Set anode potentials affect the electron fluxes and microbial community structure in propionate-fed microbial electrolysis cells

Hari, Ananda Rao; Katuri, Krishna P.; Logan, Bruce E.; Saikaly, Pascal E.

doi:10.1038/srep38690

Cited by 55 publications

(26 citation statements)

References 49 publications

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“…showing that a direct electrooxidation of proprionate is possible. On the other hand, Hari et al (2016) suggested that current from propionate would be generated via acetate.…”

Section: Concentration Pulse Responses Under Closed Circuit Potentiosmentioning

confidence: 99%

Concentration Pulse Method for the Investigation of Transformation Pathways in a Glycerol-Fed Bioelectrochemical System

et al. 2018

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We investigated transformation pathways and determined rate constants in a continuously operated glycerol-fed bioelectrochemical system under chemostatic conditions by applying concentration pulses of various intermediates. Our methodology does not require the interruption of the continuous operation and is thus in principle suitable for elucidating processes in continuously operated bioreactors in industry as well as in laboratory studies. Specifically for the example of glycerol electrooxidation, pulse responses of current density and effluent concentrations reveal that glycerol is first fermented to acetate, which is then oxidized electrochemically by the anode respiring bacteria. Microbial community analysis confirms this division of labor with a bioanode dominated by Geobacter species (92.8%) and a much more diverse fermenting community in the planktonic phase, containing mainly Desulfovibrio sp. (45.2%) and Spiroaetales (18.1%). Desulfovibrio and Geobacter species are identified as promising candidates for tailored communities for glycerol electro-oxidation. From an acetate concentration pulse experiment, growth rates and half saturation rate constants for the biofilm of 1.4 mol m −3 and 933 mmol m −2 d −2 are obtained, respectively. Furthermore, 1,3-propanediol and glycerol concentration pulse experiments show that the reaction from glycerol to 1,3-propanediol is reversed at high 1,3-propanediol concentrations. The presented methodology allows one to study pathways and extract rate constants through simple experiments in a running system without irreversibly altering the microbial community or destroying the biofilm.

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“…showing that a direct electrooxidation of proprionate is possible. On the other hand, Hari et al (2016) suggested that current from propionate would be generated via acetate.…”

Section: Concentration Pulse Responses Under Closed Circuit Potentiosmentioning

confidence: 99%

Concentration Pulse Method for the Investigation of Transformation Pathways in a Glycerol-Fed Bioelectrochemical System

et al. 2018

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“…Thus, they were observed to potentially play both roles in the community. The exoelectrogens-fermenter synergy results from cross-feeding of intermediates (Zeng et al, 2017;Lewis et al, 2018), which has been reported by other groups illustrating the syntrophy in bioanode fed with other fermentable substrates as well (Freguia et al, 2007;Parameswaran et al, 2009;Kiely et al, 2011;Hari et al, 2016b). Use of a complex substrate such as BOAP in a bioanode results in a complex web of microbial interactions as shown in Figure 5.…”

Section: Bioelectrochemistry Of Primary Reactions Leading To Electroamentioning

confidence: 55%

Efficient Conversion of Aqueous-Waste-Carbon Compounds Into Electrons, Hydrogen, and Chemicals via Separations and Microbial Electrocatalysis

et al. 2018

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Valorization of waste streams is becoming increasingly important to improve resource recovery and economics of bioprocesses for the production of fuels. The pyrolysis process produces a significant portion of the biomass as an aqueous waste stream, called bio-oil aqueous phase (BOAP), which cannot be effectively converted into fuel. In this report, we detail the separation and utilization of this stream for the production of electrons, hydrogen, and chemicals, which can supplement fuel production improving economics of the biorefinery. Separation methods including physical separation via centrifugal separator, chemical separation via pH manipulation, and electrochemical separation via capacitive deionization are discussed. Bioelectrochemical systems (BES) including microbial fuel cells (MFCs), microbial electrolysis cells (MECs), and electrofermentation processes are reviewed for their potential to generate current, hydrogen, and chemicals from BOAP. Recent developments in MECs using complex waste streams and electro-active biocatalyst enrichment have resulted in advancement of the technology toward performance metrics closer to commercial requirements. Current densities above 10 A/m 2 have been reported using BOAP, which suggest further work to demonstrate the technology at pilot scale should be undertaken. The research on electro-fermentation is revealing potential to generate alcohols, diols, medium chain fatty acids, esters, etc. using electrode-based electrons. The ability to derive electrons and chemical building blocks from waste streams illustrate the advancement of the BES technology and potential to push the frontiers of bioenergy generation one step further toward development of a circular bioeconomy.

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“…Amplicon libraries were prepared for the archaeal and bacterial 16S rRNA gene V3–V4 region using up to 10 ng of the extracted DNA, the forward primer Pro341F (5′-CCTACGGGNBGCASCAG-3′) and the reverse primer Pro805R (5′-GACTACNVGGGTATCTAATCC-3′) (Hari et al, 2016). Each PCR reaction (25 μL) contained dNTPs (100 μM of each), MgSO 4 (1.5 mM), Platinum Taq DNA polymerase HF (0.5 U/reaction), Platinum High Fidelity buffer (1x) (Thermo Fisher Scientific, United States) and tailed primer mix (400 nM of each forward and reverse primer).…”

Section: Methodsmentioning

confidence: 99%

Evidence of Spatial Homogeneity in an Electromethanogenic Cathodic Microbial Community

et al. 2019

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Microbial electrosynthesis (MES) has been gaining considerable interest as the next step in the evolution of microbial electrochemical technologies. Understanding the niche biocathode environment and microbial community is critical for further developing this technology as the biocathode is key to product formation and efficiency. MES is generally operated to enrich a specific functional group (e.g., methanogens or homoacetogens) from a mixed-culture inoculum. However, due to differences in H 2 and CO 2 availability across the cathode surface, competition and syntrophy may lead to overall variability and significant beta-diversity within and between replicate reactors, which can affect performance reproducibility. Therefore, this study aimed to investigate the distribution and potential spatial variability of the microbial communities in MES methanogenic biocathodes. Triplicate methanogenic biocathodes were enriched in microbial electrolysis cells for 5 months at an applied voltage of 0.7 V. They were then transferred to triplicate dual-chambered MES reactors and operated at -1.0 V vs. Ag/AgCl for six batches. At the end of the experiment, triplicate samples were taken at different positions (top, center, bottom) from each biocathode for a total of nine samples for total biomass protein analysis and 16S rRNA gene amplicon sequencing. Microbial community analyses showed that the biocathodes were highly enriched with methanogens, especially the hydrogenotrophic methanogen family Methanobacteriaceae, Methanobacterium sp., and the mixotrophic Methanosarcina sp., with an overall core community representing > 97% of sequence reads in all samples. There was no statistically significant spatial variability ( p > 0.05) observed in the distribution of these communities within and between the reactors. These results suggest deterministic community assembly and indicate the reproducibility of electromethanogenic biocathode communities, with implications for larger-scale reactors.

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Set anode potentials affect the electron fluxes and microbial community structure in propionate-fed microbial electrolysis cells

Cited by 55 publications

References 49 publications

Concentration Pulse Method for the Investigation of Transformation Pathways in a Glycerol-Fed Bioelectrochemical System

Concentration Pulse Method for the Investigation of Transformation Pathways in a Glycerol-Fed Bioelectrochemical System

Efficient Conversion of Aqueous-Waste-Carbon Compounds Into Electrons, Hydrogen, and Chemicals via Separations and Microbial Electrocatalysis

Evidence of Spatial Homogeneity in an Electromethanogenic Cathodic Microbial Community

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