Microbial Electrosynthesis: Feeding Microbes Electricity To Convert Carbon Dioxide and Water to Multicarbon Extracellular Organic Compounds

Department of Microbiology, University of Massachusetts, Amherst, Massachusetts, USA.
mBio (Impact Factor: 6.79). 06/2010; 1(2). DOI: 10.1128/mBio.00103-10
Source: PubMed


Reducing carbon dioxide to multicarbon organic chemicals and fuels with electricity has been identified as an attractive strategy to convert solar energy that is harvested intermittently with photovoltaic technology and store it as covalent chemical bonds. The organic compounds produced can then be distributed via existing infrastructure. Nonbiological electrochemical reduction of carbon dioxide has proven problematic. The results presented here suggest that microbiological catalysts may be a robust alternative, and when coupled with photovoltaics, current-driven microbial carbon dioxide reduction represents a new form of photosynthesis that might convert solar energy to organic products more effectively than traditional biomass-based strategies.

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    • "The reactors were connected to a multi-potentiostat (CHI1040, Chenhua Co., Ltd., Shanghai, China) with cathodic potentials poised at − 500, −300, −100, and +250 mV, respectively. These potentials are higher than −600 mV, which avoids the production of H 2 in the system [16]. "
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    ABSTRACT: In this work, we reported that Thiobacillus denitrificans could utilize poised electrodes directly as sole electron donors for autotrophic denitrification in bioelectrochemical systems. A potential-dependent denitrification process was observed and catalyzed by the biofilms colonizing on the electrode surface, with a maximum nitrate removal rate of 21.12 ± 1.67 mmol NO3-- N L- 1 day- 1 m- 2 at a potential of - 500 mV. The intermediate products (nitrite and N2O) suggested that denitrification was the main electron transfer pathway, and dissimilatory nitrate reduction to ammonium was not present in this process. Cyclic voltammetry revealed the acclimation potentials played an important role in the electrochemical activity of the biofilms. Electron transport inhibitors suggested the participation of complex I, II, and III in the electron transfer during the denitrification.
    Electrochemistry Communications 11/2015; 60:126-130. DOI:10.1016/j.elecom.2015.08.025 · 4.85 Impact Factor
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    • "Initially the term microbial electrosynthesis was used exclusively for the microbial reduction of carbon dioxide with the help of electricity (Nevin et al., 2010; Rabaey and Rozendal, 2010). But the research field was quickly widened by multiple studies that follow the same approach of optimizing microbial production by electrical enhancement from other substrates than CO 2 , often referred to as electro fermentation (Kim and Kim, 1988; Emde and Schink, 1990; Shin et al., 2002; Steinbusch et al., 2009; Rabaey and Rozendal, 2010; Choi et al., 2012). "
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    ABSTRACT: Microbial electrochemical techniques describe a variety of emerging technologies that use electrode-bacteria-interactions for biotechnology applications including the production of electricity, waste and wastewater treatment, bioremediation and production of valuable products. Central in each application is the ability of the microbial catalyst to interact with external electron acceptors and/or donors and its metabolic properties that enable the combination of electron transport and carbon metabolism. And here also lies the key challenge. A wide range of microbes has been discovered to be able to exchange electrons with solid surfaces or mediators but only a few have been studied in depth. Especially electron transfer mechanisms from cathodes towards the microbial organism are poorly understood but are essential for many applications such as microbial electrosynthesis. We analyse the different electron transport chains that nature offers for organisms such as metal respiring bacteria and acetogens, but also standard biotechnological organisms currently used in bio-production. Special focus lies on the essential connection of redox and energy metabolism, which is often ignored when studying bio-electrochemical systems. The possibility of extracellular electron exchange at different points in each organism is discussed regarding required redox potentials and effect on cellular redox and energy levels. Key compounds such as electron carriers (e.g. cytochromes, ferredoxin, quinones, flavins) are identified and analysed regarding their possible role in electrode-microbe-interactions. This work summarizes our current knowledge on electron transport processes and uses a theoretical approach to predict the impact of different modes of transfer on the energy metabolism. As such it adds an important piece of fundamental understanding of microbial electron transport possibilities to the research community and will help to optimize and advance bio-electrochemical techniques.
    Frontiers in Microbiology 05/2015; 6. DOI:10.3389/fmicb.2015.00575 · 3.99 Impact Factor
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    • "n previous studies with Geobacter species ( Gregory et al . , 2004 ) and inferred in previ - ous studies of microbial electrosynthesis with acetogenic bacteria ( Nevin et al . , 2010 , 2011 ) . However , the recovery of electrons consumed in acetate produced with the DC power source systems ( Table 2 ) was comparable with the previously reported ( Nevin et al . , 2010 ) recovery of 86 ± 21% in the potentiostat - poised system with more positive cathode potentials . Therefore , even if H 2 was the ultimate electron donor for electrosynthesis in the DC power source systems , this was of little practical conse - quence as the S . ovata biofilms were highly effective in scavenging H 2 before it was lost "
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    ABSTRACT: Microbial electrosynthesis, an artificial form of photosynthesis, can efficiently convert carbon dioxide into organic commodities; however, this process has only previously been demonstrated in reactors that have features likely to be a barrier to scale-up. Therefore, the possibility of simplifying reactor design by both eliminating potentiostatic control of the cathode and removing the membrane separating the anode and cathode was investigated with biofilms of Sporomusa ovata. S. ovata reduces carbon dioxide to acetate and acts as the microbial catalyst for plain graphite stick cathodes as the electron donor. In traditional 'H-cell' reactors, where the anode and cathode chambers were separated with a proton-selective membrane, the rates and columbic efficiencies of microbial electrosynthesis remained high when electron delivery at the cathode was powered with a direct current power source rather than with a potentiostat-poised cathode utilized in previous studies. A membrane-less reactor with a direct-current power source with the cathode and anode positioned to avoid oxygen exposure at the cathode, retained high rates of acetate production as well as high columbic and energetic efficiencies. The finding that microbial electrosynthesis is feasible without a membrane separating the anode from the cathode, coupled with a direct current power source supplying the energy for electron delivery, is expected to greatly simplify future reactor design and lower construction costs.
    Frontiers in Microbiology 05/2015; 6:468. DOI:10.3389/fmicb.2015.00468 · 3.99 Impact Factor
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