Electron shuttle-mediated microbial Fe(III) reduction under alkaline conditions

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	Electron shuttle-mediated microbial Fe(III) reduction under alkaline conditions
	Li, Xiao-Ming; Wang, Xin-Nan; Sun, Guo-Xin; Zhu, Yong-Guan; Clarke, Thomas A.
刊名	JOURNAL OF SOILS AND SEDIMENTS
	2018
卷号	18 期号:1 页码:159-168
关键词	Alkaline conditions AQDS and sulfur Electron shuttles Humic substances Microbial Fe(III) reduction Usable thermodynamic energy
ISSN号	1439-0108
文献子类	Article
英文摘要	Extracellular Fe(III) reduction plays an important role in a variety of biogeochemical processes. Several mechanisms for microbial Fe(III) reduction in pH-neutral environments have been proposed, but pathways of microbial Fe(III) reduction within alkaline conditions have not been clearly identified. Alkaline soils are vastly distributed; thus, a better understanding of microbial Fe(III) reduction under alkaline conditions is of significance. The purpose of this study is to explore the dominant mechanism of bacterial iron reduction in alkaline environments. We used antraquinone-2,6-disulfonate (AQDS) as a representative of quinone moities of humic substances and elemental sulfur and sulfate as sulfur species to investigate the potential role of humic substances and sulfur species in mediating microbial Fe(III) reduction in alkaline environments. We carried out thermodynamic calculations to predict the ability of bacteria to reduce Fe(III) (oxyhydr)oxides under alkaline conditions and the ability of AQDS and sulfur species to serve as electron acceptors for microbial anaerobic respiration in an assumed alkaline soil environments. A series of incubation experiments with two model dissimilatory metal reducing bacteria, Shewanella oneidensis MR-1 and Geobacter sulfurreducens PCA as well as mixed bacteria enriched from a soil were performed to confirm the contribution of AQDS and sulfur species to Fe(III) reduction under alkaline conditions. Based on thermodynamic calculations, we predicted that, under alkaline conditions, the enzymatic reduction of Fe(III) (oxyhydr)oxides would be thermodynamically feasible but very weak. In our incubation experiments, the reduction of ferrihydrite by anaerobic cultures of Shewanella oneidensis MR-1, Geobacter sulfurreducens PCA or microbes enriched from a soil was significantly increased in the presence of S-0 or AQDS. Notably, AQDS contributed more to promoting Fe(III) reduction as a soluble electron shuttle than S-0 did under the alkaline conditions probably because of different mechanisms of microbial utilization of AQDS and S-0. These results suggest that microbial reduction of Fe(III) (oxyhydr)oxides under alkaline conditions may proceed via a pathway mediated by electron shuttles such as AQDS and S-0. Considering the high ability of electron shuttling and vast distribution of humic substances, we suggest that humic substance-mediated Fe(III) reduction may potentially be the dominant mechanism for Fe(III) reduction in alkaline environments.
内容类型	期刊论文
源URL	[http://ir.rcees.ac.cn/handle/311016/40541]
专题	生态环境研究中心_城市与区域生态国家重点实验室
推荐引用方式 GB/T 7714	Li, Xiao-Ming,Wang, Xin-Nan,Sun, Guo-Xin,et al. Electron shuttle-mediated microbial Fe(III) reduction under alkaline conditions[J]. JOURNAL OF SOILS AND SEDIMENTS,2018,18(1):159-168.
APA	Li, Xiao-Ming,Wang, Xin-Nan,Sun, Guo-Xin,Zhu, Yong-Guan,&Clarke, Thomas A..(2018).Electron shuttle-mediated microbial Fe(III) reduction under alkaline conditions.JOURNAL OF SOILS AND SEDIMENTS,18(1),159-168.
MLA	Li, Xiao-Ming,et al."Electron shuttle-mediated microbial Fe(III) reduction under alkaline conditions".JOURNAL OF SOILS AND SEDIMENTS 18.1(2018):159-168.