Selective retention of extracellular polymeric substances induced by adsorption to and coprecipitation with ferrihydrite
Selective retention of extracellular polymeric substances induced by adsorption to and coprecipitation with ferrihydrite
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通过与水铁矿的吸附和共沉淀诱导细胞外聚合物的选择性保留
DOI：
10.1016/j.gca.2021.02.015
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发表时间：
2021-04
影响因子：
5
通讯作者：
Qiaoyun Huang
中科院分区：
文献类型：
--
作者：
Ming Zhang;Caroline L. Peacock;Peng Cai;Ke-Qing Xiao;Chenchen Qu;Yichao Wu;Qiaoyun Huang
最近的研究表明，微生物衍生化合物构成了土壤有机质（OM）库的重要组成部分。这些化合物包括胞外聚合物（EPS），其质量可远远超过总微生物细胞生物量。EPS对土壤矿物质的吸附通过吸附和共沉淀发生，并有助于OM在土壤环境中的保存。然而，鲜为人知的是，关于EPS的吸附机制和选择性保留不同的EPS成分铁（oxyhydr）氧化物，特别是在EPS吸附与这些活性土壤相共沉淀。本研究探讨如何EPS与无处不在的土壤铁（oxyhydr）氧化物ferrihydrite在EPS吸附和共沉淀，以及这些不同的EPS矿物协会的途径是否影响EPS吸附和选择性保留，从而在土壤环境中的微生物来源的OM的流动性和命运。我们使用几种补充技术来i）检查EPS-碳、EPS-氮和EPS-磷吸附和分馏，ii）使用共聚焦激光扫描显微镜（CLSM）可视化EPS生物分子类别和水铁矿之间的空间关系，iii）使用X射线光电子能谱（XPS）和近边缘X射线吸收精细结构谱（NEXAFS）确定EPS-C形态和水铁矿的化学分馏，和iv）使用傅里叶变换红外光谱（FTIR）结合二维相关光谱（2D-COS）分析确定官能团与水铁矿的相互作用。结果表明，EPS的共沉淀并不改变作为EPS缔合的主要矿物相的水铁矿的矿物学，但它大大增加了EPS-水铁矿的粒度。在初始C/Fe摩尔比> 1时，在吸附和共沉淀实验之间观察到与水铁矿相关的EPS质量分数的显著差异。在吸附过程中EPS-N相对富集，而在共沉淀过程中，更多的EPS-C和接近完全的EPS-P被固定。XPS结果表明，通过EPS吸附形成的水铁矿的表面优先富集蛋白质类组分，而通过EPS共沉淀形成的水铁矿的表面富集多糖类组分，这是直观地证实了与CLSM图像。NEXAFS的结果表明，羧酸/酰胺含C的组分被选择性地保留在吸附过程中，与脂肪族和O-烷基含C的组分相对富集在共沉淀过程中。2D-FTIR-COS结果表明，EPS在水铁矿上吸附过程中，P双键O官能团的吸附速度快于酰胺和羧酸官能团，而EPS与水铁矿共沉淀过程中则相反.研究结果表明，EPS-水铁矿缔合物的形成途径显著影响EPS的吸附机制和选择性保留，从而影响微生物来源的碳（C）、氮（N）和磷（P）在土壤中的迁移和归宿。这些关于EPS在矿物质-水界面的行为的新见解可用于评估铁（羟基）氧化物如何稳定微生物衍生的化合物，如EPS，以及EPS-铁（羟基）氧化物耦合如何影响OM在自然环境中的反应性和循环。
Recent work shows that microbially-derived compounds constitute a significant fraction of the soil organic matter (OM) pool. These compounds include extracellular polymeric substances (EPS) whose mass can far exceed total microbial cell biomass. Sorption of EPS to soil minerals occurs via adsorption and coprecipitation and contributes to the preservation of OM in the soil environment. Little is known, however, about the sorption mechanisms of EPS and selective retention of different EPS constituents on iron (oxyhydr)oxides, especially during EPS adsorption versus coprecipitation with these reactive soil phases. This study examines how EPS interacts with the ubiquitous soil iron (oxyhydr)oxide ferrihydrite during EPS adsorption and coprecipitation and whether these different EPS-mineral association pathways affect EPS sorption and selective retention, and thus the mobility and fate of microbially-derived OM in the soil environment. We use several complimentary techniques to i) examine EPS-carbon, EPS-nitrogen and EPS-phosphorus sorption and fractionation, ii) visualize spatial relationships between EPS biomolecular classes and ferrihydrite using confocal laser scanning microscopy (CLSM), iii) determine EPS-C speciation and chemical fractionation with ferrihydrite using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and iv) determine functional group interactions with ferrihydrite using Fourier transform infrared spectroscopy (FTIR) combined with two-dimensional correlation spectroscopy (2D-COS) analysis. Results show that the coprecipitation of EPS does not change the ferrihydrite mineralogy, as the main mineral phase for EPS association, but it substantially increases the particle size of EPS-ferrihydrite. A substantial difference in the EPS mass fraction associated with the ferrihydrite is observed between the adsorption and coprecipitation experiments at an initial molar C/Fe ratio >1. The EPS-N is relatively enriched during the adsorption process, while more EPS-C and near-complete EPS-P are fixed in the coprecipitation process. XPS results show that the surface of the ferrihydrite formed through EPS adsorption is preferentially enriched with protein-like components, whereas, the surface of the ferrihydrite formed through EPS coprecipitation is enriched with polysaccharide-like components, which is visually confirmed with CLSM images. NEXAFS results reveal that the carboxylic/amide C-containing components are selectively retained during adsorption, with the aliphatic and O-alkyl C-containing components relatively enriched during coprecipitation. 2D-FTIR-COS results indicate that during EPS adsorption on ferrihydrite the Pdouble bondO functional groups are adsorbed faster than the amide and carboxylate functional groups, while during EPS coprecipitation with ferrihydrite the opposite trend is observed. The findings from this study indicate that the formation pathway of EPS-ferrihydrite associations substantially effects the sorption mechanisms and selective retention of EPS and may thus affect the mobility and fate of microbially-derived carbon (C), nitrogen (N) and phosphorus (P) in soils. These new insights on EPS behaviour at the mineral–water interface might be used to evaluate how microbially-derived compounds like EPS are stabilized by iron (oxyhydr)oxides and how EPS-iron (oxyhydr)oxide couplings might affect the reactivity and cycling of OM in natural environments.
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影响因子：
4.6
作者：
Adhikari D;Yang Y
通讯作者：
Yang Y
土壤生物膜的形成增强微生物群落多样性和代谢活性
影响因子：
11.8
作者：
Wu Yichao;Cai Peng;Jing Xinxin;Niu Xueke;Ji D;an;Ashry Noha Mohamed;Gao Chunhui;Huang Qiaoyun
通讯作者：
Huang Qiaoyun
DOI：
10.32388/iwu90g
发表时间：
2020-02
期刊：
Definitions
影响因子：
--
作者：
Larissa Krüger;C. Herzberg;Hermann Rath;Tiago Pedreira;Anja Poehlein;J. Gundlach;R. Daniel;U. Völker-U.
通讯作者：
Larissa Krüger;C. Herzberg;Hermann Rath;Tiago Pedreira;Anja Poehlein;J. Gundlach;R. Daniel;U. Völker-U.
影响因子：
3.9
作者：
P. Cai;Di Lin;C. Peacock;W. Peng;Qiaoyun Huang
通讯作者：
P. Cai;Di Lin;C. Peacock;W. Peng;Qiaoyun Huang
影响因子：
11.4
作者：
A. Simpson;M. Simpson;E. Smith;B. Kelleher
通讯作者：
A. Simpson;M. Simpson;E. Smith;B. Kelleher