Department of Microbiology, Faculty of Science, University of Mazandaran, Babolsar, Iran.
Department of Marine and Environmental, Faculty of Marine and Oceanic Sciences, University of Mazandaran, Babolsar, Iran.
Sci Rep. 2024 Aug 19;14(1):19168. doi: 10.1038/s41598-024-70402-w.
Toxic and heavy metals cause direct and indirect damage to the environment and ultimately to humans. This study involved the isolation of indigenous bacteria from heavy metal-contaminated environments that have the ability to bioabsorb heavy metals such as cadmium, nickel, and lead. The bioabsorption process was optimized by varying parameters such as temperature, metal concentration, number of bacteria, pH, and more. The bacterial isolates were investigated in terms of morphology, biochemistry, and phylogeny, with 12 strains chosen in the initial stage and one strain chosen in the final stage. It should be remembered that the metal uptake capacity of all isolates was approximately calculated. A box and reactor were designed to house these optimized microorganisms. Based on biochemical, morphological, and molecular results, the isolated strain was found to be closely related to the Bacillus genus. In the first five steps of testing, the ideal pH for removing lead alone, lead with cadmium, lead with nickel, and lead ternary (with cadmium and nickel) by Bacillus bacteria was found to be 7, 6, 5.5, and 6.5, respectively. The absorption efficiencies for single lead (unary), lead together with nickel, cadmium (binary), and ternary (lead with cadmium and nickel) were found to be 0.36, 0.25, 0.22, and 0.21 mmol/g, respectively. The ideal temperature for lead removal was around 30 °C. The adsorption isotherm for each lead metal in different states was found to be similar to the Langmuir isotherm, indicating that the surface absorption process is a single-layer process. The kinetics of the process follow the second-order kinetic model. The amount of Bacillus bacteria biomass obtained during this process was approximately 1.5 g per liter.
有毒重金属直接或间接对环境造成损害，最终也会危害人类健康。本研究从重金属污染环境中分离出具有生物吸附重金属（如镉、镍和铅）能力的土著细菌。通过改变温度、金属浓度、细菌数量、pH 值等参数来优化生物吸附过程。从形态学、生物化学和系统发育学等方面对细菌分离株进行了研究，在初始阶段选择了 12 株，在最后阶段选择了 1 株。需要注意的是，所有分离株的金属吸收能力都是大致估算的。设计了一个盒子和一个反应器来容纳这些优化后的微生物。基于生化、形态学和分子结果，分离株被发现与芽孢杆菌属密切相关。在 Bacillus 菌去除单独的铅、铅和镉、铅和镍以及铅三元（与镉和镍）的前五个测试步骤中，发现理想的 pH 值分别为 7、6、5.5 和 6.5。单独的铅（一元）、铅与镍、镉（二元）和三元（铅与镉和镍）的吸收效率分别为 0.36、0.25、0.22 和 0.21 mmol/g。去除铅的理想温度约为 30°C。不同状态下每种铅金属的吸附等温线与朗缪尔等温线相似，表明表面吸附过程是单层过程。该过程的动力学符合二级动力学模型。在此过程中获得的芽孢杆菌细菌生物量约为每升 1.5 克。
