Electrifying microbes for the production of chemicals

Tremblay, Pier-Luc; Zhang, Tian

doi:10.3389/fmicb.2015.00201

Cited by 153 publications

(124 citation statements)

References 89 publications

(152 reference statements)

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“…To manipulate (and optimize) these systems it is valuable to understand the metabolic pathways and extracellular electron transfer (EET) enzymes or molecules involved in cathode oxidation, and we must determine how these cathodic electron transport components are coupled to energy conservation by the microbial cell. While an increasingly robust body of literature has been established relating to microbial communities metabolizing with an anodic electron acceptor [6][7][8] , much is still unclear about the diverse metabolic capabilities of microorganisms and communities growing on a cathode 9 . The primary carbon fixing and hypothetical electron transport pathways associated with that microbial electrosynthesis system were described 10 , illustrating the value of the multi-omics approach to understand complex electrode-associated communities.…”

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confidence: 99%

Metabolic Reconstruction and Modeling Microbial Electrosynthesis

Marshall¹,

Ross²,

Weisenhorn³

et al. 2016

Preprint

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Microbial electrosynthesis is a renewable energy and chemical production platform that relies on microbial cells to capture electrons from a cathode and fix carbon. Yet despite the promise of this technology, the metabolic capacity of the microbes that inhabit the electrode surface and catalyze electron transfer in these systems remains largely unknown. We assembled thirteen draft genomes from a microbial electrosynthesis system producing primarily acetate from carbon dioxide, and their transcriptional activity was mapped to genomes from cells on the electrode surface and in the supernatant. This allowed us to create a metabolic model of the predominant community members belonging to Acetobacterium, Sulfurospirillum, and Desulfovibrio. According to the model, the Acetobacterium was the primary carbon fixer, and a keystone member of the community. Transcripts of soluble hydrogenases and ferredoxins from Acetobacterium and hydrogenases, formate dehydrogenase, and cytochromes of Desulfovibrio were found in high abundance near the electrode surface. Cytochrome c oxidases of facultative members of the community were highly expressed in the supernatant despite completely sealed reactors and constant flushing with anaerobic gases. These molecular discoveries and metabolic modeling now serve as a foundation for future examination and development of electrosynthetic microbial communities.A microbial electrosynthesis system (MES) is a bioelectrochemical device that employs microbes to generate, or synthesize, valuable products from CO 2 and electrons from the cathode 1 . This technology has potential for the renewable generation of biofuels and commodity chemicals, therefore understanding which microbes and which metabolic pathways are involved on biocathodes is critical to improving the performance of MESs. Furthermore, this work has broader environmental implications including understanding ecological aspects of one carbon metabolism and extracellular electron transfer relevant to global biogeochemical cycling.Advances in microbial electrosynthesis and related biocathode-driven processes have primarily focused on the production of three compounds: hydrogen 2 , methane 3 , and acetate 4 . However, microbial electrosynthesis can be used to generate value-added multi-carbon compounds such as alcohols and various short-chain fatty acids 5 . To manipulate (and optimize) these systems it is valuable to understand the metabolic pathways and extracellular electron transfer (EET) enzymes or molecules involved in cathode oxidation, and we must determine how these cathodic electron transport components are coupled to energy conservation by the microbial cell. While an increasingly robust body of literature has been established relating to microbial communities metabolizing with an anodic electron acceptor 6-8 , much is still unclear about the diverse metabolic capabilities of microorganisms and communities growing on a cathode 9 . Recently, a multi-omics evaluation of a mixed-species, carbon

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confidence: 99%

Metabolic Reconstruction and Modeling Microbial Electrosynthesis

Marshall¹,

Ross²,

Weisenhorn³

et al. 2016

Preprint

View full text Add to dashboard Cite

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“…Several researchers reported that microorganisms such as Acidithiobacillus ferrooxidans, Sporomusa ovata, Sporomusa silvacetica, Sporomusa sphaeroides, Clostridium aceticum, Clostridium ljungdahlii, Geobacter sulfurreducens, Moorella thermoacetica, Shewanella oneidensis, and Mariprofundus ferrooxydans attach to a cathode electrode and uptake electrons directly at potential ranging from «0 V to ¹0.6 V vs. Ag/AgCl via bacterial outer surface components such as c-type cytochromes. [53][54][55][56] Although little or no electrical current was observed at ¹0.2 V vs. Ag/AgCl in the streptomycetes (Fig. 2), they may attach via different mechanisms.…”

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confidence: 99%

Electrical Retrieval of Living Streptomycete Spores Using a Potential-Controlled ITO Electrode

et al. 2017

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The purpose of this study was to develop a novel electrical retrieval method for living spores of streptomycetes. Five strains of deep-sea Streptomyces sp. and typical strain Streptomyces albus suspended in 1/20 artificial seawater (1/20ASW) were selectively attached to an indium tin oxide/glass (ITO) working electrode region to which a −0.2 V vs. Ag/AgCl constant potential was applied for 24 h. Spores of all six streptomycetes produced either short fibrous or membranous materials and attached to the ITO electrode region. A +20 mV vs. Ag/AgCl, 12 MHz sine-wave potential was further applied for another 1 h to the deep-sea Streptomyces sp. ST.28 spores on the ITO electrode and colony-forming units increased 3.5 fold after 3 day cultivation compared with controls. The ST.28 spores almost completely lost the ability to adhere to the potential-applied ITO electrode when dispersed in Mg 2+ free 1/20ASW. We succeeded in the attachment and cultivation of specifically positioned single ST.28 spores on an ITO microelectrode surface with −0.2 V vs. Ag/AgCl potential application. A combination of micropatterning techniques for a living single streptomycete spore on the ITO electrode and omics technologies holds potential for new bioactive compound screening concepts and applications.

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“…MES remains a nascent concept with only few studies that have demonstrated the process in laboratory scale using either pure cultures [8][9][10][11] or mixed microbial consortia [12][13][14][15][16][17][18][19]73].…”

Section: Microbial Electrosynthesis From Co2 To Organics-a Reviewmentioning

confidence: 99%

“…Microbial electrosynthesis remains a nascent concept with only few studies that have demonstrated the process in laboratory scale using either pure cultures [8][9][10][11] or mixed microbial consortia [12][13][14][15][16][17][18][19]. Use of mixed microbial consortia is attractive as they can be readily generated in the required quantities, are more tolerant to environmental fluctuations [20] and thus far have showed higher MES production rates than pure cultures over long term operation [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Microbial electrosynthesis from carbon dioxide: performance enhancement and elucidation of mechanisms

Jourdin¹

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Microbial electrosynthesis (MES) of organics from carbon dioxide has been recently put forward as an attractive technology for the renewable production of valuable multi-carbon reduced end-products and as a promising CO 2 transformation strategy. MES is a biocathode-driven process that relies on the conversion of electrical energy into high energy-density chemicals. However, MES remains a nascent concept and there is still limited knowledge on many aspects.It is still unclear whether autotrophic microbial biocathode biofilms are able to selfregenerate under purely cathodic conditions without any external electron or organic carbon sources. Here we report on the successful development and long-term operation of an autotrophic biocathode whereby an electroactive biofilm was able to grow and sustain itself with CO 2 and the cathode as sole carbon and electron source, respectively, with H 2 as sole product. From a small inoculum of 15 mg COD (in 250 mL), the bioelectrochemical system operating at -0.5 V vs. SHE enabled an estimated biofilm growth of 300 mg as COD over a period of 276 days.A critical aspect is that reported performances of bioelectrosynthesis of organics are still insufficient for scaling MES to practical applications. Selective microbial consortia and biocathode material development are of paramount importance towards performance enhancement. A novel biocompatible, highly conductive three-dimensional cathode was manufactured by direct growth of flexible multiwalled carbon nanotubes on reticulated vitreous carbon (NanoWeb-RVC) by chemical vapour deposition (CVD). The results demonstrated that: (i) the high surface area to volume ratio of the macroporous RVC maximizes the available biofilm area while ensuring effective mass transfer to and from the biofilm, and (ii) the nanostructure enhances the bacteria-electrode interaction, biofilm development, microbial extracellular electron transfer, and acetate bioproduction rate.However, for scale-up beyond certain sizes, there are some limitations with the CVD technique. We harnessed the throwing power of electrophoretic deposition technique (EPD), suitable for industrial scale production, to form multi-walled CNT coatings onto RVC to generate a new hierarchical porous structure, hereafter called EPD-3D. A very effective mixed microbial consortium was successfully enriched and transferred to EPD-3D reactors and demonstrated drastic performance enhancement reaching biocathode current density of -102 ± 1 A m -2 and acetate production rate of 685 ± 30 g m -2 day -1 .ii An in-depth understanding on how electrons flow from the cathode to the terminal electron acceptor is still missing but crucial (e.g. for improved reactor design). High rates of acetate production by microbial electrosynthesis was shown to occur via biologically-induced hydrogen, likely through the biological synthesis of metal copper particles, with 99 ± 1% electron recovery into acetate. The acetate-producing bacteria showed the remarkable ability to consume a high H 2 flux (ca. 1.15 m ...

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Electrifying microbes for the production of chemicals

Cited by 153 publications

References 89 publications

Metabolic Reconstruction and Modeling Microbial Electrosynthesis

Metabolic Reconstruction and Modeling Microbial Electrosynthesis

Electrical Retrieval of Living Streptomycete Spores Using a Potential-Controlled ITO Electrode

Microbial electrosynthesis from carbon dioxide: performance enhancement and elucidation of mechanisms

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