Direct Interspecies Electron Transfer (DIET) Mediated by Electrically Conductive Materials

Topic Information

Dear Colleagues,

Microbial communities are fundamental for the right functioning of biological-based treatment processes and energy recovery technologies. Particularly relevant is the role that microorganisms play in the oxidation of and reduction in key elements. Many of these reactions are carried out by different microbial species that work closely in the syntrophic relationship to drive otherwise energetically unfavorable reactions. The flow of electrons within these communities governs which reactions occur (thermodynamics) and their rates (kinetics).

Conventional models of electron transfer, frequently referred to as interspecies electron transfer (IET), incorporate the diffusion of metabolites generated by one organism (such as hydrogen gas and/or formate) and consumed by a second.

Another proposed mechanism, recently discovered, is direct interspecies electron transfer (DIET) through extracellular electron exchange between microorganisms or mediated by electro-conductive materials.

An increasing number of studies have suggested that DIET can be stimulated by the addition of conductive materials, both in natural (e.g., soils, sediments) and engineered systems (e.g., anaerobic digesters, bioelectrochemical-assisted wetlands, so-called METlands) where syntrophic relationships play a critical role.

In particular, the addition of natural conductive minerals (iron oxides, mainly magnetite) and carbon materials (granular activated carbon, biochar, graphite, carbon cloth and carbon felt tube electrode)  has, in many cases, improved electron transfer rates between microbial species, and/or between microbes and electrodes, by serving as electron conduits.

Up to now, most of the studies regarded the enhancement of DIET-based communities to accelerate and stabilize anaerobic digestion or enhance efficiency of constructed wetlands. More recently, numerous bioelectrochemical technologies are emerging from the ability of microorganisms to directly exchange electrons with electroconductive materials. Applications actively being investigated include the harvesting of electrical current from waste organic matter, electrobioremediation, microbial electrosynthesis, sensors, and biological computing. Most of these technologies are still in the early stages of development.

In this context, this Topic offers a framework for integrating interdisciplinary research, discussing the recent achievements in DIET mediated by minerals in all its aspects, and aims to understand the physiology and ecology of the process and its biogeochemical impact but also the potential practical applications.

Dr. Carolina Cruz Viggi
Dr. Federico Aulenta
Prof. Dr. Abraham Esteve-Núñez
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Minerals minerals	2.2	4.1	2011	18 Days	CHF 2400
Materials materials	3.1	5.8	2008	13.9 Days	CHF 2600
Microorganisms microorganisms	4.1	7.4	2013	11.7 Days	CHF 2700

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Published Papers (3 papers)

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11 pages, 2721 KiB  

Open AccessArticle

Natural Magnetite Minerals Enhance 1,2-Dichloroethane Reductive Dechlorination

by Patrícia Leitão, Matteo Tucci, Carolina Cruz Viggi, Henri Nouws, Anthony S. Danko and Federico Aulenta

Minerals 2022, 12(7), 816; https://doi.org/10.3390/min12070816 - 26 Jun 2022

Cited by 4 | Viewed by 2201

Abstract

Contamination of soil and groundwater by chlorinated solvents is an environmental issue of primary concern. Recently, electrically conductive iron particles have been proposed as a novel approach to accelerate anaerobic bioremediation processes. In fact, it was demonstrated that conductive particles facilitate the exchange [...] Read more.

Contamination of soil and groundwater by chlorinated solvents is an environmental issue of primary concern. Recently, electrically conductive iron particles have been proposed as a novel approach to accelerate anaerobic bioremediation processes. In fact, it was demonstrated that conductive particles facilitate the exchange of electrons between microorganisms via Direct Interspecies Electron Transfer (DIET) processes, thus enhancing the pollutant-degrading potential of the microbial community. However, the use of natural minerals in this context has not been reported so far. In this study, we applied, for the first time, natural magnetite and hematite to accelerate the reductive dechlorination of 1,2-dichloroethane by an enrichment culture in lab-scale anaerobic microcosms. After four feeding cycles, low magnetite-amended microcosms (13 mg/L) yielded the highest rate of 1,2-DCA reductive dechlorination and reduced methanogenic activity. By contrast, hematite did not display any apparent stimulatory effect. Surprisingly, in the presence of higher amounts of iron oxides, a weaker effect was obtained, probably because iron(III) present in the minerals competed for the electrons necessary for reductive dechlorination. For all microcosms, the concentration of the toxic byproduct vinyl chloride was negligible throughout the whole study. The SEM/EDS analysis confirmed the close interaction between the conductive iron oxide particles and the dechlorinating bacteria. This work opens the possibility of using natural conductive minerals for bioremediation applications as well as shedding light on the previously unrecognized role of such minerals in contaminated ecosystems. Full article

(This article belongs to the Topic Direct Interspecies Electron Transfer (DIET) Mediated by Electrically Conductive Materials)

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14 pages, 2802 KiB  

Open AccessArticle

The Effect of a Hydrogen Reduction Procedure on the Microbial Synthesis of a Nano-Pd Electrocatalyst for an Oxygen-Reduction Reaction

by Jingwen Huang, Guoqing Zhang, Xiaoting Deng, Qingxin Li, Haikun Zhou, Zhiyong Xie, Xueduan Liu, Feng Liu and Yili Liang

Minerals 2022, 12(5), 531; https://doi.org/10.3390/min12050531 - 24 Apr 2022

Cited by 1 | Viewed by 2128

Abstract

Noble-metal electrocatalysts supported by biological-organism-derived carbons have attracted attention from the public due to the growing demands for green synthesis and environmental protection. Carbonization at high temperatures and hydrogen reduction are critical steps in this technical route. Herein, Shewanella oneidensis MR-1 were used [...] Read more.

Noble-metal electrocatalysts supported by biological-organism-derived carbons have attracted attention from the public due to the growing demands for green synthesis and environmental protection. Carbonization at high temperatures and hydrogen reduction are critical steps in this technical route. Herein, Shewanella oneidensis MR-1 were used as precursors, and the effects of the hydrogen-reduction procedure on catalysts were explored. The results showed that the performances of FHTG (carbonization followed by hydrogen reduction) displayed the best performance. Its ECSA (electrochemical surface area), MA (mass activity), and SA (specific activity) reached 35.01 m² g⁻¹, 58.39 A·g⁻¹, and 1.66 A cm⁻², respectively, which were 1.17, 1.75, and 1.50 times that of PHTG (prepared through hydrogen reduction followed by carbonization) and 1.56, 2.26, and 1.44 times that of DHTG (double hydrogen reduction). The high performance could be attributed to its fine particle size and rich N content, and the specific regulation mechanism was also proposed in this paper. This study opens a practical guide for effectively avoiding particle agglomeration during the fabrication process for catalysts. Full article

(This article belongs to the Topic Direct Interspecies Electron Transfer (DIET) Mediated by Electrically Conductive Materials)

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10 pages, 1914 KiB  

Open AccessArticle

Stimulation of Biomethane Productivity in Anaerobic Digestion Using Electro-Conductive Carbon-Nanotube Hollow-Fiber Media

by Seongmin Yang, Seungyeob Han, Yeo-Myeong Yun and Seoktae Kang

Minerals 2021, 11(2), 179; https://doi.org/10.3390/min11020179 - 8 Feb 2021

Cited by 9 | Viewed by 3508

Abstract

The production of biogas was promoted via direct interspecies electron transfer (DIET) by employing electro-conductive carbon-nanotube hollow-fiber media (CHM) in anaerobic digestion. Experimental results showed a positive effect of CHM presence on CH₄ productivity with 34% higher CH₄ production rate than [...] Read more.

The production of biogas was promoted via direct interspecies electron transfer (DIET) by employing electro-conductive carbon-nanotube hollow-fiber media (CHM) in anaerobic digestion. Experimental results showed a positive effect of CHM presence on CH₄ productivity with 34% higher CH₄ production rate than that of in the presence of non-electroconductive polymeric hollow fiber media. An increased CH₄ production rate was due to the shift in the microbiome with more abundant Pelobacter (10.0%), Geobacter (6.9%), and Methanosaeta (15.7%), which play key roles in promoting CH₄ production via syntrophic metabolism associated with DIET. Microscopic morphology analysis, using confocal laser scanning microscopy and scanning electron microscopy, exhibited that several living cells were attached with electro-conductive pili on the CHM surface, thereby facilitated electron transport between microbial cells. Full article

(This article belongs to the Topic Direct Interspecies Electron Transfer (DIET) Mediated by Electrically Conductive Materials)

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