scholarly journals Methanol as an alternative electron donor in chain elongation for butyrate and caproate formation

2016 ◽  
Vol 93 ◽  
pp. 201-208 ◽  
Author(s):  
W.S. Chen ◽  
Y. Ye ◽  
K.J.J. Steinbusch ◽  
D.P.B.T.B. Strik ◽  
C.J.N. Buisman
Keyword(s):  
Electron Donor ◽  
Chain Elongation

scholarly journals Reactor Designs and Configurations for Biological and Bioelectrochemical C1 Gas Conversion: A Review

2021 ◽  
Vol 18 (21) ◽  
pp. 11683
Author(s):  
Azize Ayol ◽  
Luciana Peixoto ◽  
Tugba Keskin ◽  
Haris Nalakath Abubackar
Keyword(s):  
Mass Transfer ◽  
Electron Donor ◽  
Molecular Hydrogen ◽  
Chain Elongation ◽  
Product Portfolio ◽  
Scientific Interest ◽  
Important Challenge ◽  
Poorly Soluble ◽  
Conversion Technologies ◽  
Gas Conversion

Microbial C1 gas conversion technologies have developed into a potentially promising technology for converting waste gases (CO2, CO) into chemicals, fuels, and other materials. However, the mass transfer constraint of these poorly soluble substrates to microorganisms is an important challenge to maximize the efficiencies of the processes. These technologies have attracted significant scientific interest in recent years, and many reactor designs have been explored. Syngas fermentation and hydrogenotrophic methanation use molecular hydrogen as an electron donor. Furthermore, the sequestration of CO2 and the generation of valuable chemicals through the application of a biocathode in bioelectrochemical cells have been evaluated for their great potential to contribute to sustainability. Through a process termed microbial chain elongation, the product portfolio from C1 gas conversion may be expanded further by carefully driving microorganisms to perform acetogenesis, solventogenesis, and reverse β-oxidation. The purpose of this review is to provide an overview of the various kinds of bioreactors that are employed in these microbial C1 conversion processes.

scholarly journals Hydrogen as a Co-electron Donor for Chain Elongation With Complex Communities

2021 ◽  
Vol 9 ◽  
Author(s):  
Flávio C. F. Baleeiro ◽  
Sabine Kleinsteuber ◽  
Heike Sträuber
Keyword(s):  
Microbial Communities ◽  
Electron Donor ◽  
Amplicon Sequencing ◽  
Sensu Stricto ◽  
Lessons Learned ◽  
Electron Donors ◽  
Chain Elongation ◽  
Medium Chain ◽  
16S Rrna Amplicon Sequencing ◽  
Hydrogenotrophic Methanogenesis

Electron donor scarcity is seen as one of the major issues limiting economic production of medium-chain carboxylates from waste streams. Previous studies suggest that co-fermentation of hydrogen in microbial communities that realize chain elongation relieves this limitation. To better understand how hydrogen co-feeding can support chain elongation, we enriched three different microbial communities from anaerobic reactors (A, B, and C with ascending levels of diversity) for their ability to produce medium-chain carboxylates from conventional electron donors (lactate or ethanol) or from hydrogen. In the presence of abundant acetate and CO2, the effects of different abiotic parameters (pH values in acidic to neutral range, initial acetate concentration, and presence of chemical methanogenesis inhibitors) were tested along with the enrichment. The presence of hydrogen facilitated production of butyrate by all communities and improved production of i-butyrate and caproate by the two most diverse communities (B and C), accompanied by consumption of acetate, hydrogen, and lactate/ethanol (when available). Under optimal conditions, hydrogen increased the selectivity of conventional electron donors to caproate from 0.23 ± 0.01 mol e–/mol e– to 0.67 ± 0.15 mol e–/mol e– with a peak caproate concentration of 4.0 g L–1. As a trade-off, the best-performing communities also showed hydrogenotrophic methanogenesis activity by Methanobacterium even at high concentrations of undissociated acetic acid of 2.9 g L–1 and at low pH of 4.8. According to 16S rRNA amplicon sequencing, the suspected caproate producers were assigned to the family Anaerovoracaceae (Peptostreptococcales) and the genera Megasphaera (99.8% similarity to M. elsdenii), Caproiciproducens, and Clostridium sensu stricto 12 (97–100% similarity to C. luticellarii). Non-methanogenic hydrogen consumption correlated to the abundance of Clostridium sensu stricto 12 taxa (p < 0.01). If a robust methanogenesis inhibition strategy can be found, hydrogen co-feeding along with conventional electron donors can greatly improve selectivity to caproate in complex communities. The lessons learned can help design continuous hydrogen-aided chain elongation bioprocesses.

Chain elongation process for caproate production using lactate as electron donor in Megasphaera hexanoica

2021 ◽  
pp. 126660
Author(s):  
Seongcheol Kang ◽  
Hyunjin Kim ◽  
Byoung Seung Jeon ◽  
Okkyoung Choi ◽  
Byoung-In Sang
Keyword(s):  
Electron Donor ◽  
Chain Elongation ◽  
Elongation Process

CO as electron donor for efficient medium chain carboxylate production by chain elongation: Microbial and thermodynamic insights

2020 ◽  
Vol 390 ◽  
pp. 124577
Author(s):  
Chao Liu ◽  
Gang Luo ◽  
Haopeng Liu ◽  
Ziyi Yang ◽  
Irini Angelidaki ◽  
...  
Keyword(s):  
Electron Donor ◽  
Chain Elongation ◽  
Medium Chain

Unravelling a microbial synergy to boost caproate production via carboxylates chain elongation with ethanol

2019 ◽  
Vol 26 (2) ◽  
pp. 63-71
Author(s):  
Ling Leng ◽  
Ying Wang ◽  
Peixian Yang ◽  
Takashi Narihiro ◽  
Masaru Konishi Nobu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Microbial Consortia ◽  
Chain Elongation ◽  
Desulfovibrio Vulgaris ◽  
Rrna Gene ◽  
Selective Enrichment ◽  
Microbial Network ◽  
Cost Efficient ◽  
Rrna Gene Sequencing

Chain elongation of volatile fatty acids for medium chain fatty acids production (e.g. caproate) is an attractive approach to treat wastewater anaerobically and recover resource simultaneously. Undefined microbial consortia can be tailored to achieve chain elongation process with selective enrichment from anaerobic digestion sludge, which has advantages over pure culture approach for cost-efficient application. Whilst the metabolic pathway of the dominant caproate producer, Clostridium kluyveri, has been annotated, the role of other coexisting abundant microbiomes remained unclear. To this end, an ethanol-acetate fermentation inoculated with fresh digestion sludge at optimal conditions was conducted. Also, physiological study, thermodynamics and 16 S rRNA gene sequencing to elucidate the biological process by linking the system performance and dominant microbiomes were integrated. Results revealed a possible synergistic network in which C. kluyveri and three co-dominant species, Desulfovibrio vulgaris, Fusobacterium varium and Acetoanaerobium sticklandii coexisted. D. vulgaris and A. sticklandii (F. varium) were likely to boost the carboxylates chain elongation by stimulating ethanol oxidation and butyrate production through a syntrophic partnership with hydrogen (H2) serving as an electron messenger. This study unveils a synergistic microbial network to boost caproate production in mixed culture carboxylates chain elongation.

Metal-Free Photoinduced Hydroalkylation Cascade Enabled by an Electron-Donor-Acceptor Complex

2020 ◽  
Author(s):  
José Tiago Menezes Correia ◽  
Gustavo Piva da Silva ◽  
Camila Menezes Kisukuri ◽  
Elias André ◽  
Bruno Pires ◽  
...  
Keyword(s):  
Electron Donor ◽  
Functional Group ◽  
Photoexcited Electron ◽  
One Pot ◽  
Quaternary Centers ◽  
Metal Free ◽  
Acceptor Complex ◽  
Catalyst Free ◽  
Donor Acceptor ◽  
Radical Cascade

A metal- and catalyst-free photoinduced radical cascade hydroalkylation of 1,7-enynes has been disclosed. The process is triggered by a SET event involving a photoexcited electron-donor-aceptor complex between NHPI ester and Hantzsch ester, which decomposes to afford a tertiary radical that is readily trapped by the enyne. <a>The method provides an operationally simple, robust and step-economical approach to the construction of diversely functionalized dihydroquinolinones bearing quaternary-centers. A sequential one-pot hydroalkylation-isomerization approach is also allowed giving access to a family of quinolinones. A wide substrate scope and high functional group tolerance was observed in both approaches</a>.

Three-Phase Electrochemistry of a Highly Lipophilic Neutral Ru-Complex Having a Tridentate Bis(benzimidazolate)pyridine Ligand

2020 ◽  
Author(s):  
Vishwanath R.S ◽  
Masa-aki Haga ◽  
Takumi Watanabe ◽  
Emilia Witkowska Nery ◽  
Martin Jönsson-Niedziolka
Keyword(s):  
Redox Potential ◽  
Organic Phase ◽  
Electron Donor ◽  
Ion Transfer ◽  
Neutral Complex ◽  
Pyridine Ligand ◽  
Electrochemical Testing ◽  
Ru Complex ◽  
Three Phase ◽  
Exceptional Stability

Here we describe the synthesis and electrochemical testing of a heteroleptic bis(tridentate) ruthenium(II) complex [Ru<sup>II</sup>(LR)(L)]<sup>0</sup> (LR =2,6-bis(1-(2-octyldodecan)benzimidazol-2-yl)pyridine, L = 2,6-bis(benzimidazolate)pyridine). It is a neutral complex which undergoes a quasireversible oxidation and reduction at relatively low potential. The newly synthetized compound was used for studies of ion-transfer at the three-phase junction because of the sensitivity of this method to cation expulsion. The [Ru<sup>II</sup>(LR)(L)]<sup>0</sup> shows exceptional stability during cycling and is sufficiently lipophilic even after oxidation to persist in the organic phase also using very hydrophilic anions such as Cl<sup>−</sup>. Given its low redox potential and strong lipophilicity this compound will be of interest as an electron donor in liquid-liquid electrochemistry.

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