Agromyces sp. CS16去除水体中重金属镉、镍、铜、锌离子的研究

Removal of cadmium, nickel, copper, and zinc ions from water by Agromyces sp. CS16

摘要:

【目的】本研究从深圳福田红树林表层土壤中分离出一株潜在放线菌新种Agromyces sp. CS16，研究其对水体中重金属的去除能力以及特征，并初步探究其在去除水体重金属中的实际应用，为利用微生物修复水体重金属污染提供技术支持。【方法】测定菌株CS16对Cd²⁺、Ni²⁺、Cu²⁺、Zn²⁺的去除能力；测定CS16对Cd²⁺、Ni²⁺、Cu²⁺、Zn²⁺在胞外吸附和胞内吸收的占比；通过全基因组测序分析CS16基因组中与重金属耐受相关的基因；采用海藻酸钠和聚乙烯醇将CS16包埋，并测定包埋后CS16对重金属的去除能力。【结果】放线菌Agromyces sp. CS16在Cd²⁺浓度为10 μg/mL时对其的去除量最大，为32.95 mg/g，此时对溶液中Cd²⁺的去除率也最高，达到83.71%；菌株CS16在Ni²⁺浓度为75 μg/mL时去除量最大，为25.09 mg/g，在Ni²⁺浓度为25 μg/mL时去除率最高，为70.27%；CS16在Cu²⁺浓度为150 μg/mL时去除量最大，为30.69 mg/g，在Cu²⁺浓度为30 μg/mL时去除率最高，为80.11%；CS16在Zn²⁺浓度为125 μg/mL时去除量最大，为39.29 mg/g，在Zn²⁺浓度为25 μg/mL时去除率最高，为88.91%。菌株CS16全基因组预测总共有3 744个基因，其中有37个基因推测与Cd²⁺、Ni²⁺、Cu²⁺、Zn²⁺的抗性相关。CS16主要通过将重金属吸附在细胞外表面来去除水体中的重金属，在被海藻酸钠(sodium alginate, SA)与聚乙烯醇(polyvinyl alcohol, PVA)材料包埋后，CS16对Cd²⁺的去除能力下降，但对Ni²⁺、Cu²⁺、Zn²⁺的去除能力显著提高。【结论】放线菌Agromyces sp. CS16是一株分离自红树林表层沉积物的新菌，本研究测定了CS16对Cd²⁺、Ni²⁺、Cu²⁺、Zn²⁺的去除能力，从细胞层面和基因层面初步探索了其对Cd²⁺、Ni²⁺、Cu²⁺、Zn²⁺的去除机理，并成功用海藻酸钠和聚乙烯醇将其包埋，为探究微生物去除水体重金属离子的机制和之后应用CS16修复水体重金属污染提供了理论基础。

Abstract:

[Objective] A potential new actinomycete strain Agromyces sp. CS16 was isolated from the surface soil of the mangrove in Futian, Shenzhen. We studied the capacity and application of the strain in the removal of heavy metals from water, aiming to provide technical support for the bioremediation of heavy metal-polluted water. [Methods] The capacity of strain CS16 in removing Cd²⁺, Ni²⁺, Cu²⁺, and Zn²⁺, and the extracellular and intracellular removal rates of the metal ions were determined. Moreover, the whole genome sequencing was performed to identify the genes associated with the heavy metal tolerance in strain CS16. Furthermore, CS16 was embedded with sodium alginate and polyvinyl alcohol, and the capacities of CS16 to remove heavy metals after embedding were also determined.[Results] Agromyces sp. CS16 presented great metal removal capacity. For Cd²⁺, the strain showed the maximum removal capacity of 32.95 mg/g and the maximum removal rate of 83.71% with the initial Cd²⁺ concentration of 10 μg/mL. For Ni²⁺, Agromyces sp. CS16 presented the maximum removal capacity of 25.09 mg/g with the initial Ni²⁺ concentration of 75 μg/mL, and it presented the maximum removal rate of 70.27% with the initial Ni²⁺ concentration of 10 μg/mL. For Cu²⁺, CS16 had the maximum removal capacity of 30.69 mg/g with the initial Cu²⁺ concentration of 150 μg/mL and the maximun removal rate of 80.11% with the initial Cu²⁺ concentration of 30 μg/mL. For Zn²⁺, the strain had the maximum removal capacity of 39.29 mg/g with the initial Zn²⁺ concentration of 125 μg/mL and the maximun removal rate of 88.91% with the initial Zn²⁺ concentration of 25 μg/mL. A total of 3 744 genes were predicted in the whole genome of strain CS16, of which 37 genes were deduced to be associated with the resistance to Cd²⁺, Ni²⁺, Cu²⁺, and Zn²⁺. CS16 mainly removed heavy metals in water by adsorbing heavy metal ions on cell walls. The embedding with sodium alginate (SA) and polyvinyl alcohol (PVA) decreased the removal capacity of CS16 for Cd²⁺ and improved the removal capacities for Ni²⁺, Cu²⁺, and Zn²⁺. [Conclusion] Agromyces sp. CS16 is a new strain isolated from mangrove surface sediments, with great capacity in removing Cd²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ from water. We explored the metal removal mechanisms of the strain at both cellular and genetic levels. CS16 was embedded with sodium alginate and polyvinyl alcohol and the embedding product presented better removal capacity for Ni²⁺, Cu²⁺, and Zn²⁺. In summary, CS16 is an efficient microbial agent in bioremediation of heavy metal-polluted water. Moreover, the findings of this study provide a theoretical basis for deciphering the mechanism of removing heavy metal ions from water by microorganisms.