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Angewandte Chemie (International Ed. in... Apr 2021Storage of solar energy as hydrogen provides a platform towards decarbonizing our economy. One emerging strategy for the production of solar fuels is to use...
Storage of solar energy as hydrogen provides a platform towards decarbonizing our economy. One emerging strategy for the production of solar fuels is to use photocatalytic biohybrid systems that combine the high catalytic activity of non-photosynthetic microorganisms with the high light-harvesting efficiency of metal semiconductor nanoparticles. However, few such systems have been tested for H production. We investigated light-driven H production by three novel organisms, Desulfovibrio desulfuricans, Citrobacter freundii, and Shewanella oneidensis, self-photosensitized with cadmium sulfide nanoparticles, and compared their performance to Escherichia coli. All biohybrid systems produced H from light, with D. desulfuricans-CdS demonstrating the best activity overall and outperforming the other microbial systems even in the absence of a mediator. With this system, H was continuously produced for more than 10 days with a specific rate of 36 μmol g h . High apparent quantum yields of 23 % and 4 % were obtained, with and without methyl viologen, respectively, exceeding values previously reported.
Topics: Cadmium Compounds; Citrobacter freundii; Desulfovibrio desulfuricans; Escherichia coli; Hydrogen; Light; Nanoparticles; Particle Size; Photochemical Processes; Shewanella; Sulfides; Surface Properties
PubMed: 33450130
DOI: 10.1002/anie.202016960 -
Journal of Conservative Dentistry : JCD 2020This study determined the corrosion rate by mass loss caused by oral strains of sulphate-reducing bacteria (SRB) in Kerr endodontic files (KF), aiming the development of...
AIMS
This study determined the corrosion rate by mass loss caused by oral strains of sulphate-reducing bacteria (SRB) in Kerr endodontic files (KF), aiming the development of a biopharmaceutical that facilitates the removal of endodontic limb fragments from root canals.
MATERIALS AND METHODS
Nine new KF were analyzed after immersion in the modified Postgate E culture medium inoculated with oral (84 days), in the consortium (84 days) and environmental (119 days).
RESULTS
Optical microscopy revealed corrosion suggestive areas in all files submitted to immersion in SRB cultures, presenting a statistical difference ( < 0.05) between the samples environmental and KF control and between oral and KF control. Epifluorescence microscopy revealed an active SRB biofilm over the entire metal surface of the KF, as evidenced by the SYTO 9 fluorophore.
CONCLUSION
SRB were capable of promoting biocorrosion in Kerr type endodontic files, but with low rate.
PubMed: 33384495
DOI: 10.4103/JCD.JCD_64_19 -
Food Science & Nutrition Dec 2020Studies have documented the benefits of fish oil in different diseases because of its high n-3 polyunsaturated fatty acid content. However, these studies mostly used...
Studies have documented the benefits of fish oil in different diseases because of its high n-3 polyunsaturated fatty acid content. However, these studies mostly used commercially available fish oil supplements with a ratio of 18/12 for eicosapentaenoic acid and docosahexaenoic acid (DHA). However, increasing DHA content for this commonly used ratio might bring out a varied metabolic effect, which have remained unclear. Thus, in this study, a novel tuna oil (TO) was applied to investigate the effect of high-DHA content on the alteration of the gut microbiota and obesity in high-fat diet mice. The results suggest that high-DHA TO (HDTO) supplementation notably ameliorates obesity and related lipid parameters and restores the expression of lipid metabolism-related genes. The benefits of TOs were derived from their modification of the gut microbiota composition and structure in mice. A high-fat diet triggered an increased / ratio that was remarkably restored by TOs. The number of obesity-promoting bacteria-, , , , , , and was dramatically reduced. , , and , three dysbiosis-related species, were especially regulated by HDTO. Regarding the prevention of obesity, HDTO outperforms the normal TO. Intriguingly, HDTO feeding to HFD-fed mice might alter the arginine and proline metabolism of intestinal microbiota.
PubMed: 33312536
DOI: 10.1002/fsn3.1941 -
Scientific Reports Nov 2020Hydrogen is a key intermediate element in microbial electrosynthesis as a mediator of the reduction of carbon dioxide (CO) into added value compounds. In the present...
Hydrogen is a key intermediate element in microbial electrosynthesis as a mediator of the reduction of carbon dioxide (CO) into added value compounds. In the present work we aimed at studying the biological production of hydrogen in biocathodes operated at - 1.0 V vs. Ag/AgCl, using a highly comparable technology and CO as carbon feedstock. Ten bacterial strains were chosen from genera Rhodobacter, Rhodopseudomonas, Rhodocyclus, Desulfovibrio and Sporomusa, all described as hydrogen producing candidates. Monospecific biofilms were formed on carbon cloth cathodes and hydrogen evolution was constantly monitored using a microsensor. Eight over ten bacteria strains showed electroactivity and H production rates increased significantly (two to eightfold) compared to abiotic conditions for two of them (Desulfovibrio paquesii and Desulfovibrio desulfuricans). D. paquesii DSM 16681 exhibited the highest production rate (45.6 ± 18.8 µM min) compared to abiotic conditions (5.5 ± 0.6 µM min), although specific production rates (per 16S rRNA copy) were similar to those obtained for other strains. This study demonstrated that many microorganisms are suspected to participate in net hydrogen production but inherent differences among strains do occur, which are relevant for future developments of resilient biofilm coated cathodes as a stable hydrogen production platform in microbial electrosynthesis.
Topics: Bacteria; Bacterial Physiological Phenomena; Bioelectric Energy Sources; Biofilms; Biosensing Techniques; Electrochemical Techniques; Hydrogen; RNA, Ribosomal, 16S; Stress, Physiological
PubMed: 33199799
DOI: 10.1038/s41598-020-76694-y -
The Science of the Total Environment Jan 2021Cyanobacterial biomass is a promising natural resource for power generation, through the reactions bio-catalyzed by electrochemically active bacteria (EAB). However, the...
Using easy-to-biodegrade co-substrate to eliminate microcystin toxic on electrochemically active bacteria and enhance bioelectricity generation from cyanobacteria biomass.
Cyanobacterial biomass is a promising natural resource for power generation, through the reactions bio-catalyzed by electrochemically active bacteria (EAB). However, the major limitation is the involvement of Microcystin-LR (MC-LR) in inhibiting EAB activation. In this work, toxic M. aeruginosa biomass was employed as analyte of a microbial fuel cell (MFC), and sodium acetate was applied as easy-to-biodegrade co-substrate to alleviate the MC-LR stress on EAB survival. The running stability was continuously enhanced with the increment of co-substrate concentration. The sufficient co-substrate supply (6.0 mM) eliminated the negative effects of MC-LR on the cyanobacteria biomass fed-MFC performance; it contributed 12.7% extension on the electric cyclic terms and caused the productions of the power density which was comparable and even 3.8% higher than its corresponding control (MFC treated with acetate alone). The co-substrate addition also increased coulombic efficiency by 60.1%, microcystin-LR removal efficiency increased by 64.7%, and diversified the microbial community with more species able to biodegrade the MC-LR, bio-transforming the metabolites and EAB. Microcystin-degrading bacteria, such as Sphingopyxis sp., Burkholderia-Paraburkholderia, and Bacillus sp., were remarkably increased, and EAB, including Shewanella sp., Desulfovibrio desulfuricans, Aeromonas hydrophila, were also much more enriched in co-substrate use protocol. Therefore, this study verified a co-substrate strategy for simultaneously eliminating MC-LR toxin and enhancing bioelectricity generation from cyanobacterial biomass via an MFC.
Topics: Bioelectric Energy Sources; Biomass; Cyanobacteria; Electricity; Microcystins
PubMed: 33182012
DOI: 10.1016/j.scitotenv.2020.142292 -
Frontiers in Microbiology 2020Microorganisms are key players in the transformation of mercury into neurotoxic methylmercury (MeHg). Nevertheless, this mechanism and the opposite MeHg demethylation...
Microorganisms are key players in the transformation of mercury into neurotoxic methylmercury (MeHg). Nevertheless, this mechanism and the opposite MeHg demethylation remain poorly understood. Here, we explored the impact of inorganic mercury (IHg) and MeHg concentrations from 0.05 to 50 μM on the production and degradation of MeHg in two sulfate-reducing bacteria, BerOc1 able to methylate and demethylate mercury and G200 only able to demethylate MeHg. MeHg produced by BerOc1 increased with increasing IHg concentration with a maximum attained for 5 μM, and suggested a saturation of the process. MeHg was mainly found in the supernatant suggesting its export from the cell. Hg L-edge High- Energy-Resolution-Fluorescence-Detected-X-ray-Absorption-Near-Edge-Structure spectroscopy (HERFD-XANES) identified MeHg produced by BerOc1 as MeHg-cysteine form. A dominant tetracoordinated βHgS form was detected for BerOc1 exposed to the lowest IHg concentrations where methylation was detected. In contrast, at the highest exposure (50 μM) where Hg methylation was abolished, Hg species drastically changed suggesting a role of Hg speciation in the production of MeHg. The tetracoordinated βHgS was likely present as nano-particles as suggested by transmission electron microscopy combined to X-ray energy dispersive spectroscopy (TEM-X-EDS) and nano-X ray fluorescence (nano-XRF). When exposed to MeHg, the production of IHg, on the contrary, increased with the increase of MeHg exposure until 50 μM for both BerOc1 and G200 strains, suggesting that demethylation did not require intact biological activity. The formed IHg species were identified as various tetracoordinated Hg-S forms. These results highlight the important role of thiol ligands and Hg coordination in Hg methylation and demethylation processes.
PubMed: 33154741
DOI: 10.3389/fmicb.2020.584715 -
Nature Communications Oct 2020Six CO fixation pathways are known to operate in photoautotrophic and chemoautotrophic microorganisms. Here, we describe chemolithoautotrophic growth of the...
Six CO fixation pathways are known to operate in photoautotrophic and chemoautotrophic microorganisms. Here, we describe chemolithoautotrophic growth of the sulphate-reducing bacterium Desulfovibrio desulfuricans (strain G11) with hydrogen and sulphate as energy substrates. Genomic, transcriptomic, proteomic and metabolomic analyses reveal that D. desulfuricans assimilates CO via the reductive glycine pathway, a seventh CO fixation pathway. In this pathway, CO is first reduced to formate, which is reduced and condensed with a second CO to generate glycine. Glycine is further reduced in D. desulfuricans by glycine reductase to acetyl-P, and then to acetyl-CoA, which is condensed with another CO to form pyruvate. Ammonia is involved in the operation of the pathway, which is reflected in the dependence of the autotrophic growth rate on the ammonia concentration. Our study demonstrates microbial autotrophic growth fully supported by this highly ATP-efficient CO fixation pathway.
Topics: Adenosine Triphosphate; Ammonia; Autotrophic Processes; Bacterial Proteins; Carbon Dioxide; Desulfovibrio desulfuricans; Gene Expression Profiling; Genome, Bacterial; Glycine; Metabolomics
PubMed: 33037220
DOI: 10.1038/s41467-020-18906-7 -
ACS Applied Bio Materials Sep 2020This paper is a continued study on laser cleaning removal of marine microbiofouling from Al alloy surfaces. According to our previous study, it is noted that the...
This paper is a continued study on laser cleaning removal of marine microbiofouling from Al alloy surfaces. According to our previous study, it is noted that the antifouling functions of the generated laser-cleaned metallic surfaces must be highlighted. In this work, the inhibition effectiveness of the laser-cleaned Al alloy surfaces was evaluated using a type of vital marine microorganism, sulfate-reducing bacteria (SRB) subsp. , in a dynamic bacterial solution. Before the immersion tests, the laser-cleaned surfaces with nanostructures were chemically processed into superhydrophilic, superhydrophobic, and ultraslippery surfaces. SRB attachment behaviors as well as inhibition mechanisms of the three surfaces to the SRB settlement were characterized and revealed. The SRB adhering to the above surfaces presented three different morphologies, i.e., broken, dented, and plump cells. Superhydrophilic surfaces unexpectedly showed a not inferior antibacterial ability. A piercing effect of the nanostructures caused nontoxic mechanical damage to the cell membranes. The antiadhesion property of superhydrophobic solid-air hybrid surfaces was unreliable due to the loss of air bubbles. The morphology of the last surviving SRB cells left on the ultraslippery surfaces was basically plump. The stable repellent function of the surfaces was responsible for the vigorous prevention of the adhesion of the SRB. The research results offer an insight into the antibacterial/antiadhesion properties of the laser-cleaned surfaces and a practical value for the periodic service of marine high-end equipment.
PubMed: 35021746
DOI: 10.1021/acsabm.0c00714 -
Systematic and Applied Microbiology Sep 2020Two strains of sulfate-reducing bacteria (J.5.4.2-L4.2.8 and J.3.6.1-H7) were isolated from a pyrite-forming enrichment culture and were compared phylogenetically and...
Desulfolutivibrio sulfoxidireducens gen. nov., sp. nov., isolated from a pyrite-forming enrichment culture and reclassification of Desulfovibrio sulfodismutans as Desulfolutivibrio sulfodismutans comb. nov.
Two strains of sulfate-reducing bacteria (J.5.4.2-L4.2.8 and J.3.6.1-H7) were isolated from a pyrite-forming enrichment culture and were compared phylogenetically and physiologically to the closest related type strain Desulfovibrio sulfodismutans DSM 3696. The isolated strains were vibrio-shaped, motile rods that stained Gram-negative. Growth occurred from 15 to 37°C and within a pH range of 6.5-8.5. Both strains used sulfate, thiosulfate, sulfite, and dimethyl sulfoxide (DMSO) as electron acceptor when grown with lactate. Lactate was incompletely oxidized to acetate. Formate and H were used as electron donor in the presence of acetate. Dismutation of thiosulfate and pyrosulfite was observed. The two new isolates differed from D. sulfodismutans by the utilization of DMSO as electron acceptor, 82% genome-wide average nucleotide identity (ANI) and 32% digital DNA-DNA hybridization (dDDH), thus representing a novel species. The type strain of the type species Desulfovibrio desulfuricans Essex6 revealed merely 88% 16S rRNA gene identity and 49% genome-wide average amino acid identity (AAI) to the new isolates as well as to D. sulfodismutans. Furthermore, the dominance of menaquinone MK-7 over MK-6 and the dominance of ai-C fatty acids were observed not only in the two new isolated strains but also in D. sulfodismutans. Therefore, the definition of a new genus is indicated for which the name Desulfolutivibrio is proposed. We propose for strains J.5.4.2-L4.2.8 and J.3.6.1-H7 the name Desulfolutivibrio sulfoxidireducens gen. nov. sp. nov. with strain J.5.4.2-L4.2.8 defined as type strain. In addition, we propose the reclassification of Desulfovibrio sulfodismutans as Desulfolutivibrio sulfodismutans comb. nov.
Topics: Bacterial Typing Techniques; Culture Media; Desulfovibrio; Dimethyl Sulfoxide; Fatty Acids; Genes, rRNA; Genome, Bacterial; Hydrogen-Ion Concentration; Iron; Oxidation-Reduction; Phylogeny; RNA, Ribosomal, 16S; Sewage; Sulfates; Sulfides; Temperature
PubMed: 32847780
DOI: 10.1016/j.syapm.2020.126105 -
Chemical Communications (Cambridge,... Sep 2020[FeFe] hydrogenases are highly active hydrogen conversion catalysts but are notoriously sensitive to oxidative damage. Redox hydrogels have been used for protecting...
[FeFe] hydrogenases are highly active hydrogen conversion catalysts but are notoriously sensitive to oxidative damage. Redox hydrogels have been used for protecting hydrogenases from both high potential inactivation and oxygen inactivation under turnover conditions. However, [FeFe] hydrogenase containing redox hydrogels must be fabricated under strict anoxic conditions. Sulfide coordination at the active center of the [FeFe] hydrogenase from Desulfovibrio desulfuricans protects this enzyme from oxygen in an inactive state, which can be reactivated upon reduction. Here, we show that this oxygen-stable inactive form of the hydrogenase can be reactivated in a redox hydrogel enabling practical use of this highly O sensitive enzyme without the need for anoxic conditions.
Topics: Biocatalysis; Desulfovibrio desulfuricans; Enzyme Stability; Hydrogels; Hydrogenase; Oxidation-Reduction; Oxygen; Sulfides
PubMed: 32789390
DOI: 10.1039/d0cc03155k