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Open accessJournal ArticleDOI: 10.1073/PNAS.2020552118

Acetogenic bacteria utilize light-driven electrons as an energy source for autotrophic growth.

02 Mar 2021-Proceedings of the National Academy of Sciences of the United States of America (National Academy of Sciences)-Vol. 118, Iss: 9
Abstract: Acetogenic bacteria use cellular redox energy to convert CO2 to acetate using the Wood-Ljungdahl (WL) pathway. Such redox energy can be derived from electrons generated from H2 as well as from inorganic materials, such as photoresponsive semiconductors. We have developed a nanoparticle-microbe hybrid system in which chemically synthesized cadmium sulfide nanoparticles (CdS-NPs) are displayed on the cell surface of the industrial acetogen Clostridium autoethanogenum The hybrid system converts CO2 into acetate without the need for additional energy sources, such as H2, and uses only light-induced electrons from CdS-NPs. To elucidate the underlying mechanism by which C. autoethanogenum uses electrons generated from external energy sources to reduce CO2, we performed transcriptional analysis. Our results indicate that genes encoding the metal ion or flavin-binding proteins were highly up-regulated under CdS-driven autotrophic conditions along with the activation of genes associated with the WL pathway and energy conservation system. Furthermore, the addition of these cofactors increased the CO2 fixation rate under light-exposure conditions. Our results demonstrate the potential to improve the efficiency of artificial photosynthesis systems based on acetogenic bacteria integrated with photoresponsive nanoparticles.

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Topics: Energy source (58%), Clostridium autoethanogenum (56%), Acetogen (52%)

7 results found

Journal ArticleDOI: 10.1016/J.CEJ.2021.131325
Jiyun Bae1, Yoseb Song1, Hyeonsik Lee1, Jongoh Shin1  +3 moreInstitutions (1)
Abstract: In times of global warming and upcoming fossil fuel shortages, the demand for the replacement of current fossil fuel-based chemical production via the development of alternative technologies and sustainable resources has increased. As a possible solution, an approach that produces chemicals from C1 gases derived from industrial waste gas or syngas has been suggested, but inefficient costs and syngas contaminant-sensitive processes of chemical catalysts have limited C1 gas utilization. Recently, acetogenic bacteria have received much attention as potential biocatalysts capable of C1 gas valorization into value-added chemicals. A comprehensive overview of C1 gas conversion using acetogenic bacteria as biocatalysts and a wide range of value-added products converted from C1 gases is provided in this review. Additionally, several strategies for enhancing product yield and alcohol selectivity during the gas fermentation processes, converting native products into valuable longer carbon compounds through coupling gas fermentation with additional processes, and overcoming energetic limitations underlying acetogenic bacteria via strain engineering are discussed.

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Topics: Syngas (51%)

6 Citations

Open accessJournal ArticleDOI: 10.1111/1751-7915.13911
Kyeong Rok Choi1, Hye Eun Yu1, Sang Yup Lee1Institutions (1)
Abstract: Sustainable food production is a key to solve complicated and intertwined issues of overpopulation, climate change, environment and sustainability. Microorganisms, which have been routinely consumed as a part of fermented foods and more recently as probiotic dietary supplements, can be repurposed for our food to present a sustainable solution to current food production system. This paper begins with three snapshots of our future life with microbial foods. Next, the importance, possible forms, and raw materials (i.e. microorganisms and their carbon and energy sources) of microbial foods are discussed. In addition, the production strategies, further applications and current limitations of microbial foods are discussed.

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Topics: Food processing (56%), Energy source (51%)

1 Citations

Open accessJournal ArticleDOI: 10.3390/FERMENTATION7040291
30 Nov 2021-Fermentation
Abstract: Microbial electrocatalysis reckons on microbes as catalysts for reactions occurring at electrodes. Microbial fuel cells and microbial electrolysis cells are well-known in this context; both prefer the oxidation of organic and inorganic matter for producing electricity. Notably, the synthesis of high energy-density chemicals (fuels) or their precursors by microorganisms using bio-cathode to yield electrical energy is called Microbial Electrosynthesis (MES), giving an exceptionally appealing novel way for producing beneficial products from electricity and wastewater. This review accentuates the concept, importance and opportunities of MES, as an emerging discipline at the nexus of microbiology and electrochemistry. Production of organic compounds from MES is considered as an effective technique for the generation of various beneficial reduced end-products (like acetate and butyrate) as well as in reducing the load of CO2 from the atmosphere to mitigate the harmful effect of greenhouse gases in global warming. Although MES is still an emerging technology, this method is not thoroughly known. The authors have focused on MES, as it is the next transformative, viable alternative technology to decrease the repercussions of surplus carbon dioxide in the environment along with conserving energy.

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Open accessJournal ArticleDOI: 10.1016/J.ISCI.2021.102952
05 Aug 2021-iScience
Abstract: The conversion of CO2 to value-added products powered with solar energy is an ideal solution to establishing a closed carbon cycle. Combining microorganisms with light-harvesting nanomaterials into photosynthetic biohybrid systems (PBSs) presents an approach to reaching this solution. Metabolic pathways precisely evolved for CO2 fixation selectively and reliably generate products. Nanomaterials harvest solar light and biocompatibly associate with microorganisms owing to similar lengths scales. Although this is a nascent field, a variety of approaches have been implemented encompassing different microorganisms and nanomaterials. To advance the field in an impactful manner, it is paramount to understand the molecular underpinnings of PBSs. In this perspective, we highlight studies inspecting charge uptake pathways and singularities in photosensitized cells. We discuss further analyses to more completely elucidate these constructs, and we focus on criteria to be met for designing photosensitizing nanomaterials. As a result, we advocate for the pairing of microorganisms with naturally occurring and highly biocompatible mineral-based semiconductor nanomaterials.

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Open accessJournal ArticleDOI: 10.1186/S40643-021-00470-7
Qiang Ding1, Yadi Liu1, Guipeng Hu1, Liang Guo1  +5 moreInstitutions (1)
Abstract: Microbial organelles are a promising model to promote cellular functions for the production of high-value chemicals. However, the concentrations of enzymes and nanoparticles are limited by the contact surface in single Escherichia coli cells. Herein, the definition of contact surface is to improve the amylase and CdS nanoparticles concentration for enhancing the substrate starch and cofactor NADH utilization. In this study, two biofilm-based strategies were developed to improve the contact surface for the production of shikimate and L-malate. First, the contact surface of E. coli was improved by amylase self-assembly with a blue light-inducible biofilm-based SpyTag/SpyCatcher system. This system increased the glucose concentration by 20.7% and the starch-based shikimate titer to 50.96 g L−1, which showed the highest titer with starch as substrate. Then, the contact surface of E. coli was improved using a biofilm-based CdS-biohybrid system by light-driven system, which improved the NADH concentration by 83.3% and increased the NADH-dependent L-malate titer to 45.93 g L−1. Thus, the biofilm-based strategies can regulate cellular functions to increase the efficiency of microbial cell factories based on the optogenetics, light-driven, and metabolic engineering.

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Topics: Biofilm (56%), Amylase (52%)


38 results found

Open accessJournal ArticleDOI: 10.1186/S13059-014-0550-8
05 Dec 2014-Genome Biology
Abstract: In comparative high-throughput sequencing assays, a fundamental task is the analysis of count data, such as read counts per gene in RNA-seq, for evidence of systematic changes across experimental conditions. Small replicate numbers, discreteness, large dynamic range and the presence of outliers require a suitable statistical approach. We present DESeq2, a method for differential analysis of count data, using shrinkage estimation for dispersions and fold changes to improve stability and interpretability of estimates. This enables a more quantitative analysis focused on the strength rather than the mere presence of differential expression. The DESeq2 package is available at .

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Topics: MRNA Sequencing (54%), Integrator complex (51%), Count data (50%) ... read more

29,675 Citations

Open accessJournal ArticleDOI: 10.1073/PNAS.0710525105
Abstract: Bacteria able to transfer electrons to metals are key agents in biogeochemical metal cycling, subsurface bioremediation, and corrosion processes. More recently, these bacteria have gained attention as the transfer of electrons from the cell surface to conductive materials can be used in multiple applications. In this work, we adapted electrochemical techniques to probe intact biofilms of Shewanella oneidensis MR-1 and Shewanella sp. MR-4 grown by using a poised electrode as an electron acceptor. This approach detected redox-active molecules within biofilms, which were involved in electron transfer to the electrode. A combination of methods identified a mixture of riboflavin and riboflavin-5′-phosphate in supernatants from biofilm reactors, with riboflavin representing the dominant component during sustained incubations (>72 h). Removal of riboflavin from biofilms reduced the rate of electron transfer to electrodes by >70%, consistent with a role as a soluble redox shuttle carrying electrons from the cell surface to external acceptors. Differential pulse voltammetry and cyclic voltammetry revealed a layer of flavins adsorbed to electrodes, even after soluble components were removed, especially in older biofilms. Riboflavin adsorbed quickly to other surfaces of geochemical interest, such as Fe(III) and Mn(IV) oxy(hydr)oxides. This in situ demonstration of flavin production, and sequestration at surfaces, requires the paradigm of soluble redox shuttles in geochemistry to be adjusted to include binding and modification of surfaces. Moreover, the known ability of isoalloxazine rings to act as metal chelators, along with their electron shuttling capacity, suggests that extracellular respiration of minerals by Shewanella is more complex than originally conceived.

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Topics: Shewanella oneidensis (62%), Shewanella (58%), Exoelectrogen (55%) ... read more

1,438 Citations

Journal ArticleDOI: 10.1038/NRMICRO2422
Korneel Rabaey1, René A. Rozendal1Institutions (1)
Abstract: Microbial electrocatalysis relies on microorganisms as catalysts for reactions occurring at electrodes. Microbial fuel cells and microbial electrolysis cells are well known in this context; both use microorganisms to oxidize organic or inorganic matter at an anode to generate electrical power or H(2), respectively. The discovery that electrical current can also drive microbial metabolism has recently lead to a plethora of other applications in bioremediation and in the production of fuels and chemicals. Notably, the microbial production of chemicals, called microbial electrosynthesis, provides a highly attractive, novel route for the generation of valuable products from electricity or even wastewater. This Review addresses the principles, challenges and opportunities of microbial electrosynthesis, an exciting new discipline at the nexus of microbiology and electrochemistry.

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Topics: Microbial electrosynthesis (76%), Bioelectrochemical reactor (62%), Electromethanogenesis (56%) ... read more

1,111 Citations

Open accessJournal ArticleDOI: 10.1128/MBIO.00103-10
29 Jun 2010-Mbio
Abstract: The possibility of providing the acetogenic microorganism Sporomusa ovata with electrons delivered directly to the cells with a graphite electrode for the reduction of carbon dioxide to organic compounds was investigated. Biofilms of S. ovata growing on graphite cathode surfaces consumed electrons with the reduction of carbon dioxide to acetate and small amounts of 2-oxobutyrate. Electrons appearing in these products accounted for over 85% of the electrons consumed. These results demonstrate that microbial production of multicarbon organic compounds from carbon dioxide and water with electricity as the energy source is feasible.

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737 Citations

Journal ArticleDOI: 10.1038/NRMICRO.2016.93
Liang Shi1, Hailiang Dong2, Gemma Reguera3, Haluk Beyenal4  +4 moreInstitutions (7)
Abstract: Electrons can be transferred from microorganisms to multivalent metal ions that are associated with minerals and vice versa. As the microbial cell envelope is neither physically permeable to minerals nor electrically conductive, microorganisms have evolved strategies to exchange electrons with extracellular minerals. In this Review, we discuss the molecular mechanisms that underlie the ability of microorganisms to exchange electrons, such as c-type cytochromes and microbial nanowires, with extracellular minerals and with microorganisms of the same or different species. Microorganisms that have extracellular electron transfer capability can be used for biotechnological applications, including bioremediation, biomining and the production of biofuels and nanomaterials.

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Topics: Biomining (60%)

693 Citations

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