Binding of heavy metal ions in aggregates of microbial cells, EPS and biogenic iron minerals measured in-situ using metal- and glycoconjugates-specific fluorophores
Binding of heavy metal ions in aggregates of microbial cells, EPS and biogenic iron minerals measured in-situ using metal- and glycoconjugates-specific fluorophores
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使用金属和糖复合物特异性荧光团原位测量微生物细胞、EPS 和生物铁矿物质聚集体中重金属离子的结合
DOI：
10.1016/j.gca.2016.02.016
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发表时间：
2016-05-01
影响因子：
5
通讯作者：
Obst，Martin
中科院分区：
文献类型：
--
作者：
Hao，Likai;Guo，Yuan;Obst，Martin
由细菌细胞、胞外聚合物 (EPS) 和 Fe(II) 氧化细菌形成的 Fe(III) 矿物质组成的聚集体在发生 Fe 循环的本体或微观化学界面中很常见。细胞、EPS和矿物质的高吸附能力和结合能力控制着重金属的移动性和归宿。然而，目前尚不清楚金属将与这些组分中的哪一种结合成复杂的聚集体。为了澄清这个问题，本研究重点使用共焦激光扫描显微镜 (CLSM) 结合金属和纳米粒子，对吸附在细胞上的重金属、构成 EPS 大部分成分的糖复合物以及由光养型 Fe(II) 氧化细菌氧化亚铁红杆菌 SW2 形成的 Fe(III) 矿物聚集体进行 3D 绘图。 糖缀合物特异性荧光团。本研究评估了糖复合物、微生物细胞表面和（生物）Fe(III) 矿物质的影响，以及二价铁和三价铁对重金属吸附的有效性。这项研究的分析提供了亚微米尺度聚集体中金属离子空间分布的详细知识，这对于理解微生物-矿物-金属相互作用的潜在机制至关重要。发现重金属（Au3+、Cd2+、Cr3+、CrO42−、Cu2+、Hg2+、Ni2+、Pd2+、三丁基锡 (TBT) 和 Zn2+）主要吸附在细胞表面，存在于复合糖基质内，并与矿物表面结合，但未并入生物 Fe(III) 矿物中。统计分析表明，测试的所有十种重金属均表现出相对相似的吸附行为，该行为受到吸附的亚铁和三价铁的影响。这项研究的结果表明，除了矿物质表面之外，细菌细胞表面和复合糖提供了重金属的大部分吸附位点。同时，亚铁离子和三价铁离子与重金属竞争有机化合物上的吸附位点。总之，使用微生物模型系统通过本方法获得的信息为更好地理解复杂自然环境中重金属和生物膜以及微生物形成的 Fe(III) 矿物质和重金属之间的相互作用提供了重要信息。
Aggregates consisting of bacterial cells, extracellular polymeric substances (EPS) and Fe(III) minerals formed by Fe(II)-oxidizing bacteria are common at bulk or microscale chemical interfaces where Fe cycling occurs. The high sorption capacity and binding capacity of cells, EPS, and minerals controls the mobility and fate of heavy metals. However, it remains unclear to which of these component(s) the metals will bind in complex aggregates. To clarify this question, the present study focuses on 3D mapping of heavy metals sorbed to cells, glycoconjugates that comprise the majority of EPS constituents, and Fe(III) mineral aggregates formed by the phototrophic Fe(II)-oxidizing bacteriaRhodobacter ferrooxidansSW2 using confocal laser scanning microscopy (CLSM) in combination with metal- and glycoconjugates-specific fluorophores. The present study evaluated the influence of glycoconjugates, microbial cell surfaces, and (biogenic) Fe(III) minerals, and the availability of ferrous and ferric iron on heavy metal sorption. Analyses in this study provide detailed knowledge on the spatial distribution of metal ions in the aggregates at the sub-μm scale, which is essential to understand the underlying mechanisms of microbe–mineral–metal interactions. The heavy metals (Au3+, Cd2+, Cr3+, CrO42−, Cu2+, Hg2+, Ni2+, Pd2+, tributyltin (TBT) and Zn2+) were found mainly sorbed to cell surfaces, present within the glycoconjugates matrix, and bound to the mineral surfaces, but not incorporated into the biogenic Fe(III) minerals. Statistical analysis revealed that all ten heavy metals tested showed relatively similar sorption behavior that was affected by the presence of sorbed ferrous and ferric iron. Results in this study showed that in addition to the mineral surfaces, both bacterial cell surfaces and the glycoconjugates provided most of sorption sites for heavy metals. Simultaneously, ferrous and ferric iron ions competed with the heavy metals for sorption sites on the organic compounds. In summary, the information obtained by the present approach using a microbial model system provides important information to better understand the interactions between heavy metals and biofilms, and microbially formed Fe(III) minerals and heavy metals in complex natural environments.