Endophytic Pantoea agglomerans enhances lead phytoremediation and stress resilience of Calotropis procera in hydroponic system

Heavy metal contamination with lead poses a critical threat to agricultural productivity and environmental sustainability due to its toxicity, persistence, and bioaccumulative nature. Conventional remediation methods are often expensive and can generate secondary pollution, prompting increased interest in phytoremediation as an eco-friendly alternative. This study investigates the potential of Pantoea agglomerans, an endophytic bacterium isolated from Prosopis juliflora seeds, to enhance the phytoremediation capabilities of Calotropis procera- a plant known for its tolerance and accumulation of heavy metals- grown hydroponically under varying lead concentrations (0–80 mg/L). X-ray fluorescence analysis indicated altered lead distribution and nutrient profiles in C. procera, suggesting possible lead immobilization or detoxification. Hydroponic experiments demonstrated that inoculated plants exhibited improved growth parameters (shoot and root dry weight, leaf dimensions) and higher chlorophyll and carotenoid contents compared to non-inoculated controls. Lead-induced oxidative damage was mitigated in Pantoea-treated plants, as evidenced by lower hydrogen peroxide and malondialdehyde levels, along with elevated activities of antioxidant enzymes (catalase and guaiacol peroxidase). Enhanced proline and protein contents further indicated improved stress tolerance and metabolic stability. This study highlights endophyte-assisted phytoremediation as a cost-effective, sustainable solution for lead-contaminated environments, with potential applications in large-scale remediation efforts.