Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland, Gründenstrasse 40, 4132, Muttenz, Switzerland.
Institute for Environmental Research (Biology V), RWTH Aachen University, 52074, Aachen, Germany.
Appl Microbiol Biotechnol. 2018 Sep;102(17):7635-7641. doi: 10.1007/s00253-018-9165-4. Epub 2018 Jun 21.
The environmental fate of major (e.g. C, N, S, Fe and Mn) and trace (e.g. As, Cr, Sb, Se and U) elements is governed by microbially catalysed reduction-oxidation (redox) reactions. Mesocosms are routinely used to elucidate trace metal fate on the basis of correlations between biogeochemical proxies such as dissolved element concentrations, trace element speciation and dissolved organic matter. However, several redox processes may proceed simultaneously in natural soils and sediments (particularly, reductive Mn and Fe dissolution and metal/metalloid reduction), having a contrasting effect on element mobility. Here, a novel redox-stat (R) bioreactor allowed precise control of the redox potential (159 ± 11 mV, ~ 2 months), suppressing redox reactions thermodynamically favoured at lower redox potential (i.e. reductive mobilisation of Fe and As). For a historically contaminated mining soil, As release could be attributed to desorption of arsenite [As(III)] and Mn reductive dissolution. By contrast, the control bioreactor (R, with naturally developing redox potential) showed almost double As release (337 vs. 181 μg g) due to reductive dissolution of Fe (1363 μg g Fe released; no Fe detected in R) and microbial arsenate [As(V)] reduction (189 μg g released vs. 46 μg g As(III) in R). A redox-stat bioreactor thus represents a versatile tool to study processes underlying mobilisation and sequestration of other trace elements as well.
主要（如 C、N、S、Fe 和 Mn）和痕量（如 As、Cr、Sb、Se 和 U）元素的环境归宿受微生物催化的氧化还原（还原）反应控制。中观模型系统常用于根据生物地球化学示踪剂（如溶解元素浓度、痕量元素形态和溶解有机物）之间的相关性来阐明痕量金属的归宿。然而，在自然土壤和沉积物中，几种氧化还原过程可能同时进行（特别是还原 Mn 和 Fe 的溶解以及金属/类金属的还原），对元素的迁移性产生相反的影响。在这里，一种新颖的氧化还原状态（R）生物反应器可以精确控制氧化还原电位（159±11 mV，~2 个月），从热力学上抑制在较低氧化还原电位下有利的氧化还原反应（即 Fe 和 As 的还原移动）。对于一个历史上受到污染的采矿土壤，As 的释放可以归因于亚砷酸盐[As(III)]的解吸和 Mn 的还原溶解。相比之下，对照生物反应器（R，具有自然发展的氧化还原电位）由于 Fe 的还原溶解（释放 1363μg g Fe；R 中未检测到 Fe）和微生物砷酸盐[As(V)]还原（释放 189μg g，而 R 中只有 46μg g As(III)）导致 As 的释放几乎增加了一倍（337 对 181μg g）。因此，氧化还原状态生物反应器是一种研究其他痕量元素的迁移和固定过程的多功能工具。
