Bioremediation of Lead and Cadmium from Liquid Media by Metal-Tolerant Bacillus cereus MS54 and Bacillus amyloliquefaciens NO10

Document Type : Original Article

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Biology Department, College of Science, Jazan University, Jazan, KSA

Abstract

This study aimed to evaluate the bioremediation potential of two highly metal-tolerant bacterial isolates, SS1 and SS2, identified as Bacillus cereus MS54 and Bacillus amyloliquefaciens NO10, respectively, for the removal of lead (Pb²⁺) and cadmium (Cd²⁺) from contaminated environments. The isolates were identified using 16S rRNA gene sequencing and selected for their high resilience under heavy metal-contaminated conditions. Their ability to adsorb Pb²⁺ and Cd²⁺ ions from nutrient broth medium was assessed at varying concentrations (Pb²⁺: 500, 2000, 6000 µg·ml⁻¹; Cd²⁺: 25, 250, 500 µg·ml⁻¹) over different time intervals (24, 72, and 120 hours).
Bacillus cereus MS54 demonstrated high Pb²⁺ removal efficiency, achieving 35.43% removal at 24 hours and increasing to 98.65% after 120 hours at the lowest concentration (500 µg·ml⁻¹). At higher concentrations (2000 and 6000 µg·ml⁻¹), Pb²⁺ uptake continued but showed a slight reduction in efficiency, likely due to saturation effects. Conversely, Bacillus amyloliquefaciens NO10 exhibited strong Cd²⁺ removal, achieving 38.94% removal at 24 hours and reaching 96.90% at 120 hours at the lowest concentration (25 µg·ml⁻¹). Higher concentrations (250 and 500 µg·ml⁻¹) consistently increased metal uptake.
These findings highlight that both bacterial strains effectively removed their respective metals, with B. cereus MS54 excelling in Pb²⁺ and B. amyloliquefaciens NO10 in Cd²⁺ remediation. The mechanisms of metal uptake involve passive biosorption, active transport, biosurfactant production, and intracellular sequestration. This study demonstrates the potential of these strains as bioremediation agents for heavy metal contamination in both aqueous and soil environments.

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