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Pulse electromagnetic fields enhance extracellular electron transfer in magnetic bioelectrochemical systems

BACKGROUND: Microbial extracellular electron transfer (EET) is essential in driving the microbial interspecies interaction and redox reactions in bioelectrochemical systems (BESs). Magnetite (Fe(3)O(4)) and magnetic fields (MFs) were recently reported to promote microbial EET, but the mechanisms of...

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Autores principales: Zhou, Huihui, Liu, Bingfeng, Wang, Qisong, Sun, Jianmin, Xie, Guojun, Ren, Nanqi, Ren, Zhiyong Jason, Xing, Defeng
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5644122/
https://www.ncbi.nlm.nih.gov/pubmed/29075322
http://dx.doi.org/10.1186/s13068-017-0929-3
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author Zhou, Huihui
Liu, Bingfeng
Wang, Qisong
Sun, Jianmin
Xie, Guojun
Ren, Nanqi
Ren, Zhiyong Jason
Xing, Defeng
author_facet Zhou, Huihui
Liu, Bingfeng
Wang, Qisong
Sun, Jianmin
Xie, Guojun
Ren, Nanqi
Ren, Zhiyong Jason
Xing, Defeng
author_sort Zhou, Huihui
collection PubMed
description BACKGROUND: Microbial extracellular electron transfer (EET) is essential in driving the microbial interspecies interaction and redox reactions in bioelectrochemical systems (BESs). Magnetite (Fe(3)O(4)) and magnetic fields (MFs) were recently reported to promote microbial EET, but the mechanisms of MFs stimulation of EET and current generation in BESs are not known. This study investigates the behavior of current generation and EET in a state-of-the-art pulse electromagnetic field (PEMF)-assisted magnetic BES (PEMF-MBES), which was equipped with magnetic carbon particle (Fe(3)O(4)@N-mC)-coated electrodes. Illumina Miseq sequencing of 16S rRNA gene amplicons was also conducted to reveal the changes of microbial communities and interactions on the anode in response to magnetic field. RESULTS: PEMF had significant influences on current generation. When reactors were operated in microbial fuel cell (MFC) mode with pulse electromagnetic field (PEMF-MMFCs), power densities increased by 25.3–36.0% compared with no PEMF control MFCs (PEMF-OFF-MMFCs). More interestingly, when PEMF was removed, the power density dropped by 25.7%, while when PEMF was reintroduced, the value was restored to the previous level. Illumina sequencing of 16S rRNA gene amplicon and principal component analysis (PCA) based on operational taxonomic units (OTUs) indicate that PEMFs led to the shifts in microbial community and changes in species evenness that decreased biofilm microbial diversity. Geobacter spp. were found dominant in all anode biofilms, but the relative abundance in PEMF-MMFCs (86.1–90.0%) was higher than in PEMF-OFF-MMFCs (82.5–82.7%), indicating that the magnetic field enriched Geobacter on the anode. The current generation of Geobacter-inoculated microbial electrolysis cells (MECs) presented the same change regularity, the accordingly increase or decrease corresponding with switch of PEMF, which confirmed the reversible stimulation of PEMFs on microbial electron transfer. CONCLUSION: The pulse electromagnetic field (PEMF) showed significant influence on state-of-the-art pulse magnetic bioelectrochemical systems (PEMF-MBES) in terms of current generation and microbial ecology. EET was instantaneously and reversibly enhanced in MBESs inoculated with either mixed-culture or Geobacter. PEMF notably decreased bacterial and archaeal diversities of the anode biofilms in MMFCs via changing species evenness rather than species richness, and facilitated specific enrichment of exoelectrogenic bacteria (Geobacter) on the anode surface. This study demonstrates a new magnetic approach for understanding and facilitating microbial electrochemical activities. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-017-0929-3) contains supplementary material, which is available to authorized users.
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spelling pubmed-56441222017-10-26 Pulse electromagnetic fields enhance extracellular electron transfer in magnetic bioelectrochemical systems Zhou, Huihui Liu, Bingfeng Wang, Qisong Sun, Jianmin Xie, Guojun Ren, Nanqi Ren, Zhiyong Jason Xing, Defeng Biotechnol Biofuels Research BACKGROUND: Microbial extracellular electron transfer (EET) is essential in driving the microbial interspecies interaction and redox reactions in bioelectrochemical systems (BESs). Magnetite (Fe(3)O(4)) and magnetic fields (MFs) were recently reported to promote microbial EET, but the mechanisms of MFs stimulation of EET and current generation in BESs are not known. This study investigates the behavior of current generation and EET in a state-of-the-art pulse electromagnetic field (PEMF)-assisted magnetic BES (PEMF-MBES), which was equipped with magnetic carbon particle (Fe(3)O(4)@N-mC)-coated electrodes. Illumina Miseq sequencing of 16S rRNA gene amplicons was also conducted to reveal the changes of microbial communities and interactions on the anode in response to magnetic field. RESULTS: PEMF had significant influences on current generation. When reactors were operated in microbial fuel cell (MFC) mode with pulse electromagnetic field (PEMF-MMFCs), power densities increased by 25.3–36.0% compared with no PEMF control MFCs (PEMF-OFF-MMFCs). More interestingly, when PEMF was removed, the power density dropped by 25.7%, while when PEMF was reintroduced, the value was restored to the previous level. Illumina sequencing of 16S rRNA gene amplicon and principal component analysis (PCA) based on operational taxonomic units (OTUs) indicate that PEMFs led to the shifts in microbial community and changes in species evenness that decreased biofilm microbial diversity. Geobacter spp. were found dominant in all anode biofilms, but the relative abundance in PEMF-MMFCs (86.1–90.0%) was higher than in PEMF-OFF-MMFCs (82.5–82.7%), indicating that the magnetic field enriched Geobacter on the anode. The current generation of Geobacter-inoculated microbial electrolysis cells (MECs) presented the same change regularity, the accordingly increase or decrease corresponding with switch of PEMF, which confirmed the reversible stimulation of PEMFs on microbial electron transfer. CONCLUSION: The pulse electromagnetic field (PEMF) showed significant influence on state-of-the-art pulse magnetic bioelectrochemical systems (PEMF-MBES) in terms of current generation and microbial ecology. EET was instantaneously and reversibly enhanced in MBESs inoculated with either mixed-culture or Geobacter. PEMF notably decreased bacterial and archaeal diversities of the anode biofilms in MMFCs via changing species evenness rather than species richness, and facilitated specific enrichment of exoelectrogenic bacteria (Geobacter) on the anode surface. This study demonstrates a new magnetic approach for understanding and facilitating microbial electrochemical activities. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13068-017-0929-3) contains supplementary material, which is available to authorized users. BioMed Central 2017-10-16 /pmc/articles/PMC5644122/ /pubmed/29075322 http://dx.doi.org/10.1186/s13068-017-0929-3 Text en © The Author(s) 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Zhou, Huihui
Liu, Bingfeng
Wang, Qisong
Sun, Jianmin
Xie, Guojun
Ren, Nanqi
Ren, Zhiyong Jason
Xing, Defeng
Pulse electromagnetic fields enhance extracellular electron transfer in magnetic bioelectrochemical systems
title Pulse electromagnetic fields enhance extracellular electron transfer in magnetic bioelectrochemical systems
title_full Pulse electromagnetic fields enhance extracellular electron transfer in magnetic bioelectrochemical systems
title_fullStr Pulse electromagnetic fields enhance extracellular electron transfer in magnetic bioelectrochemical systems
title_full_unstemmed Pulse electromagnetic fields enhance extracellular electron transfer in magnetic bioelectrochemical systems
title_short Pulse electromagnetic fields enhance extracellular electron transfer in magnetic bioelectrochemical systems
title_sort pulse electromagnetic fields enhance extracellular electron transfer in magnetic bioelectrochemical systems
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5644122/
https://www.ncbi.nlm.nih.gov/pubmed/29075322
http://dx.doi.org/10.1186/s13068-017-0929-3
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