School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, China.
School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, China.
J Environ Sci (China). 2022 Oct;120:115-124. doi: 10.1016/j.jes.2021.08.043. Epub 2022 Feb 1.
Vivianite is often found in reducing environments rich in iron and phosphorus from organic debris degradation or phosphorus mineral dissolution. The formation of vivianite is essential to the geochemical cycling of phosphorus and iron elements in natural environments. In this study, extracellular polymeric substances (EPS) were selected as the source of phosphorus. Microcosm experiments were conducted to test the evolution of mineralogy during the reduction of polyferric sulfate flocs (PFS) by Shewanella oneidensis MR-1 (S. oneidensis MR-1) at EPS concentrations of 0, 0.03, and 0.3 g/L. Vivianite was found to be the secondary mineral in EPS treatment when there was no phosphate in the media. The EPS DNA served as the phosphorus source and DNA-supplied phosphate could induce the formation of vivianite. EPS impedes PFS aggregation, contains redox proteins and stores electron shuttle, and thus greatly promotes the formation of minerals and enhances the reduction of Fe(III). At EPS concentration of 0, 0.03, and 0.3 g/L, the produced HCl-extractable Fe(II) was 107.9, 111.0, and 115.2 mg/L, respectively. However, when the microcosms remained unstirred, vivianite can be formed without the addition of EPS. In unstirred systems, the EPS secreted by S. oneidensis MR-1 could agglomerate at some areas, resulting in the formation of vivianite in the proximity of microbial cells. It was found that vivianite can be generated biogenetically by S. oneidensis MR-1 strain and EPS may play a key role in iron reduction and concentrating phosphorus in the oligotrophic ecosystems where quiescent conditions prevail.
水磷铁矿通常在富含铁和磷的还原环境中形成，这些环境来自有机碎屑的降解或磷矿物的溶解。水磷铁矿的形成对于自然环境中铁和磷元素的地球化学循环至关重要。在本研究中，选择胞外聚合物（EPS）作为磷源。通过希瓦氏菌（Shewanella oneidensis MR-1）还原聚硫酸铁絮体（PFS）的微宇宙实验，测试了 EPS 浓度分别为 0、0.03 和 0.3 g/L 时，矿物学的演变。在没有磷酸盐的培养基中，发现 EPS 处理时的次生矿物为水磷铁矿。EPS DNA 作为磷源，提供的 DNA 磷酸盐可以诱导水磷铁矿的形成。EPS 阻碍了 PFS 的聚集，含有氧化还原蛋白并储存电子穿梭体，从而极大地促进了矿物的形成并增强了 Fe(III)的还原。在 EPS 浓度为 0、0.03 和 0.3 g/L 时，产生的 HCl 可提取 Fe(II)分别为 107.9、111.0 和 115.2 mg/L。然而，当微宇宙不搅拌时，即使不添加 EPS 也可以形成水磷铁矿。在不搅拌的系统中，希瓦氏菌（Shewanella oneidensis MR-1）分泌的 EPS 可能会在某些区域聚集，导致在微生物细胞附近形成水磷铁矿。研究发现，水磷铁矿可以由希瓦氏菌（Shewanella oneidensis MR-1）菌株生物合成，并且 EPS 可能在寡营养生态系统中（即静止条件下）的铁还原和磷浓缩中发挥关键作用。
