Tecnológico Nacional de México/Instituto Tecnológico de Boca del Río, Laboratorio de Investigación en Recursos Acuáticos LIRA, Kilómetro 12, Carretera Veracruz-Córdoba, Boca del Río 94290, Veracruz, Mexico.
Departamento de Microbiología Ambiental y Biotecnología DEMAB, Universidad Autónoma de Campeche, Colonia Buenavista, San Francisco de Campeche 24039, Campeche, Mexico.
Int J Environ Res Public Health. 2018 Feb 11;15(2):314. doi: 10.3390/ijerph15020314.
Cadmium is a major heavy metal found in polluted aquatic environments, mainly derived from industrial production processes. We evaluated the biosorption of solubilized Cd using the extracellular polymeric substances (EPS) produced by sp. MC3B-22 and sp. MC3B-10 (Microbactan); these bacteria were originally isolated from intertidal biofilms off the coast of Campeche, Mexico. EPS were incubated with different concentrations of cadmium in ultrapure water. Residual Cd concentrations were determined by Inductive Coupled Plasma-Optic Emission Spectrometry and the maximum sorption capacity (Qmax) was calculated according to the Langmuir model. EPS were characterized by X-ray photoelectron spectroscopy (XPS) before and after sorption. The Qmax of Cd was 97 mg g for Microbactan and 141 mg g for MC3B-22 EPS, these adsorption levels being significantly higher than previously reported for other microbial EPS. In addition, XPS analysis revealed changes in structure of EPS after biosorption and showed that amino functional groups contributed to the binding of Cd, unlike other studies that show the carbohydrate fraction is responsible for this activity. This work expands the current view of bacterial species capable of synthesizing EPS with biosorbent potential for cadmium and provides evidence that different chemical moieties, other than carbohydrates, participate in this process.
镉是一种主要的重金属，存在于受污染的水生环境中，主要来源于工业生产过程。我们评估了 sp. MC3B-22 和 sp. MC3B-10（微杆菌）产生的胞外聚合物（EPS）对可溶性 Cd 的吸附作用；这些细菌最初是从墨西哥坎佩切海岸的潮间带生物膜中分离出来的。将 EPS 在超纯水中与不同浓度的镉一起孵育。通过电感耦合等离子体质谱法（ICP-OES）测定残留 Cd 浓度，并根据朗缪尔模型计算最大吸附容量（Qmax）。在吸附前后用 X 射线光电子能谱（XPS）对 EPS 进行了表征。Cd 的 Qmax 为 Microbactan 的 97 mg g 和 MC3B-22 EPS 的 141 mg g，这些吸附水平明显高于以前报道的其他微生物 EPS。此外，XPS 分析表明，生物吸附后 EPS 的结构发生了变化，表明氨基官能团有助于 Cd 的结合，而其他研究表明，碳水化合物部分负责这种活性。这项工作扩展了目前对具有合成 EPS 能力的细菌物种的认识，这些 EPS 具有对镉的生物吸附潜力，并提供了证据表明，除了碳水化合物之外，还有其他化学部分参与了这个过程。
