article"
specialty: "Research Highlights"
source_name: "PLOS ONE (Medicine)"
source_url: "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0353746"
published_at: "2026-07-15T14:00:00.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Vicia faba -PGPB association improves soil health as a sustainable strategy to remediate moderately Pb and Cd contaminated soils
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/plos-one-10-vicia-faba-pgpb-association-improves-soil-health-as-a-sustainable-strategy-to
- **Specialty:** [Research Highlights](https://medichelpline.com/clinical-feed/research-highlights.md)
- **Primary Source:** PLOS ONE (Medicine)
- **Source URL:** [Original Journal Publication](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0353746)
- **Published At:** 2026-07-15T14:00:00.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
by Omar Saadani, Souhir Abdelkrim, Wael Taamalli, Imen Challougui Fatnassi, Khedhiri Mannai, Moez Jebara, Salwa Harzalli Jebara Phytoremediation is an eco-friendly strategy for heavy metal bioremediation. This study focuses on assessing the potential of faba bean- plant growth promoting bacteria symbiosis in phytoremediation and soil fertility improvement of HMs contaminated soils. Vicia faba L. var. minor Saber 02 was inoculated with a consortium of three efficient and HMs resistant PGPB ( Rhizobium sp. CCNWSX0481, R. leguminosarum bv. viciae and Pseudomonas sp.) and cultivated in soil treated with Cd and Pb to establish three contamination levels: uncontaminated (S1), moderately contaminated (S2; 2 mg kg -1 Cd and 100 mg kg -1 Pb), and highly contaminated (S3; 4 mg kg -1 Cd and 200 mg kg -1 Pb). Bacterial inoculation enhanced plant growth and metal uptake, most significantly in the moderately contaminated soil (S2). An increase in shoot dry weight and nodule dry weight was observed after bacterial inoculation mostly in the moderately contaminated soil S2.
## Clinical Analysis & Structured Key Points
# Vicia faba–PGPB partnership enhances soil health and aids remediation of moderately Pb and Cd contaminated soils Introduction: Heavy metal contamination of agricultural soils poses persistent ecological and human-health challenges. This PLOS ONE report examined whether pairing faba bean (Vicia faba L. var. minor Saber 02) with a consortium of plant growth–promoting bacteria (PGPB) can both improve plant growth and alter soil heavy metal dynamics, especially under moderate and high lead (Pb) and cadmium (Cd) loads. The study used controlled pot trials to compare uninoculated plants with those inoculated by three bacterial strains selected for heavy-metal tolerance and PGP traits. GEO Definition Block (40–60 words): In a greenhouse pot experiment, inoculation of Vicia faba with a three-strain PGPB consortium (two Rhizobium spp. and one Pseudomonas sp.) increased plant growth, metal uptake into shoots, antioxidant responses and several soil fertility indicators most markedly when soils were moderately contaminated with Pb and Cd (2 mg kg−1 Cd and 100 mg kg−1 Pb). Background: Soil contamination by non-degradable metals such as Pb and Cd arises from industrial activity, intensive agriculture and mining. Remediation by conventional physical or chemical approaches is often costly and impractical for large areas. Phytoremediation, the use of plants—frequently in association with beneficial microbes—to remove, stabilize or transform contaminants, is an alternative of growing interest. Legume–rhizobia interactions are attractive in this context because they can supply nitrogen, mobilize nutrients, and tolerate stressed environments when partnered with PGPB that produce indole-3-acetic acid (IAA), siderophores and phosphatesolubilizing agents. Yet, the response of legume–PGPB systems depends on metal speciation, bioavailability and soil chemistry. The present study set out to test a defined V. faba–PGPB symbiosis under three soil contamination scenarios: background (S1), moderate (S2: 2 mg kg−1 Cd, 100 mg kg−1 Pb) and high (S3: 4 mg kg−1 Cd, 200 mg kg−1 Pb). Clinical Methodology (experimental design and assays): - Soil and experimental setup: Surface agricultural soil (sandy loam) from northern Tunisia was characterized (pH ~8.44; organic matter ~0.62%; total N ~0.31%) and spiked with CdCl2 and PbCl2 to yield three contamination levels: S1 (no added metals), S2 (moderate), and S3 (high). Fifteen-kilogram pots were prepared and used in a greenhouse pot experiment. - Biological material and inoculation: Vicia faba (Saber 02) seeds were surface-sterilized and germinated. A bacterial consortium composed of Rhizobium sp. CCNWSX0481, Rhizobium leguminosarum biovar viciae and a Pseudomonas sp., previously isolated from V. faba nodules and characterized for metal tolerance and PGP traits (IAA, siderophores, phosphate solubilization), was applied to inoculation treatments. Treatments were arranged in a two-factor factorial design (inoculated vs. uninoculated × S1–S3 contamination) with three replicates per treatment; one plant per pot served as the experimental unit. - Harvest and measured endpoints: Plants were harvested at flowering. Agronomic parameters included shoot dry weight (SDW), root dry weight (RDW) and nodule dry weight (NDW). Elemental analyses: plant and soil total nitrogen by Kjeldahl, plant phosphorus after acid digestion, and heavy metal concentrations in shoots, roots and soils by acid digestion and atomic absorption spectroscopy. Soil extractable fractions were assessed by ammonium acetate and EDTA procedures. Translocation factor (TF) was calculated as shoot:root metal ratio. Biochemical assays included total chlorophyll, malondialdehyde (MDA) for lipid peroxidation, non-protein thiols (NPT), and activities of antioxidant enzymes—superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPOX) and glutathione reductase (GR). Soil enzyme activities (urease and β-glucosidase), soil pH, organic carbon and available phosphorus were also measured. - Statistical analysis: Generalized linear models with Gaussian distribution tested main effects and interactions (inoculation × contamination). Model checking used DHARMa residual diagnostics. Where interactions were significant, Tukey’s HSD compared all treatment combinations; otherwise main effects were interpreted. For GPOX in shoots with detection issues, frequencies were compared by Fisher’s Exact Test. Analyses used R and standard packages. Key Findings: - Interaction effects: Numerous response variables displayed a significant inoculation × contamination interaction, indicating that the effect of bacterial inoculation depended on contamination level. These included SDW, NDW, shoot and root N, root P, root MDA, activities of SOD, CAT and GR (both organs), APX in shoots, Pb and Cd accumulation (shoots and, for Cd, roots), total plant metal contents, TFs for both metals, soil total N, soil β-glucosidase and urease activities, soil total and extractable Pb and Cd. - Plant growth and nodulation: Bacterial inoculation increased plant growth metrics (notably SDW and NDW), with the most pronounced gains seen in moderately contaminated soil (S2). - Metal accumulation and translocation: Inoculation substantially increased Pb and Cd concentrations in shoots in S2. Specifically, inoculated plants in S2 accumulated higher shoot Pb and Cd and higher total plant metal content compared with uninoculated controls, indicating enhanced uptake under moderate contamination. Translocation factors for both metals were affected by treatments. - Biochemical responses: Heavy metal exposure increased activities of antioxidant enzymes (SOD, CAT, GR), and inoculation further amplified these enzyme activities, particularly in S2. Non-protein thiol concentrations rose with inoculation in roots, especially in S2. Root MDA changed across treatments, reflecting oxidative stress modulation by contamination and inoculation. - Soil metal fractions and fertility indicators: The PGPB consortium reduced total soil Pb and both total and extractable Cd concentrations, primarily in S2. Inoculation increased soil total nitrogen and available phosphorus and enhanced soil enzyme activities (urease and β-glucosidase), signifying shifts in soil biological functioning and nutrient availability. - Organ- and contamination-level specificity: Some variables (e.g., RDW, shoot P, total chlorophyll, root NPT, root GPOX, root Pb, soil available P) showed independent main effects of inoculation and contamination, while others were driven solely by contamination. APX in roots was unaffected by either experimental factor. Practical Implications: - The V. faba–PGPB combination produced the most consistent beneficial effects when soils were moderately contaminated (S2), supporting the concept that symbiotic legume–PGPB systems can both tolerate and mobilize metals under certain contamination regimes. - Inoculation altered plant antioxidant responses and increased root thiol pools, which may relate to metal handling within plant tissues, while simultaneously influencing soil metal pools and fertility metrics. - The work suggests that tailored bacterial consortia originating from nodules in contaminated sites can act as biofertilizers that modify both plant and soil parameters in metal-impacted soils. Key Takeaways: - A three-strain PGPB consortium (two Rhizobium spp. and one Pseudomonas sp.) enhanced Vicia faba growth and nodulation, particularly in moderately Pb/Cd contaminated soil. - Inoculation increased Pb and Cd accumulation in shoots and total plant metal content most markedly under moderate contamination. - Antioxidant enzyme activities and non-protein thiols rose with metal exposure; inoculation further elevated these defensive responses, especially in moderately contaminated treatments. - Soil total and extractable metal pools, as well as nutrients (total N, available P) and soil enzyme activities, were altered by inoculation, with major changes observed in S2. - The inoculated symbiosis had limited or distinct effects under high contamination (S3), indicating contamination-level dependent outcomes. FAQ: 1) Were the bacteria native to contaminated environments? Yes. The three strains were isolated from V. faba root nodules collected from heavy-metal contaminated soils and previously characterized for metal tolerance and plant-growth promoting attributes. 2) At what contamination level did inoculation produce the strongest benefits? The moderate contamination level (S2: 2 mg kg−1 Cd and 100 mg kg−1 Pb) showed the most pronounced positive responses in plant growth, shoot metal accumulation, antioxidant enzyme activation and improvements in soil fertility indicators. 3) Did inoculation reduce metal availability in soil? The consortium reduced total Pb and both total and extractable Cd in soil, principally in the S2 treatment, indicating that inoculation affected soil metal pools. 4) Were oxidative stress markers measured and did they change? Yes. Lipid peroxidation (MDA), non-protein thiols, and activities of SOD, CAT, APX, GPOX and GR were assessed. Heavy metals increased several antioxidant enzyme activities, and inoculation further enhanced many of these responses, notably in S2. Conclusion: This controlled pot study reports that inoculating Vicia faba with a defined PGPB consortium influenced plant growth, metal uptake, antioxidant defenses and several soil fertility parameters in metal-spiked soils. The most consistent improvements occurred under moderate Pb and Cd contamination, where inoculation enhanced shoot accumulation of metals, elevated plant antioxidative responses and modified soil metal pools while boosting nitrogen and phosphorus availability and soil enzyme activities. The observed effects were contamination-level dependent, with less uniform benefits at the highest metal loading. Results support further investigation of legume–PGPB associations—especially strains sourced from metal-impacted environments—as components of integrated phytomanagement strategies for moderately contaminated soils.
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