Surface Analysis of Coal Indicating Neutral Red Enhances the Precursor Steps of Methanogenesis
Artificially stimulated, high-yield microbial production of methane from coal is a challenging problem that continues to generate research interest. Decomposition of organic matter and production of methane from coal are the results of multiple redox reactions carried out by different communities of...
Main Authors: | , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Frontiers Media S.A.
2020-11-01
|
Series: | Frontiers in Microbiology |
Subjects: | |
Online Access: | https://www.frontiersin.org/articles/10.3389/fmicb.2020.586917/full |
id |
doaj-4a8f6c65a3324f7d936813172730a4f4 |
---|---|
record_format |
Article |
spelling |
doaj-4a8f6c65a3324f7d936813172730a4f42020-11-25T03:56:59ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2020-11-011110.3389/fmicb.2020.586917586917Surface Analysis of Coal Indicating Neutral Red Enhances the Precursor Steps of MethanogenesisPriyanka Srivastava0Christopher Marjo1Alireza Gerami2Zackary Jones3Sheik Rahman4School of Chemical Engineering, University of New South Wales, Sydney, NSW, AustraliaMark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW, AustraliaSchool of Minerals and Mining, University of New South Wales, Sydney, NSW, AustraliaSchool of Chemical Engineering, University of New South Wales, Sydney, NSW, AustraliaSchool of Minerals and Mining, University of New South Wales, Sydney, NSW, AustraliaArtificially stimulated, high-yield microbial production of methane from coal is a challenging problem that continues to generate research interest. Decomposition of organic matter and production of methane from coal are the results of multiple redox reactions carried out by different communities of bacteria and archaea. Recent work by our group (Beckmann et al., 2015) demonstrated that the presence of the redox-mediating molecule neutral red, in its crystalline form on a coal surface, can increase methane production. However, hydrolysis and the acetogenesis of the coal surface are essential precursor steps for methane production by archaea. Acetogenesis is the preparation phase of methanogenesis because methanogens can only assimilate acetate, CO2 and H2 among the products formed during this process. In the present study, the surface chemical analysis of neutral red treated coal using attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) demonstrate that the acetate production and resulting oxidation of the coal only occurred at few nanometers into the coal surface (at the nanoscale <5 nm). We observed that in the presence of neutral red and groundwater microbes, acetate signals in coal surface chemistry increased. This is the first evidence suggesting that neutral red enhances the biological conversion of coal into acetate. Microscopy demonstrated that neutral red crystals were co-localize with cells at the surface of coal in groundwater. This is consistent with neutral red crystals serving as a redox hub, concentrating and distributing reducing equivalents amongst the microbial community. In this study, the chemical changes of neutral red treated coal indicated that neutral red doubles the concentration of acetate over the control (coal without neutral red), emphasizing the importance of maximizing the fracture surface coverage of this redox mediator. Overall, results suggested that, neutral red not only can benefit acetoclastic methanogens, but also the fermentative and acetogenic bacteria involved in generating acetate.https://www.frontiersin.org/articles/10.3389/fmicb.2020.586917/fullcoalneutral redredox mediatorsacetogensmethanogenesisattenuated total reflectance-fourier transform infrared |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Priyanka Srivastava Christopher Marjo Alireza Gerami Zackary Jones Sheik Rahman |
spellingShingle |
Priyanka Srivastava Christopher Marjo Alireza Gerami Zackary Jones Sheik Rahman Surface Analysis of Coal Indicating Neutral Red Enhances the Precursor Steps of Methanogenesis Frontiers in Microbiology coal neutral red redox mediators acetogens methanogenesis attenuated total reflectance-fourier transform infrared |
author_facet |
Priyanka Srivastava Christopher Marjo Alireza Gerami Zackary Jones Sheik Rahman |
author_sort |
Priyanka Srivastava |
title |
Surface Analysis of Coal Indicating Neutral Red Enhances the Precursor Steps of Methanogenesis |
title_short |
Surface Analysis of Coal Indicating Neutral Red Enhances the Precursor Steps of Methanogenesis |
title_full |
Surface Analysis of Coal Indicating Neutral Red Enhances the Precursor Steps of Methanogenesis |
title_fullStr |
Surface Analysis of Coal Indicating Neutral Red Enhances the Precursor Steps of Methanogenesis |
title_full_unstemmed |
Surface Analysis of Coal Indicating Neutral Red Enhances the Precursor Steps of Methanogenesis |
title_sort |
surface analysis of coal indicating neutral red enhances the precursor steps of methanogenesis |
publisher |
Frontiers Media S.A. |
series |
Frontiers in Microbiology |
issn |
1664-302X |
publishDate |
2020-11-01 |
description |
Artificially stimulated, high-yield microbial production of methane from coal is a challenging problem that continues to generate research interest. Decomposition of organic matter and production of methane from coal are the results of multiple redox reactions carried out by different communities of bacteria and archaea. Recent work by our group (Beckmann et al., 2015) demonstrated that the presence of the redox-mediating molecule neutral red, in its crystalline form on a coal surface, can increase methane production. However, hydrolysis and the acetogenesis of the coal surface are essential precursor steps for methane production by archaea. Acetogenesis is the preparation phase of methanogenesis because methanogens can only assimilate acetate, CO2 and H2 among the products formed during this process. In the present study, the surface chemical analysis of neutral red treated coal using attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) demonstrate that the acetate production and resulting oxidation of the coal only occurred at few nanometers into the coal surface (at the nanoscale <5 nm). We observed that in the presence of neutral red and groundwater microbes, acetate signals in coal surface chemistry increased. This is the first evidence suggesting that neutral red enhances the biological conversion of coal into acetate. Microscopy demonstrated that neutral red crystals were co-localize with cells at the surface of coal in groundwater. This is consistent with neutral red crystals serving as a redox hub, concentrating and distributing reducing equivalents amongst the microbial community. In this study, the chemical changes of neutral red treated coal indicated that neutral red doubles the concentration of acetate over the control (coal without neutral red), emphasizing the importance of maximizing the fracture surface coverage of this redox mediator. Overall, results suggested that, neutral red not only can benefit acetoclastic methanogens, but also the fermentative and acetogenic bacteria involved in generating acetate. |
topic |
coal neutral red redox mediators acetogens methanogenesis attenuated total reflectance-fourier transform infrared |
url |
https://www.frontiersin.org/articles/10.3389/fmicb.2020.586917/full |
work_keys_str_mv |
AT priyankasrivastava surfaceanalysisofcoalindicatingneutralredenhancestheprecursorstepsofmethanogenesis AT christophermarjo surfaceanalysisofcoalindicatingneutralredenhancestheprecursorstepsofmethanogenesis AT alirezagerami surfaceanalysisofcoalindicatingneutralredenhancestheprecursorstepsofmethanogenesis AT zackaryjones surfaceanalysisofcoalindicatingneutralredenhancestheprecursorstepsofmethanogenesis AT sheikrahman surfaceanalysisofcoalindicatingneutralredenhancestheprecursorstepsofmethanogenesis |
_version_ |
1724462495435849728 |