Abstract Microbially induced calcium carbonate precipitation (MICP) method can convert heavy metals from mobile forms into more stable crystals. This study was conducted to investigate the removal of cadmium (Cd) by Sporosarcina pasteurii through the urea hydrolysis pathway. Cd removal from solution containing 0.5, 1, and 2 mmol l−1 of Cd (as CdCl2.5H2O) were measured firstly, and then the amount of Cd removal was studied in two sandy and clay soils containing 10, 20, 40, and 50 mg kg−1 of Cd. The experiments were arranged in complete randomized design with three replications. Minimum inhibitory concentration (MIC) of Cd for bacteria growth was attained as 2 mmol l−1, after 48 h of incubation. Cd removal efficacy was 99.6% in 0.5 mmol l−1 and 99.8% in 1 and 2 mmol l−1 Cd solutions. In both soils that were inoculated with bacteria, Cd concentration decreased in solution-exchangeable fraction significantly (p ≤ 0.05). The Cd concentration in the solution-exchangeable fraction of sandy and clay soils were decreased to 85.9, 61.1, 74.3, 80.3% and 89.3, 86.6, 76, 75.6% of its initial values (i.e., 10, 20, 40, and 50 mg kg−1), respectively. The amount of Cd in carbonate fraction in both sandy and clay soil increased significantly in the presence of bacteria (p ≤ 0.05). The results revealed that MICP-based removal of heavy metals via co-precipitation with calcite not only immobilized Cd in studied soils but also improved the microbial and enzymatic activities.

中文翻译：

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培养 1 周后微生物诱导碳酸钙沉淀对沙质和粘土土壤中镉的生物修复

摘要 微生物诱导碳酸钙沉淀（MICP）方法可以将重金属从流动形态转化为更稳定的晶体。本研究旨在研究巴氏孢子菌通过尿素水解途径去除镉 (Cd) 的情况。首先测量了从含有 0.5、1 和 2 mmol l-1 Cd（以 CdCl2.5H2O 计）的溶液中的 Cd 去除量，然后在含有 10、20、40 和50 mg kg−1 Cd。实验以完全随机设计安排，三个重复。培养 48 小时后，Cd 对细菌生长的最小抑制浓度 (MIC) 为 2 mmol l-1。Cd 去除效率在 0.5 mmol l-1 中为 99.6%，在 1 和 2 mmol l-1 Cd 溶液中为 99.8%。在接种了细菌的两种土壤中，溶液可交换部分中的 Cd 浓度显着降低 (p ≤ 0.05)。砂质和黏土的溶液可交换部分中的 Cd 浓度降低到其初始值的 85.9、61.1、74.3、80.3% 和 89.3、86.6、76、75.6%（即 10、20、40 和 50 mg kg-1)，分别。在细菌存在的情况下，沙土和粘土中碳酸盐部分的 Cd 含量显着增加（p ≤ 0.05）。结果表明，基于 MICP 的通过与方解石共沉淀去除重金属不仅固定了研究土壤中的 Cd，而且提高了微生物和酶的活性。分别为其初始值的 6%（即 10、20、40 和 50 mg kg-1）。在细菌存在的情况下，沙土和粘土中碳酸盐部分的 Cd 含量显着增加（p ≤ 0.05）。结果表明，基于 MICP 的通过与方解石共沉淀去除重金属不仅固定了研究土壤中的 Cd，而且提高了微生物和酶的活性。分别为其初始值的 6%（即 10、20、40 和 50 mg kg-1）。在细菌存在的情况下，沙土和粘土中碳酸盐部分的 Cd 含量显着增加（p ≤ 0.05）。结果表明，基于 MICP 的通过与方解石共沉淀去除重金属不仅固定了研究土壤中的 Cd，而且提高了微生物和酶的活性。