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<p>Heavy metals, such as cadmium (Cd), in mining-impacted soils pose serious environmental and health risks, necessitating the development of effective bioremediation strategies. Using plate streaking methods, this study isolated a novel <i>Bacillus cereus</i> strain, designated SP1, from acidic, heavy metal-contaminated soil in Lujiang County, Anhui Province, China. The strain was identified through Gram staining, biochemical tests, and 16&#xa0;S rRNA sequencing. Scanning electron microscopy (SEM) was used to assess the strain’s morphological characteristics, and various parameters were analyzed to determine its biosorption potential. <i>B. cereus</i> SP1 exhibited high Cd tolerance, growing at concentrations up to 200&#xa0;mg/L, with optimal growth conditions at 30&#xa0;°C, pH 7, and 1% NaCl. The highest Cd removal efficiency was observed under these conditions with an inoculation of 4%. To understand how SP1 adsorbs Cd, we tested mathematical models describing surface interactions. The data best fit a multilayer adsorption model (Freundlich isotherm), indicating Cd binds to SP1’s surface in multiple layers rather than a single sheet. Kinetic analysis revealed that Cd uptake follows chemisorption—a process driven by strong chemical bonds between Cd and bacterial cell components. In response to Cd exposure, <i>B. cereus</i> SP1 exhibited a dose- and time-dependent increase in metallothioneins, phytochelatins, and antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Additionally, extracellular polymer production was enhanced, contributing to its ability to detoxify cadmium. Considering its high tolerance, efficient Cd removal, and detoxification capabilities, <i>B. cereus</i> SP1 presents a promising candidate for bioremediation of Cd-contaminated environments. Future research will investigate its interactions with plant roots and other microorganisms to develop integrated phytoremediation strategies.</p> Graphical Abstract <p></p>

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Cadmium Bioaccumulation by Novel Bacillus Cereus SP1 Isolated from Mining-Impacted Soil: Adsorption Isotherms and Detoxification Mechanisms

  • 期刊论文

  • 发表日期：

    2025年9月2日

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  • Sehar Razzaq,
  • Beibei Zhou,
  • Ruonan Jia,
  • Hongchao Guo

摘要

Heavy metals, such as cadmium (Cd), in mining-impacted soils pose serious environmental and health risks, necessitating the development of effective bioremediation strategies. Using plate streaking methods, this study isolated a novel Bacillus cereus strain, designated SP1, from acidic, heavy metal-contaminated soil in Lujiang County, Anhui Province, China. The strain was identified through Gram staining, biochemical tests, and 16 S rRNA sequencing. Scanning electron microscopy (SEM) was used to assess the strain’s morphological characteristics, and various parameters were analyzed to determine its biosorption potential. B. cereus SP1 exhibited high Cd tolerance, growing at concentrations up to 200 mg/L, with optimal growth conditions at 30 °C, pH 7, and 1% NaCl. The highest Cd removal efficiency was observed under these conditions with an inoculation of 4%. To understand how SP1 adsorbs Cd, we tested mathematical models describing surface interactions. The data best fit a multilayer adsorption model (Freundlich isotherm), indicating Cd binds to SP1’s surface in multiple layers rather than a single sheet. Kinetic analysis revealed that Cd uptake follows chemisorption—a process driven by strong chemical bonds between Cd and bacterial cell components. In response to Cd exposure, B. cereus SP1 exhibited a dose- and time-dependent increase in metallothioneins, phytochelatins, and antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Additionally, extracellular polymer production was enhanced, contributing to its ability to detoxify cadmium. Considering its high tolerance, efficient Cd removal, and detoxification capabilities, B. cereus SP1 presents a promising candidate for bioremediation of Cd-contaminated environments. Future research will investigate its interactions with plant roots and other microorganisms to develop integrated phytoremediation strategies.

Graphical Abstract