Siderophore-producing endophytic bacteria from Bougainvillea promote lead phytostabilization in Trigonella foenum-graecum.

Abstract

Heavy metal pollution poses serious risks to agriculture and ecosystems, particularly in developing regions. Lead (Pb) contamination is persistent, non-biodegradable, and can enter the food chain via plant uptake, posing significant human health concerns. Phytoremediation offers a cost-effective and eco-friendly solution; however, its efficiency is often constrained by reduced plant growth under metal stress and limited metal bioavailability. This study explores phytostabilization using siderophore-producing endophytic bacteria isolated from Bougainvillea spp. leaves collected from Laiyala, Gujarat, India. The isolates were morphologically and biochemically characterized and screened for siderophore production using the Chrome Azurol S (CAS) assay. A potent strain-BH5 was evaluated in association with Trigonella foenum-graecum (fenugreek) under Pb-contaminated conditions. Inoculated plants exhibited enhanced growth, increased biomass, and improved Pb stabilization compared to uninoculated controls. Lead accumulation was quantified using atomic absorption spectroscopy (AAS), indicating siderophore-mediated enhancement of metal bioavailability. Molecular identification was performed through 16S rRNA gene sequencing, and structural characterization of siderophores is ongoing using NMR and HRMS. Statistical analysis (ANOVA) revealed significant treatment effects, with BH5 showing superior performance. These findings highlight the potential of siderophore-producing endophytes to enhance Pb phytostabilization and improve plant tolerance under metal stress.