Burkholderia sp. EIKU24-derived selenium nanoparticles: Characterization, multifunctional bioactivities and their role in sustainable rice cultivation against arsenic stress

Abstract

The current study employed a rice root plaque-associated bacterium, Burkholderia sp. EIKU24, with the competency to synthesize spherical and crystalline biogenic selenium nanoparticles (BioSeNPs) that have size variability between 230 and 330 nm, as confirmed by SEM and TEM analysis. FT-IR and electron microscopy further revealed a biomolecular coating around the NPs that might have contributed significantly to their antibacterial activity against potential pathogenic Gram-positive and Gram-negative bacteria. The BioSeNPs suspension (10 mg mL⁻¹) inhibited 78 % and 67 % of Staphylococcus aureus and Pseudomonas aeruginosa biofilms, respectively. Furthermore, BioSeNPs showed very high antioxidant capability, reflected by 90 % relative DPPH scavenging activity and photocatalytic capability by the degradation of 86 % methylene blue (10 mg L⁻¹) solution within a contact time of 30 min. Compared to hydro or Na₂SeO₃ priming, rice seeds from BioSeNPs-priming outperformed in all tested seed germination parameters. Hydroponic cultivation showed better health and growth of the rice plants by an increase in root and shoot lengths, wet and dry biomass, and chlorophyll content, both in arsenic (As)-exposed and unexposed seedlings emerging from BioSeNPs-primed seeds. Notably, in such seedlings, exposure to As did not alter the growth much, indicating increased resilience to As through BioSeNPs priming. Besides, the priming of BioSeNPs decreased the translocation of As to shoot and root by about 50 % compared with hydro priming. The bioactivities, dye degradation, and growth promotion coupled with As resilience in rice seedlings consolidate the sustainable agricultural potential of BioSeNPs. However, their impact on soil ecology and interaction with other contaminants requires further study.