The Experts below are selected from a list of 981 Experts worldwide ranked by ideXlab platform
Souichiro Kato - One of the best experts on this subject based on the ideXlab platform.
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Enhancement of methanogenesis by electric Syntrophy with biogenic iron-sulfide minerals.
MicrobiologyOpen, 2018Co-Authors: Souichiro Kato, Kensuke IgarashiAbstract:Recent studies have shown that interspecies electron transfer between chemoheterotrophic bacteria and methanogenic archaea can be mediated by electric currents flowing through conductive iron oxides, a process termed electric Syntrophy. In this study, we conducted enrichment experiments with methanogenic microbial communities from rice paddy soil in the presence of ferrihydrite and/or sulfate to determine whether electric Syntrophy could be enabled by biogenic iron sulfides. Although supplementation with either ferrihydrite or sulfate alone suppressed methanogenesis, supplementation with both ferrihydrite and sulfate enhanced methanogenesis. In the presence of sulfate, ferrihydrite was transformed into black precipitates consisting mainly of poorly crystalline iron sulfides. Microbial community analysis revealed that a methanogenic archaeon and iron- and sulfate-reducing bacteria (Methanosarcina, Geobacter, and Desulfotomaculum, respectively) predominated in the enrichment culture supplemented with both ferrihydrite and sulfate. Addition of an inhibitor specific for methanogenic archaea decreased the abundance of Geobacter, but not Desulfotomaculum, indicating that Geobacter acquired energy via syntrophic interaction with methanogenic archaea. Although electron acceptor compounds such as sulfate and iron oxides have been thought to suppress methanogenesis, this study revealed that coexistence of sulfate and iron oxide can promote methanogenesis by biomineralization of (semi)conductive iron sulfides that enable methanogenesis via electric Syntrophy.
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Electrochemical biotechnologies minimizing the required electrode assemblies
Current Opinion in Biotechnology, 2018Co-Authors: Kengo Sasaki, Shuji Nakanishi, Kazuhide Kamiya, Daisuke Sasaki, Akihiko Kondo, Souichiro KatoAbstract:Microbial electrochemical systems (MESs) are expected to be put into practical use as an environmental technology that can support a future environmentally friendly society. However, conventional MESs present a challenge of inevitably increasing initial investment, mainly due to requirements for a large numbers of electrode assemblies. In this review, we introduce electrochemical biotechnologies that are under development and can minimize the required electrode assemblies. The novel biotechnologies, called electro-fermentation and indirect electro-stimulation, can drive specific microbial metabolism by electrochemically controlling intercellular and extracellular redox states, respectively. Other technologies, namely electric Syntrophy and microbial photo-electrosynthesis, obviate the need for electrode assemblies, instead stimulating targeted reactions by using conductive particles to create new metabolic electron flows.
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Conductive iron oxides accelerate thermophilic methanogenesis from acetate and propionate
Journal of Bioscience and Bioengineering, 2015Co-Authors: Chihaya Yamada, Souichiro Kato, Yoshiyuki Ueno, Masaharu Ishii, Yasuo IgarashiAbstract:Anaerobic digester is one of the attractive technologies for treatment of organic wastes and wastewater, while continuous development and improvements on their stable operation with efficient organic removal are required. Particles of conductive iron oxides (e.g., magnetite) are known to facilitate microbial interspecies electron transfer (termed as electric Syntrophy). Electric Syntrophy has been reported to enhance methanogenic degradation of organic acids by mesophilic communities in soil and anaerobic digester. Here we investigated the effects of supplementation of conductive iron oxides (magnetite) on thermophilic methanogenic microbial communities derived from a thermophilic anaerobic digester. Supplementation of magnetite accelerated methanogenesis from acetate and propionate under thermophilic conditions, while supplementation of ferrihydrite also accelerated methanogenesis from propionate. Microbial community analysis revealed that supplementation of magnetite drastically changed bacterial populations in the methanogenic acetate-degrading cultures, in which Tepidoanaerobacter sp. and Coprothermobacter sp. dominated. These results suggest that supplementation of magnetite induce electric Syntrophy between organic acid-oxidizing bacteria and methanogenic archaea and accelerate methanogenesis even under thermophilic conditions. Findings from this study would provide a possibility for the achievement of stably operating thermophilic anaerobic digestion systems with high efficiency for removal of organics and generation of CH4.
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methanogenesis facilitated by electric Syntrophy via semi conductive iron oxide minerals
Environmental Microbiology, 2012Co-Authors: Souichiro Kato, Kazuya Watanabe, Kazuhito HashimotoAbstract:Summary Methanogenesis is an essential part of the global carbon cycle and a key bioprocess for sustainable energy. Methanogenesis from organic matter is accomplished by syntrophic interactions among different species of microbes, in which interspecies electron transfer (IET) via diffusive carriers (e.g. hydrogen and formate) is known to be the bottleneck step. We report herein that the supplementation of soil microbes with (semi)conductive iron-oxide minerals creates unique interspecies interactions and facilitates methanogenesis. Methanogenic microbes were enriched from rice paddy field soil with either acetate or ethanol as a substrate in the absence or presence of (semi)conductive iron oxides (haematite or magnetite). We found that the supplementation with either of these iron oxides resulted in the acceleration of methanogenesis in terms of lag time and production rate, while the supplementation with an insulative iron oxide (ferrihydrite) did not. Clone-library analyses of 16S rRNA gene fragments PCR-amplified from the enrichment cultures revealed that the iron-oxide supplementation stimulated the growth of Geobacter spp. Furthermore, the addition of a specific inhibitor for methanogenesis suppressed the growth of Geobacter spp. These results suggest that Geobacter grew under syntrophic association with methanogens, and IET could occur via electric currents through (semi)conductive iron-oxide minerals (termed ‘electric Syntrophy’). Given the ubiquity of conductive minerals in nature, such energetic interactions may occur widely in soil and sediments and can be used to develop efficient bioenergy processes.
Alfons J M Stams - One of the best experts on this subject based on the ideXlab platform.
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or methanobacterium thermoformicicum with methanobacterium thermoautotrophicum propionate oxidizing bacteria in Syntrophy enrichment of thermophilic
2013Co-Authors: Jules B Van Lier, K C F Grolle, Alfons J M Stams, C T M J FrijtersAbstract:Above 60 and below 45°C, no growth occurred in cultureswith strain AH. No propionate oxidation occurred whenbacteriawereculturedwithMethanospirillumhungatiiDSM864at 37°C, showingthat the enriched bacteriawereclearlydifferent from previously described mesophilic propionateoxidizers (7, 9, 21).DISCUSSIONResults obtained in this study show clearly that thestability ofmethanogens against starvation is the determin-ing factor for a successful enrichment of thermophilic,
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Syntrophy in methanogenic degradation
(Endo)symbiotic methanogenic archaea 2010 ISBN 364213615X págs. 143-173, 2010Co-Authors: Petra Worm, Alfons J M Stams, Nicolai Muller, Caroline M Plugge, Bernhard SchinkAbstract:This chapter deals with microbial communities of bacteria and archaea that closely cooperate in methanogenic degradation and perform metabolic functions in this community that neither one of them could carry out alone. The methanogenic degradation of fatty acids, alcohols, most aromatic compounds, amino acids, and others is performed in partnership between fermenting bacteria and methanogenic archaea. The energy available in these processes is very small, attributing only fractions of an ATP unit per reaction run to every partner. The biochemical strategies taken include in most cases reactions of substrate-level phosphorylation combined with various kinds of reversed electron transport systems in which part of the gained ATP is reinvested into thermodynamically unfavourable electron transport processes. Altogether, these systems represent fascinating examples of energy efficiency at the lowermost energy level that allows microbial life.
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ecophysiology of syntrophic communities that degrade saturated and unsaturated long chain fatty acids
FEMS Microbiology Ecology, 2009Co-Authors: D Z Sousa, Hauke Smidt, M M Alves, Alfons J M StamsAbstract:Syntrophic relationships are the key for biodegradation in methanogenic environments. We review the ecological and physiological features of syntrophic communities involved in the degradation of saturated and unsaturated long-chain fatty acids (LCFA), as well as their potential application to convert lipids/fats containing waste to biogas. Presently, about 14 species have been described with the ability to grow on fatty acids in Syntrophy with methanogens, all belonging to the families Syntrophomonadaceae and Syntrophaceae. The principle pathway of LCFA degradation is through β-oxidation, but the initial steps in the conversion of unsaturated LCFA are unclear. Communities enriched on unsaturated LCFA also degrade saturated LCFA, but the opposite generally is not the case. For efficient methane formation, the physical and inhibitory effects of LCFA on methanogenesis need to be considered. LCFA adsorbs strongly to biomass, which causes encapsulation of active syntrophic communities and hampers diffusion of substrate and products in and out of the biomass. Quantification of archaea by real-time PCR analysis suggests that potential LCFA inhibitory effect towards methanogens might be reversible. Rather, the conversion of adsorbed LCFA in batch assays was shown to result in a significant increase of archaeal cell numbers in anaerobic sludge samples.
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microbial population dynamics during start up and overload conditions of anaerobic digesters treating municipal solid waste and sewage sludge
Biotechnology and Bioengineering, 2004Co-Authors: Katherine D Mcmahon, Roderick I Mackie, Alfons J M Stams, Dandan Zheng, Lutgarde RaskinAbstract:Microbial population dynamics were investigated during start-up and during periods of overload conditions in anaerobic co-digesters treating municipal solid waste and sewage sludge. Changes in community structure were monitored using ribosomal RNA-based oligonucleotide probe hybridization to measure the abundance of syntrophic propionate-oxidizing bacteria (SPOB), saturated fatty acid-beta-oxidizing syntrophs (SFAS), and methanogens. These changes were linked to traditional performance parameters such as biogas production and volatile fatty acid (VFA) concentrations. Digesters with high levels of Archaea started up successfully. Methanosaeta concilii was the dominant aceticlastic methanogen in these systems. In contrast, digesters that experienced a difficult start-up period had lower levels of Archaea with proportionally more abundant Methanosarcina spp. Syntrophic propionate-oxidizing bacteria and saturated fatty acid-beta-oxidizing syntrophs were present at low levels in all digesters, and SPOB appeared to play a role in stabilizing propionate levels during start-up of one digester. Digesters with a history of poor performance tolerated a severe organic overload event better than digesters that had previously performed well. It is hypothesized that higher levels of SPOB and SFAS and their methanogenic partners in previously unstable digesters are responsible for this behavior. (C) 2004 Wiley Periodicals, Inc.
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microbial population dynamics during start up and overload conditions of anaerobic digesters treating municipal solid waste and sewage sludge
Biotechnology and Bioengineering, 2004Co-Authors: Katherine D Mcmahon, Roderick I Mackie, Alfons J M Stams, Dandan Zheng, Lutgarde RaskinAbstract:Microbial population dynamics were investigated during start-up and during periods of overload conditions in anaerobic co-digesters treating municipal solid waste and sewage sludge. Changes in community structure were monitored using ribosomal RNA-based oligonucleotide probe hybridization to measure the abundance of syntrophic propionate-oxidizing bacteria (SPOB), saturated fatty acid-beta-oxidizing syntrophs (SFAS), and methanogens. These changes were linked to traditional performance parameters such as biogas production and volatile fatty acid (VFA) concentrations. Digesters with high levels of Archaea started up successfully. Methanosaeta concilii was the dominant aceticlastic methanogen in these systems. In contrast, digesters that experienced a difficult start-up period had lower levels of Archaea with proportionally more abundant Methanosarcina spp. Syntrophic propionate-oxidizing bacteria and saturated fatty acid-beta-oxidizing syntrophs were present at low levels in all digesters, and SPOB appeared to play a role in stabilizing propionate levels during start-up of one digester. Digesters with a history of poor performance tolerated a severe organic overload event better than digesters that had previously performed well. It is hypothesized that higher levels of SPOB and SFAS and their methanogenic partners in previously unstable digesters are responsible for this behavior.
Toshiyuki Ueki - One of the best experts on this subject based on the ideXlab platform.
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syntrophus conductive pili demonstrate that common hydrogen donating syntrophs can have a direct electron transfer option
The ISME Journal, 2020Co-Authors: David J F Walker, Kelly P Nevin, Dawn E Holmes, Ameliaelena Rotaru, Joy E Ward, Trevor L Woodard, Jiaxin Zhu, Toshiyuki UekiAbstract:Syntrophic interspecies electron exchange is essential for the stable functioning of diverse anaerobic microbial communities. Hydrogen/formate interspecies electron transfer (HFIT), in which H2 and/or formate function as diffusible electron carriers, has been considered to be the primary mechanism for electron transfer because most common syntrophs were thought to lack biochemical components, such as electrically conductive pili (e-pili), necessary for direct interspecies electron transfer (DIET). Here we report that Syntrophus aciditrophicus, one of the most intensively studied microbial models for HFIT, produces e-pili and can grow via DIET. Heterologous expression of the putative S. aciditrophicus type IV pilin gene in Geobacter sulfurreducens yielded conductive pili of the same diameter (4 nm) and conductance of the native S. aciditrophicus pili and enabled long-range electron transport in G. sulfurreducens. S. aciditrophicus lacked abundant c-type cytochromes often associated with DIET. Pilin genes likely to yield e-pili were found in other genera of hydrogen/formate-producing syntrophs. The finding that DIET is a likely option for diverse syntrophs that are abundant in many anaerobic environments necessitates a reexamination of the paradigm that HFIT is the predominant mechanism for syntrophic electron exchange within anaerobic microbial communities of biogeochemical and practical significance.
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syntrophus conductive pili demonstrate that common hydrogen donating syntrophs can have a direct electron transfer option
bioRxiv, 2018Co-Authors: David J F Walker, Kelly P Nevin, Dawn E Holmes, Ameliaelena Rotaru, Joy E Ward, Trevor L Woodard, Jiaxin Zhu, Toshiyuki UekiAbstract:Abstract Syntrophic interspecies electron exchange is essential for the stable functioning of diverse anaerobic microbial communities. Hydrogen/formate interspecies electron transfer (HFIT), in which H2 and/or formate function as diffusible electron carriers, has been considered to be the primary mechanism for electron sharing because most common syntrophs were thought to lack biochemical components, such as electrically conductive pili (e-pili), necessary for direct interspecies electron transfer (DIET). Here we report that Syntrophus aciditrophicus, one of the most intensively studied microbial models for HFIT, produces e-pili and can grow via DIET. Pilin genes likely to yield e-pili were found in other genera of hydrogen/formate-producing syntrophs. The finding that DIET is a likely option for diverse syntrophs that are abundant in many anaerobic environments necessitates a reexamination of the paradigm that HFIT is the predominant mechanism for syntrophic electron exchange within anaerobic microbial communities of biogeochemical and practical significance.
Kensuke Igarashi - One of the best experts on this subject based on the ideXlab platform.
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Enhancement of methanogenesis by electric Syntrophy with biogenic iron-sulfide minerals.
MicrobiologyOpen, 2018Co-Authors: Souichiro Kato, Kensuke IgarashiAbstract:Recent studies have shown that interspecies electron transfer between chemoheterotrophic bacteria and methanogenic archaea can be mediated by electric currents flowing through conductive iron oxides, a process termed electric Syntrophy. In this study, we conducted enrichment experiments with methanogenic microbial communities from rice paddy soil in the presence of ferrihydrite and/or sulfate to determine whether electric Syntrophy could be enabled by biogenic iron sulfides. Although supplementation with either ferrihydrite or sulfate alone suppressed methanogenesis, supplementation with both ferrihydrite and sulfate enhanced methanogenesis. In the presence of sulfate, ferrihydrite was transformed into black precipitates consisting mainly of poorly crystalline iron sulfides. Microbial community analysis revealed that a methanogenic archaeon and iron- and sulfate-reducing bacteria (Methanosarcina, Geobacter, and Desulfotomaculum, respectively) predominated in the enrichment culture supplemented with both ferrihydrite and sulfate. Addition of an inhibitor specific for methanogenic archaea decreased the abundance of Geobacter, but not Desulfotomaculum, indicating that Geobacter acquired energy via syntrophic interaction with methanogenic archaea. Although electron acceptor compounds such as sulfate and iron oxides have been thought to suppress methanogenesis, this study revealed that coexistence of sulfate and iron oxide can promote methanogenesis by biomineralization of (semi)conductive iron sulfides that enable methanogenesis via electric Syntrophy.
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hydrogen sulfide free methane production by fermenter methanogen Syntrophy using dacite pumice under aerobic gas phase
Energy & Fuels, 2016Co-Authors: Kensuke Igarashi, Tomohiko KuwabaraAbstract:Biological CH4 is produced by the process of Syntrophy between fermenters and methanogens. CH4 from biological waste products is produced by complex syntrophic systems, which additionally include aerobes and facultative anaerobes jointly working to convert various organics to substrates for the fermenters. However, as a result of complexity of the constituents, these systems are prone to environmental changes, such as those in the O2 concentration and pH. Furthermore, H2S from sulfur-containing organics is corrosive to metals in the equipment. Here, we studied the principles of biological CH4 production through establishment of a system where combustible H2S-free CH4 can be produced daily. Toward this objective, we applied a solid-phase cultivation method, using dacite pumice, to a simple syntrophic system of Thermosipho globiformans and Methanocaldococcus jannaschii. Dacite pumice, used as a solid support for anaerobic co-cultivation of these microorganisms, was the inoculum for solid-phase carried-over ...
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fe iii oxides protect fermenter methanogen Syntrophy against interruption by elemental sulfur via stiffening of fe ii sulfides produced by sulfur respiration
Extremophiles, 2014Co-Authors: Kensuke Igarashi, Tomohiko KuwabaraAbstract:Thermosipho globiformans (rod-shaped thermophilic fermenter) and Methanocaldococcus jannaschii (coccal hyperthermophilic hydrogenotrophic methanogen) established H2-mediated Syntrophy at 68 °C, forming exopolysaccharide-based aggregates. Electron microscopy showed that the syntrophic partners connected to each other directly or via intercellular bridges made from flagella, which facilitated transfer of H2. Elemental sulfur (S0) interrupted Syntrophy; polysulfides abiotically formed from S0 intercepted electrons that were otherwise transferred to H+ to produce H2, resulting in the generation of sulfide (sulfur respiration). However, Fe(III) oxides significantly reduced the interruption by S0, accompanied by stiffening of Fe(II) sulfides produced by the reduction of Fe(III) oxides with the sulfur respiration-generated sulfide. Sea sand replacing Fe(III) oxides failed to generate stiffening or protect the Syntrophy. Several experimental results indicated that the stiffening of Fe(II) sulfides shielded the liquid from S0, resulting in methane production in the liquid. Field-emission scanning electron microscopy showed that the stiffened Fe(II) sulfides formed a network of spiny structures in which the microorganisms were buried. The individual fermenter rods likely produced Fe(II) sulfides on their surface and became local centers of a core of spiny structures, and the connection of these cores formed the network, which was macroscopically recognized as stiffening.
Kazuya Watanabe - One of the best experts on this subject based on the ideXlab platform.
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methanogenesis facilitated by electric Syntrophy via semi conductive iron oxide minerals
Environmental Microbiology, 2012Co-Authors: Souichiro Kato, Kazuya Watanabe, Kazuhito HashimotoAbstract:Summary Methanogenesis is an essential part of the global carbon cycle and a key bioprocess for sustainable energy. Methanogenesis from organic matter is accomplished by syntrophic interactions among different species of microbes, in which interspecies electron transfer (IET) via diffusive carriers (e.g. hydrogen and formate) is known to be the bottleneck step. We report herein that the supplementation of soil microbes with (semi)conductive iron-oxide minerals creates unique interspecies interactions and facilitates methanogenesis. Methanogenic microbes were enriched from rice paddy field soil with either acetate or ethanol as a substrate in the absence or presence of (semi)conductive iron oxides (haematite or magnetite). We found that the supplementation with either of these iron oxides resulted in the acceleration of methanogenesis in terms of lag time and production rate, while the supplementation with an insulative iron oxide (ferrihydrite) did not. Clone-library analyses of 16S rRNA gene fragments PCR-amplified from the enrichment cultures revealed that the iron-oxide supplementation stimulated the growth of Geobacter spp. Furthermore, the addition of a specific inhibitor for methanogenesis suppressed the growth of Geobacter spp. These results suggest that Geobacter grew under syntrophic association with methanogens, and IET could occur via electric currents through (semi)conductive iron-oxide minerals (termed ‘electric Syntrophy’). Given the ubiquity of conductive minerals in nature, such energetic interactions may occur widely in soil and sediments and can be used to develop efficient bioenergy processes.
