Constraints on the Efficiency of Engineered Electromicrobial Production

Salimijazi, Farshid; Kim, Jaehwan; Schmitz, Alexa M.; Grenville, Richard; Bocarsly, Andrew Bruce; Barstow, Buz

doi:10.1016/j.joule.2020.08.010

Cited by 48 publications

(145 citation statements)

References 158 publications

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“…Their study also indicates that gas recycling to increase overall CO 2 utilization will be necessary when scaling-up these systems. Salimijazi et al (2020) also very recently developed a mathematical model to determine the maximum theoretical efficiency of MES processes from electrical power to biofuels. They predicted that by using highly engineered microorganisms, the conversion efficiency to biofuels could increase up to 52%.…”

Section: Introductionmentioning

confidence: 99%

A General Model for Biofilm-Driven Microbial Electrosynthesis of Carboxylates From CO2

2021

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Up to now, computational modeling of microbial electrosynthesis (MES) has been underexplored, but is necessary to achieve breakthrough understanding of the process-limiting steps. Here, a general framework for modeling microbial kinetics in a MES reactor is presented. A thermodynamic approach is used to link microbial metabolism to the electrochemical reduction of an intracellular mediator, allowing to predict cellular growth and current consumption. The model accounts for CO2 reduction to acetate, and further elongation to n-butyrate and n-caproate. Simulation results were compared with experimental data obtained from different sources and proved the model is able to successfully describe microbial kinetics (growth, chain elongation, and product inhibition) and reactor performance (current density, organics titer). The capacity of the model to simulate different system configurations is also shown. Model results suggest CO2 dissolved concentration might be limiting existing MES systems, and highlight the importance of the delivery method utilized to supply it. Simulation results also indicate that for biofilm-driven reactors, continuous mode significantly enhances microbial growth and might allow denser biofilms to be formed and higher current densities to be achieved.

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Section: Introductionmentioning

confidence: 99%

A General Model for Biofilm-Driven Microbial Electrosynthesis of Carboxylates From CO2

2021

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“…In this scenario, PMES system could be an attractive solution, which provides us an opportunity to drive green fuels from CO 2 at a competitive price. Recently, Salimijazi et al., nicely analyzed the engineering constraints of MES and provided the model-based solutions, reaching at least 50% electrical to biofuel conversion efficiency in PMES ( Salimijazi et al., 2020 ). However, this process needs substantial development before its application in real condition.…”

Section: Outlook and Future Prospectivementioning

confidence: 99%

An insight into the bioelectrochemical photoreduction of CO2 to value-added chemicals

et al. 2021

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Summary Goal of sustainable carbon neutral economy can be achieved by designing an efficient CO 2 reduction system to generate biofuels, in particular, by mimicking the mechanism of natural photosynthesis using semiconducting nanomaterials interfaced with electroactive bacteria (EAB) in a photosynthetic microbial electrosynthesis (PMES) system. This review paper presents an overview of the recent advancements in the biohybrid photoanode and photocathode materials. We discuss the reaction mechanism observed at photoanode and photocathode to enhance our understanding on the solar driven MES. We extend the discussion by showcasing the potential activity of EABs toward high selectivity and production rates for desirable products by manipulating their genomic sequence. Additionally, the critical challenges associated in scaling up the PMES system including the strategies for diminution of reactive oxygen species, low solubility of CO 2 in the typical electrolytes, low selectivity of product species are presented along with the suggestions of alternative strategies to achieve economically viable generation of (bio)commodities.

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“…Already, the Bionic Leaf device has demonstrated that technologies of this class could dramatically exceed the efficiency of photosynthesis 7,8 . However, while highly efficient at lab scale, the Bionic Leaf relies on H2-oxidation to transfer electrons from the electrode to microbes, and the low solubility of H2 in water would pose a significant challenge for scale-up of this and related technologies 9 .…”

Section: Introductionmentioning

confidence: 99%

“…Naturally occurring electroactive microbes can produce acetate and butyrate from CO2 and electricity with Faradaic efficiencies exceeding 90% 16 . Furthermore, theoretical analysis suggests that the upper limit efficiency of electromicrobial production of biofuels by EEU could rival that of H2-mediated systems 9 . However, naturally occurring electroactive organisms capable of EEU suffer from multiple technical drawbacks.…”

Section: Introductionmentioning

confidence: 99%

Identification of a Pathway for Electron Uptake in Shewanella oneidensis

Rowe

Salimijazi

Trutschel

et al. 2021

Preprint

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Extracellular electron transfer (EET) could enable electron uptake into microbial metabolism for the synthesis of complex, energy dense organic molecules from CO2 and renewable electricity1-6 . EET could do this with an efficiency comparable to H2 -oxidation7,8 but without the need for a volatile intermediate and the problems it causes for scale up9. However, naturally occurring electroactive organisms suffer from a number of technical drawbacks. Correcting these will require extensive knowledge of the genetics and mechanisms of electron uptake. To date, studies of electron uptake in electroactive microbes have focused on shared molecular machinery also used for anaerobic mineral reduction, like the Mtr EET complex in the electroactive microbe Shewanella oneidensis MR-110-14. However, this shared machinery cannot explain all features of electron uptake, hindering efforts to engineer electron uptake. To address this, we screened gene disruption mutants for 3,667 genes, representing ≈ 99% of all non-essential genes, from the S. oneidensis whole genome knockout collection using a redox dye oxidation assay as a proxy for electron uptake. Confirmation of electron uptake using electrochemical testing allowed us to identify five genes from S. oneidensis that are indispensable for electron uptake from a cathode. Knockout of each gene eliminates extracellular electron uptake, yet in 4 of the 5 cases produces no significant defect in electron donation to an anode, highlighting a distinct role for these loci in electron uptake vs. donation. This result highlights an electronic connection between aerobic and anaerobic electron transport chains that allow electrons from the reversible EET machinery to be coupled to different respiratory processes in S. oneidensis. Furthermore, we find homologs to these genes across many different genera suggesting that electron uptake by EET coupled to respiration could be a widespread phenomenon. These gene discoveries provide a foundation for studying this phenotype in exotic metal-oxidizing autotrophic microbes. Additionally, we anticipate that the characterization of these genes will allow for the genetic improvement of electron uptake in S. oneidensis; and genetically engineering electron uptake into a highly tractable host like E. coli to complement recent advances in synthetic CO2 fixation15.

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Constraints on the Efficiency of Engineered Electromicrobial Production

Cited by 48 publications

References 158 publications

A General Model for Biofilm-Driven Microbial Electrosynthesis of Carboxylates From CO2

A General Model for Biofilm-Driven Microbial Electrosynthesis of Carboxylates From CO2

An insight into the bioelectrochemical photoreduction of CO2 to value-added chemicals

Identification of a Pathway for Electron Uptake in Shewanella oneidensis

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