Electrochemistry of R. palustris Azul during phototrophic growth
TL;DR: Electrochemical characterization of an autochthonous R. palustris AZUL is reported, which indicates that this strain has a mechanism of redox balance that includes charge storage in redox molecules that can transfer charge to the extracellular space when a high potential acceptor is available.
About: This article is published in Electrochimica Acta.The article was published on 2020-09-20. It has received 6 citations till now. The article focuses on the topics: Rhodopseudomonas palustris & Electron acceptor.
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01 Jan 2016
TL;DR: In this article, a continuous flow synthesis (CFS) method is proposed for the efficient, effective and reproducible synthesis of inorganic compounds, and the effect of synthesis route on particle size, size distribution, and crystallinity is compared.
Abstract: Advanced materials are essential to the quality of modern day life, but the synthesis of these compounds is often inefficient in terms of energy, time and resources; especially when considering the hydrothermal batch methods used to prepare many such compounds – often requiring week-long reaction times with variable yields and product quality. In contrast, Continuous flow synthesis (CFS) provides a more readily scalable means for the efficient, effective and reproducible synthesis of inorganic compounds. This publication demonstrates the novel CFS of several metal ammonium phosphates and compare the effect of synthesis route on particle size, size distribution, and crystallinity.
271 citations
TL;DR: Rhodopseudomonas palustris is an attractive option for biotechnical applications and industrial engineering due to its metabolic versatility and its ability to catabolize a wide variety of feedstocks and convert them to several high-value products as mentioned in this paper .
18 citations
TL;DR: In this paper , a fluid-like electrode can accept electrons from the metabolism of planktonically grown phototrophic bacteria (PPB), which can contribute to the sustainability of an electrobioremediation wastewater treatment by avoiding emissions of greenhouse gases such as methane.
2 citations
TL;DR: In this article , a rod-like graphite carbon nitride-molybdenum disulfide (RCM) of S-scheme was prepared by hydrothermal method and loaded onto the exterior surface of chitosan modified polyurethane sponge (CPU).
TL;DR: In this paper , a photo microbial electrochemical fluidized-bed reactor (photoME-FBR) was operated with low-reduced (3.5 e−/C) and high reduced (5.9 e− /C) wastewater under cathodic polarization (−0.4
Abstract: The climate crisis requires rethinking wastewater treatment to recover resources, such as nutrients and energy. In this scenario, purple phototrophic bacteria (PPB), the most versatile microorganisms on earth, are a promising alternative to transform the wastewater treatment plant concept into a biorefinery model by producing valuable protein-enriched biomass. PPB are capable of interacting with electrodes, exchanging electrons with electrically conductive materials. In this work, we have explored for mobile-bed (either stirred or fluidized) cathodes to maximize biomass production. For this purpose, stirred-electrode reactors were operated with low-reduced (3.5 e−/C) and high-reduced (5.9 e−/C) wastewater under cathodic polarization (−0.4 V and –0.8 V vs. Ag/AgCl). We observed that cathodic polarization and IR irradiation can play a key role in microbial and phenotypic selection, promoting (at –0.4 V) or minimizing (at –0.8 V) the presence of PPB. Then, we further study how cathodic polarization modulates PPB biomass production providing a fluid-like electrode as part of a so-called photo microbial electrochemical fluidized-bed reactor (photoME-FBR). Our results revealed the impact of reduction status of carbon source in wastewater to select the PPB photoheterotrophic community and how electrodes drive microbial population shifts depending on the reduction status of such carbon source.
References
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TL;DR: 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.
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.
1,582 citations
TL;DR: A new form of microbial respiration has recently been discovered in which microorganisms conserve energy to support growth by oxidizing organic compounds to carbon dioxide with direct quantitative electron transfer to electrodes.
Abstract: It is well established that some reduced fermentation products or microbially reduced artificial mediators can abiotically react with electrodes to yield a small electrical current. This type of metabolism does not typically result in an efficient conversion of organic compounds to electricity because only some metabolic end products will react with electrodes, and the microorganisms only incompletely oxidize their organic fuels. A new form of microbial respiration has recently been discovered in which microorganisms conserve energy to support growth by oxidizing organic compounds to carbon dioxide with direct quantitative electron transfer to electrodes. These organisms, termed electricigens, offer the possibility of efficiently converting organic compounds into electricity in self-sustaining systems with long-term stability.
1,172 citations
TL;DR: Results show that electromethanogenesis can be used to convert electrical current produced from renewable energy sources (such as wind, solar, or biomass) into a biofuel (methane) as well as serving as a method for the capture of carbon dioxide.
Abstract: New sustainable methods are needed to produce renewable energy carriers that can be stored and used for transportation, heating, or chemical production. Here we demonstrate that methane can directly be produced using a biocathode containing methanogens in electrochemical systems (abiotic anode) or microbial electrolysis cells (MECs; biotic anode) by a process called electromethanogenesis. At a set potential of less than −0.7 V (vs Ag/AgCl), carbon dioxide was reduced to methane using a two-chamber electrochemical reactor containing an abiotic anode, a biocathode, and no precious metal catalysts. At −1.0 V, the current capture efficiency was 96%. Electrochemical measurements made using linear sweep voltammetry showed that the biocathode substantially increased current densities compared to a plain carbon cathode where only small amounts of hydrogen gas could be produced. Both increased current densities and very small hydrogen production rates by a plain cathode therefore support a mechanism of methane pro...
1,015 citations
TL;DR: The genome sequence of R. palustris is described, which reveals genes that confer a remarkably large number of options within a given type of metabolism, including three nitrogenases, five benzene ring cleavage pathways and four light harvesting 2 systems.
Abstract: Rhodopseudomonas palustris is among the most metabolically versatile bacteria known. It uses light, inorganic compounds, or organic compounds, for energy. It acquires carbon from many types of green plant-derived compounds or by carbon dioxide fixation, and it fixes nitrogen. Here we describe the genome sequence of R. palustris, which consists of a 5,459,213-base-pair (bp) circular chromosome with 4,836 predicted genes and a plasmid of 8,427 bp. The sequence reveals genes that confer a remarkably large number of options within a given type of metabolism, including three nitrogenases, five benzene ring cleavage pathways and four light harvesting 2 systems. R. palustris encodes 63 signal transduction histidine kinases and 79 response regulator receiver domains. Almost 15% of the genome is devoted to transport. This genome sequence is a starting point to use R. palustris as a model to explore how organisms integrate metabolic modules in response to environmental perturbations.
704 citations
TL;DR: The detection of arsenate and selenate respiring bacteria in numerous pristine and contaminated environments and their rapid appearance in enrichment culture suggest that they are widespread and metabolically active in nature.
Abstract: Oxyanions of arsenic and selenium can be used in microbial anaerobic respiration as terminal electron acceptors. The detection of arsenate and selenate respiring bacteria in numerous pristine and contaminated environments and their rapid appearance in enrichment culture suggest that they are widespread and metabolically active in nature. Although the bacterial species that have been isolated and characterized are still few in number, they are scattered throughout the bacterial domain and include Gram-positive bacteria, beta, gamma and epsilon Proteobacteria and the sole member of a deeply branching lineage of the bacteria, Chrysiogenes arsenatus. The oxidation of a number of organic substrates (i.e. acetate, lactate, pyruvate, glycerol, ethanol) or hydrogen can be coupled to the reduction of arsenate and selenate, but the actual donor used varies from species to species. Both periplasmic and membrane-associated arsenate and selenate reductases have been characterized. Although the number of subunits and molecular masses differs, they all contain molybdenum. The extent of the environmental impact on the transformation and mobilization of arsenic and selenium by microbial dissimilatory processes is only now being fully appreciated.
565 citations