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Platinum Group Metal-free Catalysts for Hydrogen Evolution Reaction in Microbial Electrolysis Cells.Chemical Record (New York, N.Y.) Jul 2017Hydrogen gas is a green energy carrier with great environmental benefits. Microbial electrolysis cells (MECs) can convert low-grade organic matter to hydrogen gas with... (Review)
Review
Hydrogen gas is a green energy carrier with great environmental benefits. Microbial electrolysis cells (MECs) can convert low-grade organic matter to hydrogen gas with low energy consumption and have gained a growing interest in the past decade. Cathode catalysts for the hydrogen evolution reaction (HER) present a major challenge for the development and future applications of MECs. An ideal cathode catalyst should be catalytically active, simple to synthesize, durable in a complex environment, and cost-effective. A variety of noble-metal free catalysts have been developed and investigated for HER in MECs, including Nickel and its alloys, MoS , carbon-based catalysts and biocatalysts. MECs in turn can serve as a research platform to study the durability of the HER catalysts. This personal account has reviewed, analyzed, and discussed those catalysts with an emphasis on synthesis and modification, system performance and potential for practical applications. It is expected to provide insights into the development of HER catalysts towards MEC applications.
Topics: Bioelectric Energy Sources; Carbon; Catalysis; Desulfovibrio; Electrolysis; Geobacter; Hydrogen; Metals; Platinum
PubMed: 28375578
DOI: 10.1002/tcr.201700007 -
Journal of Hazardous Materials Jul 2022Mercury (Hg) is a pervasive environmental pollutant and poses serious health concerns as inorganic Hg(II) can be converted to the neurotoxin methylmercury (MeHg), which...
Mercury (Hg) is a pervasive environmental pollutant and poses serious health concerns as inorganic Hg(II) can be converted to the neurotoxin methylmercury (MeHg), which bioaccumulates and biomagnifies in food webs. Phytoplankton, representing the base of aquatic food webs, can take up Hg(II) and influence MeHg production, but currently little is known about how and to what extent phytoplankton may impact Hg(II) methylation by itself or by methylating bacteria it harbors. This study investigated whether some species of phytoplankton could produce MeHg and how the live or dead phytoplankton cells and excreted algal organic matter (AOM) impact Hg(II) methylation by several known methylators, including iron-reducing bacteria (FeRB), Geobacter anodireducens SD-1 and Geobacter sulfurreducens PCA, and the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans ND132 (or Pseudodesulfovibrio mercurii). Our results indicate that, among the 4 phytoplankton species studied, none were capable of methylating Hg(II). However, the presence of phytoplankton cells (either live or dead) from Chlorella vulgaris (CV) generally inhibited Hg(II) methylation by FeRB but substantially enhanced methylation by SRB D. desulfuricans ND132. Enhanced methylation was attributed in part to CV-excreted AOM, which increased Hg(II) complexation and methylation by ND132 cells. In contrast, inhibition of methylation by FeRB was attributed to these bacteria incapable of competing with phytoplankton for Hg(II) binding and uptake. These observations suggest that phytoplankton could play different roles in affecting Hg(II) methylation by the two groups of anaerobic bacteria, FeRB and SRB, and thus shed additional light on how phytoplankton blooms may modulate MeHg production and bioaccumulation in the aquatic environment.
Topics: Bacteria; Chlorella vulgaris; Desulfovibrio; Desulfovibrio desulfuricans; Exudates and Transudates; Iron; Mercury; Methylation; Methylmercury Compounds; Phytoplankton; Sulfates
PubMed: 35398798
DOI: 10.1016/j.jhazmat.2022.128835 -
Environmental Science and Pollution... Jul 2017Anode chamber of a dual chamber microbial fuel cell (MFC) having raw landfill leachate was inoculated with consortium of sulphate-reducing bacteria (SRB) and...
Syntrophic association and performance of Clostridium, Desulfovibrio, Aeromonas and Tetrathiobacter as anodic biocatalysts for bioelectricity generation in dual chamber microbial fuel cell.
Anode chamber of a dual chamber microbial fuel cell (MFC) having raw landfill leachate was inoculated with consortium of sulphate-reducing bacteria (SRB) and sulphide-oxidizing bacteria (SOB) to study the phylogenetic architecture, function and mutualism of anolyte community developed in the reactor. Enriched microbial community was analysed with the help of Illumina MiSeq and indicated the dominance of Firmicutes (41.4%), Clostridia (36.4%) and Clostridium (12.9%) at phylum, class and genus level, respectively. Clostridium was associated with fermentation as well as transfer of electrons to the electrode mediated by ferredoxin. Desulfovibrio (6.7%), Aeromonas (6.6%) and Tetrathiobacter (9.8%) were SRB-SOB associated with direct electron transfer to the electrode. Community analysis disclosed a syntrophic association among novel Firmicutes and Proteobacteria species for bioelectricity generation and degradation of organic matter. Complete removal of chemical oxygen demand was observed from landfill leachate within 3 days of inoculation. Lower oxidative slope and polarization resistance revealed from Tafel analysis backed the feasibility of electron transfer from microbes to anodic electrode and thus development of efficient anode-respiring community. Following enrichment and stabilization of the anodic community, maximum power density achieved was 9.15 W/m and volumetric current density was 16.17 A/m. Simultaneous feeding with SRB-SOB and landfill leachate led to the enrichment of a novel, mutually interdependent microbial community capable of synchronized bioremediation of effluents rich in carbon, sulphate, nitrate and aromatic compounds.
Topics: Aeromonas; Bioelectric Energy Sources; Clostridium; Desulfovibrio; Electrodes; Phylogeny
PubMed: 28537018
DOI: 10.1007/s11356-017-9112-4 -
Applied and Environmental Microbiology Apr 2024Sulfate-reducing prokaryotes (SRPs) are essential microorganisms that play crucial roles in various ecological processes. Even though SRPs have been studied for over a... (Review)
Review
Sulfate-reducing prokaryotes (SRPs) are essential microorganisms that play crucial roles in various ecological processes. Even though SRPs have been studied for over a century, there are still gaps in our understanding of their biology. In the past two decades, a significant amount of data on SRP ecology has been accumulated. This review aims to consolidate that information, focusing on SRPs in soils, their relation to the rare biosphere, uncultured sulfate reducers, and their interactions with other organisms in terrestrial ecosystems. SRPs in soils form part of the rare biosphere and contribute to various processes as a low-density population. The data reveal a diverse range of sulfate-reducing taxa intricately involved in terrestrial carbon and sulfur cycles. While some taxa like and are well studied, others are more enigmatic. For example, members of the Acidobacteriota phylum appear to hold significant importance for the terrestrial sulfur cycle. Many aspects of SRP ecology remain mysterious, including sulfate reduction in different bacterial phyla, interactions with bacteria and fungi in soils, and the existence of soil sulfate-reducing archaea. Utilizing metagenomic, metatranscriptomic, and culture-dependent approaches will help uncover the diversity, functional potential, and adaptations of SRPs in the global environment.
Topics: Ecosystem; Bacteria; Desulfovibrio; Sulfates; Sulfur; Soil
PubMed: 38551370
DOI: 10.1128/aem.01390-23 -
Archives of Microbiology May 2022Bacteria are important participants in sulfur cycle of the extremely haloalkaline environment, e.g. soda lake. The effects of physicochemical factors on the composition...
Bacteria are important participants in sulfur cycle of the extremely haloalkaline environment, e.g. soda lake. The effects of physicochemical factors on the composition of sulfide-oxidizing bacteria (SOB) and sulfate-reducing bacteria (SRB) in soda lake have remained elusive. Here, we surveyed the community structure of total bacteria, SOB and SRB based on 16S rRNA, soxB and dsrB gene sequencing, respectively, in five soda lakes with different physicochemical factors. The results showed that the dominant bacteria belonged to the phyla Proteobacteria, Bacteroidetes, Halanaerobiaeota, Firmicutes and Actinobacteria. SOB and SRB were widely distributed in lakes with different physicochemical characteristics, and the community composition were different. In general, salinity and inorganic nitrogen sources (NH-N, NO-N) were the most significant factors. Specifically, the communities of SOB, mainly including Thioalkalivibrio, Burkholderia, Paracoccus, Bradyrhizobium, and Hydrogenophaga genera, were remarkably influenced by the levels of NH-N and salinity. Yet, for SRB communities, including Desulfurivibrio, Candidatus Electrothrix, Desulfonatronospira, Desulfonatronum, Desulfonatronovibrio, Desulfonatronobacter and so on, the most significant determinants were salinity and NO-N. Besides, Rhodoplanes played a significant role in the interaction between SOB and SRB. From our results, the knowledge regarding the community structures of SOB and SRB in extremely haloalkaline environment was extended.
Topics: Bacteria; Desulfovibrio; Humans; Lakes; Oxidation-Reduction; Phylogeny; RNA, Ribosomal, 16S; Salinity; Sulfides; Sulfur
PubMed: 35567694
DOI: 10.1007/s00203-022-02925-7 -
Characterization of the Bottlenecks and Pathways for Inhibitor Dissociation from [NiFe] Hydrogenase.Journal of Chemical Information and... May 2024[NiFe] hydrogenases can act as efficient catalysts for hydrogen oxidation and biofuel production. However, some [NiFe] hydrogenases are inhibited by gas molecules...
[NiFe] hydrogenases can act as efficient catalysts for hydrogen oxidation and biofuel production. However, some [NiFe] hydrogenases are inhibited by gas molecules present in the environment, such as O and CO. One strategy to engineer [NiFe] hydrogenases and achieve O- and CO-tolerant enzymes is by introducing point mutations to block the access of inhibitors to the catalytic site. In this work, we characterized the unbinding pathways of CO in the complex with the wild-type and 10 different mutants of [NiFe] hydrogenase from using τ-random accelerated molecular dynamics (τRAMD) to enhance the sampling of unbinding events. The ranking provided by the relative residence times computed with τRAMD is in agreement with experiments. Extensive data analysis of the simulations revealed that from the two bottlenecks proposed in previous studies for the transit of gas molecules (residues 74 and 122 and residues 74 and 476), only one of them (residues 74 and 122) effectively modulates diffusion and residence times for CO. We also computed pathway probabilities for the unbinding of CO, O, and H from the wild-type [NiFe] hydrogenase, and we observed that while the most probable pathways are the same, the secondary pathways are different. We propose that introducing mutations to block the most probable paths, in combination with mutations to open the main secondary path used by H, can be a feasible strategy to achieve CO and O resistance in the [NiFe] hydrogenase from .
Topics: Hydrogenase; Molecular Dynamics Simulation; Carbon Monoxide; Desulfovibrio; Enzyme Inhibitors; Mutation; Oxygen; Protein Conformation
PubMed: 38728115
DOI: 10.1021/acs.jcim.4c00187 -
Bioresource Technology Oct 2022Signaling molecules are useful in biofilm formation, but the mechanism for biofilm construction still needs to be explored. In this study, a signaling molecule,...
Signaling molecules are useful in biofilm formation, but the mechanism for biofilm construction still needs to be explored. In this study, a signaling molecule, N-butyryl-l-Homoserine lactone (C-HSL), was supplied to enhance the construction of the sulfate-reducing bacteria (SRB) bio-cathode biofilm in microbial electrolysis cell (MEC). The sulfate reduction efficiency was more than 90% in less time under the system with C-HSL addition. The analysis of SRB bio-cathode biofilms indicated that the activity, distribution, microbial population, and secretion of extracellular polymers prompted by C-HSL, which accelerate the sulfate reduction, in particular for the assimilatory sulfate reduction pathway. Specifically, the relative abundance of acidogenic fermentation bacteria increased, and Desulfovibrio was co-metabolized with acidogenic fermentation bacteria. This knowledge will help to reveal the potential of signaling molecules to enhance the SRB bio-cathode biofilm MEC construction and improve the performance of treating sulfate-containing wastewater.
Topics: Biofilms; Desulfovibrio; Electrodes; Electrolysis; Sulfates; Sulfur Oxides; Wastewater
PubMed: 35905879
DOI: 10.1016/j.biortech.2022.127695 -
Journal of Hazardous Materials Oct 2023Sulfate-reducing bacteria (SRB) were effective in stabilizing Sb. However, the influence of electron donors and acceptors during SRB remediation, as well as the...
Sulfate-reducing bacteria (SRB) were effective in stabilizing Sb. However, the influence of electron donors and acceptors during SRB remediation, as well as the ecological principles involved, remained unclear. In this study, Desulfovibrio desulfuricans ATCC 7757 was utilized to stabilize soil Sb within microcosm. Humic acid (HA) or sodium sulfate (NaSO) were employed to enhance SRB capacity. The SRB+HA treatment exhibited the highest Sb stabilization rate, achieving 58.40%. Bacterial community analysis revealed that SRB altered soil bacterial diversity, community composition, and assembly processes, with homogeneous selection as the predominant assembly processes. When HA and NaSO significantly modified the stimulated microbial community succession trajectories, shaped the taxonomic composition and interactions of the bacterial community, they showed converse effect in shaping bacterial community which were both helpful for promoting dissimilatory sulfate reduction. NaSO facilitated SRB-mediated anaerobic reduction and promoted interactions between SRB and bacteria involved in nitrogen and sulfur cycling. The HA stimulated electron generation and storage, and enhanced the interactions between SRB and bacteria possessing heavy metal tolerance or carbohydrate degradation capabilities.
Topics: Antimony; Oxidation-Reduction; Soil; Biological Availability; Desulfovibrio; Bacteria; Sulfates
PubMed: 37567138
DOI: 10.1016/j.jhazmat.2023.132256 -
Environmental Microbiology Reports Apr 2018A refined Desulfovibrio vulgaris Hildenborough flux balance analysis (FBA) model (iJF744) was developed, incorporating 1016 reactions that include 744 genes and 951...
A refined Desulfovibrio vulgaris Hildenborough flux balance analysis (FBA) model (iJF744) was developed, incorporating 1016 reactions that include 744 genes and 951 metabolites. A draft model was first developed through automatic model reconstruction using the ModelSeed Server and then curated based on existing literature. The curated model was further refined by incorporating three recently proposed redox reactions involving the Hdr-Flx and Qmo complexes and a lactate dehydrogenase (LdhAB, DVU 3027-3028) indicated by mutation and transcript analyses to serve electron transfer reactions central to syntrophic and respiratory growth. Eight different variations of this model were evaluated by comparing model predictions to experimental data determined for four different growth conditions - three for sulfate respiration (with lactate, pyruvate or H /CO -acetate) and one for fermentation in syntrophic coculture. The final general model supports (i) a role for Hdr-Flx in the oxidation of DsrC and ferredoxin, and reduction of NAD in a flavin-based electron confurcating reaction sequence, (ii) a function of the Qmo complex in receiving electrons from the menaquinone pool and potentially from ferredoxin to reduce APS and (iii) a reduction of the soluble DsrC by LdhAB and a function of DsrC in electron transfer reactions other than sulfite reduction.
Topics: Bacterial Proteins; Desulfovibrio vulgaris; Electron Transport; Models, Biological; Mutation; Oxidation-Reduction; Sulfates
PubMed: 29377633
DOI: 10.1111/1758-2229.12619 -
Journal of Environmental Management Aug 2022In treating mine-impacted waters using sulfate-reducing bacteria (SRB), metal inhibition and substrate selection are important factors affecting the efficiency of the...
In treating mine-impacted waters using sulfate-reducing bacteria (SRB), metal inhibition and substrate selection are important factors affecting the efficiency of the bioprocess. This work investigated the role of the substrate (i.e. lactate, formate, glycerol and glucose) on Ni inhibition to SRB with sulfate-reducing activity tests at initial pH 5, 7 and 9 and 100 mg/L of Ni. Results indicated that the type of substrate was a significant factor affecting Ni inhibition in SRB, which was the most negligible in the lactate system, followed by glycerol, glucose, and formate. Although less significant, Ni inhibition also varied with the pH, leading for instance, to a reduction of 77% in the sulfate reducing activity for the formate system, but only of 28% for lactate at pH 5. The added substrate also influenced the precipitation kinetics and the characteristics of the precipitates, reaching Ni precipitation extents above 95%, except for glucose (83.2%).
Topics: Desulfovibrio; Formates; Glucose; Glycerol; Lactates; Sulfates
PubMed: 35550960
DOI: 10.1016/j.jenvman.2022.115216