首页|Sulfur in humin as a redox-active element for extracellular electron transfer
Sulfur in humin as a redox-active element for extracellular electron transfer
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NSTL
Elsevier
? 2021 Elsevier B.V.Humin (HM), an insoluble humic substance that occurs as an organo-mineral complex, mediates extracellular electron transfer (EET) among microorganisms in the geosphere. Although sulfur (S)-containing functional groups have been posited as possible redox-active groups in HM, there has been no direct evidence in this regard. Here, we characterized the redox-active S in HM from different natural sources using synchrotron radiation-based X-ray absorption spectroscopy in partial fluorescence yield mode. The S content in HM is less than 0.9%, with the oxidation states ranged widely from ?2 to +6. About 9% to 19% of total S in HM was redox variable, corresponding to 1.2 × 10?5 to 17.1 × 10?5 Eq/g-HM redox capacity. The redox capacity of HM driven by S is comparable to or larger than the electron donating capacity of HM observed in anaerobic microbial dechlorination of pentachlorophenol, suggesting that S is one of the significant redox-active elements in HM. These findings provide new insights into the role of S cycling in biogeochemical processes and microbial energy networks.
Electron donating capacityExtracellular electron transferHuminMicrobial reductive dechlorinationRedox-active sulfurX-ray absorption fine structure
Pham D.M.、Yagi S.、Katayama A.、Oji H.、Ogawa S.
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Institute of Materials and Systems for Sustainability Nagoya University
Synchrotron Radiation Research Center Nagoya University
Department of Energy Engineering Graduate School of Engineering Nagoya University
NSTL
Elsevier
