Cargando…
Mediation of Extracellular Polymeric Substances in Microbial Reduction of Hematite by Shewanella oneidensis MR-1
Extracellular electron transfer (EET) plays a fundamental role in microbial reduction/oxidation of minerals. Extracellular polymeric substances (EPS) surrounding the cells constitute a matrix that separates the cell’s outer membrane from insoluble minerals and environmental fluid. This study investi...
Autores principales: | , , , , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Frontiers Media S.A.
2019
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6449630/ https://www.ncbi.nlm.nih.gov/pubmed/30984128 http://dx.doi.org/10.3389/fmicb.2019.00575 |
_version_ | 1783408890477543424 |
---|---|
author | Gao, Lei Lu, Xiancai Liu, Huan Li, Juan Li, Weijie Song, Rongbin Wang, Ruiyong Zhang, Dongmei Zhu, Junjie |
author_facet | Gao, Lei Lu, Xiancai Liu, Huan Li, Juan Li, Weijie Song, Rongbin Wang, Ruiyong Zhang, Dongmei Zhu, Junjie |
author_sort | Gao, Lei |
collection | PubMed |
description | Extracellular electron transfer (EET) plays a fundamental role in microbial reduction/oxidation of minerals. Extracellular polymeric substances (EPS) surrounding the cells constitute a matrix that separates the cell’s outer membrane from insoluble minerals and environmental fluid. This study investigated the effects of EPS on EET processes during microbial reduction of hematite by the iron-reducing strain Shewanella oneidensis MR-1 (MR-1). Electrochemical characterization techniques were employed to determine the influence of EPS components on the redox ability of MR-1. Cells with removed EPS exhibited approximately 30% higher hematite reduction than regular MR-1 cells, and produced a current density of 56 μA cm(-2), corresponding to 3–4 fold that of regular MR-1. The superior EET of EPS-deprived cells could be attributed to direct contact between outer membrane proteins and hematite surface, as indicated by more redox peaks being detected by cyclic voltammetry and differential pulse voltammetry. The significantly reduced current density of MR-1 cells treated with proteinase K and deoxyribonuclease suggests that the electron transfer capacity across the EPS layer depends mainly on the spatial distribution of specific proteins and electron shuttles. Exopolysaccharides in EPS tend to inhibit electron transfer, however they also favor the attachment of cells onto hematite surfaces. Consistently, the charge transfer resistance of cells lacking EPS was only 116.3 Ω, approximately 44 times lower than that of regular cells (5,139.1 Ω). These findings point to a negative influence of EPS on EET processes for microbial reduction/oxidation of minerals. |
format | Online Article Text |
id | pubmed-6449630 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-64496302019-04-12 Mediation of Extracellular Polymeric Substances in Microbial Reduction of Hematite by Shewanella oneidensis MR-1 Gao, Lei Lu, Xiancai Liu, Huan Li, Juan Li, Weijie Song, Rongbin Wang, Ruiyong Zhang, Dongmei Zhu, Junjie Front Microbiol Microbiology Extracellular electron transfer (EET) plays a fundamental role in microbial reduction/oxidation of minerals. Extracellular polymeric substances (EPS) surrounding the cells constitute a matrix that separates the cell’s outer membrane from insoluble minerals and environmental fluid. This study investigated the effects of EPS on EET processes during microbial reduction of hematite by the iron-reducing strain Shewanella oneidensis MR-1 (MR-1). Electrochemical characterization techniques were employed to determine the influence of EPS components on the redox ability of MR-1. Cells with removed EPS exhibited approximately 30% higher hematite reduction than regular MR-1 cells, and produced a current density of 56 μA cm(-2), corresponding to 3–4 fold that of regular MR-1. The superior EET of EPS-deprived cells could be attributed to direct contact between outer membrane proteins and hematite surface, as indicated by more redox peaks being detected by cyclic voltammetry and differential pulse voltammetry. The significantly reduced current density of MR-1 cells treated with proteinase K and deoxyribonuclease suggests that the electron transfer capacity across the EPS layer depends mainly on the spatial distribution of specific proteins and electron shuttles. Exopolysaccharides in EPS tend to inhibit electron transfer, however they also favor the attachment of cells onto hematite surfaces. Consistently, the charge transfer resistance of cells lacking EPS was only 116.3 Ω, approximately 44 times lower than that of regular cells (5,139.1 Ω). These findings point to a negative influence of EPS on EET processes for microbial reduction/oxidation of minerals. Frontiers Media S.A. 2019-03-29 /pmc/articles/PMC6449630/ /pubmed/30984128 http://dx.doi.org/10.3389/fmicb.2019.00575 Text en Copyright © 2019 Gao, Lu, Liu, Li, Li, Song, Wang, Zhang and Zhu. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Microbiology Gao, Lei Lu, Xiancai Liu, Huan Li, Juan Li, Weijie Song, Rongbin Wang, Ruiyong Zhang, Dongmei Zhu, Junjie Mediation of Extracellular Polymeric Substances in Microbial Reduction of Hematite by Shewanella oneidensis MR-1 |
title | Mediation of Extracellular Polymeric Substances in Microbial Reduction of Hematite by Shewanella oneidensis MR-1 |
title_full | Mediation of Extracellular Polymeric Substances in Microbial Reduction of Hematite by Shewanella oneidensis MR-1 |
title_fullStr | Mediation of Extracellular Polymeric Substances in Microbial Reduction of Hematite by Shewanella oneidensis MR-1 |
title_full_unstemmed | Mediation of Extracellular Polymeric Substances in Microbial Reduction of Hematite by Shewanella oneidensis MR-1 |
title_short | Mediation of Extracellular Polymeric Substances in Microbial Reduction of Hematite by Shewanella oneidensis MR-1 |
title_sort | mediation of extracellular polymeric substances in microbial reduction of hematite by shewanella oneidensis mr-1 |
topic | Microbiology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6449630/ https://www.ncbi.nlm.nih.gov/pubmed/30984128 http://dx.doi.org/10.3389/fmicb.2019.00575 |
work_keys_str_mv | AT gaolei mediationofextracellularpolymericsubstancesinmicrobialreductionofhematitebyshewanellaoneidensismr1 AT luxiancai mediationofextracellularpolymericsubstancesinmicrobialreductionofhematitebyshewanellaoneidensismr1 AT liuhuan mediationofextracellularpolymericsubstancesinmicrobialreductionofhematitebyshewanellaoneidensismr1 AT lijuan mediationofextracellularpolymericsubstancesinmicrobialreductionofhematitebyshewanellaoneidensismr1 AT liweijie mediationofextracellularpolymericsubstancesinmicrobialreductionofhematitebyshewanellaoneidensismr1 AT songrongbin mediationofextracellularpolymericsubstancesinmicrobialreductionofhematitebyshewanellaoneidensismr1 AT wangruiyong mediationofextracellularpolymericsubstancesinmicrobialreductionofhematitebyshewanellaoneidensismr1 AT zhangdongmei mediationofextracellularpolymericsubstancesinmicrobialreductionofhematitebyshewanellaoneidensismr1 AT zhujunjie mediationofextracellularpolymericsubstancesinmicrobialreductionofhematitebyshewanellaoneidensismr1 |