首页|Lead (Pb~(2+)) biosorption and bioaccumulation efficiency of Enterobacter chuandaensis DGI-2: Isotherm, kinetics and mechanistic study for bioremediation
Lead (Pb~(2+)) biosorption and bioaccumulation efficiency of Enterobacter chuandaensis DGI-2: Isotherm, kinetics and mechanistic study for bioremediation
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Heavy metal (HM) contamination, particularly lead (Pb~(2+)), threatens environmental and agricultural sustainability,necessitating effective remediation strategies. This study evaluates the Pb~(2+) sequestration potential ofEnterobacter chuandaensis DGI-2, an HM-tolerant rhizobacterium isolated from a Pb-contaminated rhizosphere.DGI-2 exhibited high Pb~(2+) removal efficiency, achieving 94.73 % removal at 100 μg/mL and 69.09 % at 750 μg/mL over 96 h, primarily through cell surface and exopolysaccharide (EPS) adsorption. Biosorption studiesdemonstrated higher Pb~(2+) uptake in living biomass (102.95 mg/g, 68.63 %) than in dead biomass (98.61 mg/g,65.74 %) under controlled conditions (0.5 g/L biomass, pH-6.5, 720 min). Mechanistic analyses revealed thatPb~(2+) adsorption primarily involved interactions with –OH, –COOH, and –PO_4~(3-) functional groups, facilitated bymultilayer sorption, complexation, and ion exchange. Moreover, a 210.66 % increase in phosphatase activitypromoted Pb~(2+) precipitation, forming stable Pb-phosphate minerals (e.g., Pb₅(PO_4)_3Cl, Pb_(10)(PO_4)_6(OH)_2), asconfirmed by X-ray diffraction (XRD), significantly contributing to Pb sequestration. Regeneration studiesdemonstrated the biomass’ reusability over four cycles. Soil microcosm experiments showed an 11.7–13.1 %reduction in bioavailable Pb, with greater stabilization in non-sterile soils, suggesting synergistic effects withnative microbiota. Additionally, DGI-2 exhibited plant growth-promoting (PGP) traits, reducing phytotoxicity, enhancing soil health and phytostabilization potential, positioning it as a sustainable biosorbent for Pb~(2+) remediation.
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