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Anaerobe Jun 2022Desulfovibrio spp. is a commensal sulfate reducing bacterium that is present in small numbers in the gastrointestinal tract. Increased concentrations of Desulfovibrio...
UNLABELLED
Desulfovibrio spp. is a commensal sulfate reducing bacterium that is present in small numbers in the gastrointestinal tract. Increased concentrations of Desulfovibrio spp. (blooms) have been reported in patients with inflammatory bowel disease and irritable bowel syndrome. Since stress has been reported to exacerbate symptoms of these chronic diseases, this study examined whether the stress catecholamine norepinephrine (NE) promotes Desulfovibrio growth. Norepinephrine-stimulated growth has been reported in other bacterial taxa, and this effect may depend on the availability of the micronutrient iron.
OBJECTIVES
This study tested whether norepinephrine exposure affects the in vitro growth of Desulfovibrio vulgaris in an iron dependent manner.
METHODS
DSV was incubated in a growth medium with and without 1 μm of norepinephrine. An additional growth assay added the iron chelator deferoxamine in NE exposed DSV. Iron regulatory genes were assessed with and without the treatment of NE and Deferoxamine.
RESULTS
We found that norepinephrine significantly increased growth of D. vulgaris. Norepinephrine also increased bacterial production of hydrogen sulfide. Additionally, norepinephrine significantly increased bacterial expression in three of the four tested iron regulatory genes. The iron chelator deferoxamine inhibited growth of D. vulgaris in a dose-dependent manner and reversed the effect of norepinephrine on proliferation of D. vulgaris and on bacterial expression of iron regulatory genes.
CONCLUSION
The data presented in this work suggests that promotion of D. vulgaris growth by norepinephrine is iron dependent.
Topics: Deferoxamine; Desulfovibrio; Desulfovibrio vulgaris; Humans; Iron; Iron Chelating Agents; Norepinephrine
PubMed: 35533828
DOI: 10.1016/j.anaerobe.2022.102582 -
Journal of the American Chemical Society Jan 2020[FeFe] hydrogenases are extremely active H-converting enzymes. Their mechanism remains highly controversial, in particular, the nature of the one-electron and...
[FeFe] hydrogenases are extremely active H-converting enzymes. Their mechanism remains highly controversial, in particular, the nature of the one-electron and two-electron reduced intermediates called HH and HH. In one model, the HH and HH states contain a semibridging CO, while in the other model, the bridging CO is replaced by a bridging hydride. Using low-temperature IR spectroscopy and nuclear resonance vibrational spectroscopy, together with density functional theory calculations, we show that the bridging CO is retained in the HH and HH states in the [FeFe] hydrogenases from and , respectively. Furthermore, there is no evidence for a bridging hydride in either state. These results agree with a model of the catalytic cycle in which the HH and HH states are integral, catalytically competent components. We conclude that proton-coupled electron transfer between the two subclusters is crucial to catalysis and allows these enzymes to operate in a highly efficient and reversible manner.
Topics: Carbon Monoxide; Chlamydomonas reinhardtii; Density Functional Theory; Desulfovibrio desulfuricans; Electron Transport; Hydrogenase; Iron-Sulfur Proteins; Nuclear Magnetic Resonance, Biomolecular; Spectroscopy, Fourier Transform Infrared
PubMed: 31820961
DOI: 10.1021/jacs.9b09745 -
Microbiome Dec 2018Currently, the effect of the bacterial community on cast iron corrosion process does not reach consensus. Moreover, some studies have produced contrasting results,...
BACKGROUND
Currently, the effect of the bacterial community on cast iron corrosion process does not reach consensus. Moreover, some studies have produced contrasting results, suggesting that bacteria can either accelerate or inhibit corrosion.
RESULTS
The long-term effects of the bacterial community on cast iron corrosion in reclaimed wastewater distribution systems were investigated from both spatial (yellow layer vs. black layer) and temporal (1-year dynamic process) dimensions of the iron coupon-reclaimed wastewater microcosm using high-throughput sequencing and flow cytometry approaches. Cast iron coupons in the NON and UV reactors suffered more severe corrosion than did those in the NaClO reactor. The bacterial community significantly promoted cast iron corrosion, which was quantified for the first time in the practical reclaimed wastewater and found to account for at least 30.5% ± 9.7% of the total weight loss. The partition of yellow and black layers of cast iron corrosion provided more accurate information on morphology and crystal structures for corrosion scales. The black layer was dense, and the particles looked fusiform, while the yellow layer was loose, and the particles were ellipse or spherical. Goethite was the predominant crystalline phase in black layers, while corrosion products mainly existed as an amorphous phase in yellow layers. The bacterial community compositions of black layers were distinctly separated from yellow layers regardless of disinfection methods. The NON and UV reactors had a more similar microbial composition and variation tendency for the same layer type than did the NaClO reactor. Biofilm development can be divided into the initial start-up stage, mid-term development stage, and terminal stable stage. In total, 12 potential functional genera were selected to establish a cycle model for Fe, N, and S metabolism. Desulfovibrio was considered to accelerate the transfer of Fe to Fe and speed up weight loss.
CONCLUSION
The long-term effect of disinfection processes on corrosion behaviors of cast iron in reclaimed wastewater distribution systems and the hidden mechanisms were deciphered for the first time. This study established a cycle model for Fe, N, and S metabolism that involved 12 functional genera and discovered the significant contribution of Desulfovibrio in promoting corrosion.
Topics: Bacteria; Biofilms; Bioreactors; Corrosion; DNA, Bacterial; Desulfovibrio; High-Throughput Nucleotide Sequencing; Iron; Iron Compounds; Minerals; Sequence Analysis, DNA; Spatio-Temporal Analysis; Wastewater
PubMed: 30545419
DOI: 10.1186/s40168-018-0610-5 -
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 -
MBio Apr 2023Desulfovibrio vulgaris has been a primary pure culture sulfate reducer for developing microbial corrosion concepts. Multiple mechanisms for how it accepts electrons from...
Desulfovibrio vulgaris has been a primary pure culture sulfate reducer for developing microbial corrosion concepts. Multiple mechanisms for how it accepts electrons from Fe have been proposed. We investigated Fe oxidation with a mutant of in which hydrogenase genes were deleted. The hydrogenase mutant grew as well as the parental strain with lactate as the electron donor, but unlike the parental strain, it was not able to grow on H. The parental strain reduced sulfate with Fe as the sole electron donor, but the hydrogenase mutant did not. H accumulated over time in Fe cultures of the hydrogenase mutant and sterile controls but not in parental strain cultures. Sulfide stimulated H production in uninoculated controls apparently by both reacting with Fe to generate H and facilitating electron transfer from Fe to H. Parental strain supernatants did not accelerate H production from Fe, ruling out a role for extracellular hydrogenases. Previously proposed electron transfer between Fe and via soluble electron shuttles was not evident. The hydrogenase mutant did not reduce sulfate in the presence of Fe and either riboflavin or anthraquinone-2,6-disulfonate, and these potential electron shuttles did not stimulate parental strain sulfate reduction with Fe as the electron donor. The results demonstrate that primarily accepts electrons from Fe via H as an intermediary electron carrier. These findings clarify the interpretation of previous corrosion studies and suggest that H-mediated electron transfer is an important mechanism for iron corrosion under sulfate-reducing conditions. Microbial corrosion of iron in the presence of sulfate-reducing microorganisms is economically significant. There is substantial debate over how microbes accelerate iron corrosion. Tools for genetic manipulation have only been developed for a few Fe(III)-reducing and methanogenic microorganisms known to corrode iron and in each case those microbes were found to accept electrons from Fe via direct electron transfer. However, iron corrosion is often most intense in the presence of sulfate-reducing microbes. The finding that Desulfovibrio vulgaris relies on H to shuttle electrons between Fe and cells revives the concept, developed in some of the earliest studies on microbial corrosion, that sulfate reducers consumption of H is a major microbial corrosion mechanism. The results further emphasize that direct Fe-to-microbe electron transfer has yet to be rigorously demonstrated in sulfate-reducing microbes.
Topics: Iron; Desulfovibrio vulgaris; Hydrogenase; Corrosion; Oxidation-Reduction; Lactic Acid; Sulfates; Desulfovibrio
PubMed: 36786581
DOI: 10.1128/mbio.00076-23 -
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 -
Oxygen isotope effects during microbial sulfate reduction: applications to sediment cell abundances.The ISME Journal Jun 2020The majority of anaerobic biogeochemical cycling occurs within marine sediments. To understand these processes, quantifying the distribution of active cells and gross...
The majority of anaerobic biogeochemical cycling occurs within marine sediments. To understand these processes, quantifying the distribution of active cells and gross metabolic activity is essential. We present an isotope model rooted in thermodynamics to draw quantitative links between cell-specific sulfate reduction rates and active sedimentary cell abundances. This model is calibrated using data from a series of continuous culture experiments with two strains of sulfate reducing bacteria (freshwater bacterium Desulfovibrio vulgaris strain Hildenborough, and marine bacterium Desulfovibrio alaskensis strain G-20) grown on lactate across a range of metabolic rates and ambient sulfate concentrations. We use a combination of experimental sulfate oxygen isotope data and nonlinear regression fitting tools to solve for unknown kinetic, step-specific oxygen isotope effects. This approach enables identification of key isotopic reactions within the metabolic pathway, and defines a new, calibrated framework for understanding oxygen isotope variability in sulfate. This approach is then combined with porewater sulfate/sulfide concentration data and diagenetic modeling to reproduce measured O/O in porewater sulfate. From here, we infer cell-specific sulfate reduction rates and predict abundance of active cells of sulfate reducing bacteria, the result of which is consistent with direct biological measurements.
Topics: Bacteria; Desulfovibrio; Oxidation-Reduction; Oxygen Isotopes; Sulfates; Sulfides; Sulfur Oxides
PubMed: 32152390
DOI: 10.1038/s41396-020-0618-2 -
Chemosphere Oct 2018In this study, axenic cultures of sulfate-reducing (SRB) and nitrate-reducing (NRB) bacteria were examined for their ability to methylate inorganic tin and to methylate...
In this study, axenic cultures of sulfate-reducing (SRB) and nitrate-reducing (NRB) bacteria were examined for their ability to methylate inorganic tin and to methylate or dealkylate butyltin compounds. Environmentally relevant concentrations of natural abundance tributyltin (TBT) and Sn-enriched inorganic tin were added to bacterial cultures to identify bacterial-mediated methylation and dealkylation reactions. The results show that none of the Desulfovibrio strains tested was able to induce any transformation process. In contrast, Desulfobulbus propionicus strain DSM-6523 degraded TBT either under sulfidogenic or non-sulfidogenic conditions. In addition, it was able to alkykate Sn-enriched inorganic tin leading to the formation of more toxic dimethyltin and trimethyltin. A similar capacity was observed for incubations of Pseudomonas but with a much greater dealkykation of TBT. As such, Pseudomonas sp. ADR42 degraded 61% of the initial TBT under aerobic conditions and 35% under nitrate-reducing conditions. This is the first work reporting a simultaneous TBT degradation and a methylation of both inorganic tin species and TBT dealkykation products by SRB and NRB under anoxic conditions. These reactions are environmentally relevant as they can control the mobility of these compounds in aquatic ecosystems; as well as their toxicity toward resident organisms.
Topics: Desulfovibrio; Methylation; Nitrates; Organotin Compounds; Sulfates; Sulfur-Reducing Bacteria; Trialkyltin Compounds
PubMed: 30068030
DOI: 10.1016/j.chemosphere.2018.06.030 -
Journal of Ethnopharmacology May 2019Licorice and Yuanhua are both famous herbs in Traditional Chinese Medicine (TCM), and their combination is used by some TCM doctors to treat renal and gastrointestinal...
ETHNOPHARMACOLOGICAL RELEVANCE
Licorice and Yuanhua are both famous herbs in Traditional Chinese Medicine (TCM), and their combination is used by some TCM doctors to treat renal and gastrointestinal diseases as well as tumors. On the other hand, the compatibility theory of TCM warns that toxic effects might be triggered by Licorice-Yuanhua combination. The usability of Licorice-Yuanhua combination has long been controversial due to lack of evidence and mechanism illustration. Colonic hydrogen sulfide (HS) metabolism imbalance is closely related with colonic inflammation, tumor promotion and many other diseases.
AIM OF THE STUDY
This study was carried out to investigate if licorice-Yuanhua combination could induce potential toxic effects in the aspect of colonic HS metabolism.
MATERIALS AND METHODS
Normal mice were treated with high or low doses of Licorice, Yuanhua and Licorice-Yuanhua combination. Fecal HS concentration was measured by colorimetric method, colon sulfomucin production was compared through tissue staining, fecal microbiota and microbial metagenomes were analyzed by 16S rDNA sequencing and data mining.
RESULTS
Data shows that although licorice cannot change colonic HS concentration, it can exacerbate Yuanhua induced HS rising. Licorice or Yuanhua increases colon sulfomucin production, and their combination further enhances this effect. 16S rDNA sequencing analysis revealed that licorice or Yuanhua has little influence on gut microbiota, however, licorice-Yuanhua combination can impact gut microbiota structural balance and increase the abundance of Desulfovibrio genus and other related genera. Moreover, the combination extensively changes microbial metagenomes, influencing 1172 genes that cannot be changed by individual licorice or Yuanhua. By searching in KEGG database, ten genes are annotated with HS producing gene, and these genes are remarkably increased by licorice-Yuanhua combination, more significantly than licorice or Yuanhua.
CONCLUSIONS
This study provides evidences and mechanisms for licorice induced risks, which is related with colonic HS metabolism disturbance, gut microbiota and microbial metagenomes. More risk assessment should be evaluated when licorice was used in combination with foods, herbs or drugs. The study provides an example where healthy risks can be induced by combination of food additive, herbs or drugs, through regulating gut microbiota and its metagenomes.
Topics: Animals; Colon; Daphne; Desulfovibrio; Drug Synergism; Drugs, Chinese Herbal; Feces; Flowers; Gastrointestinal Microbiome; Glycyrrhiza; Hydrogen Sulfide; Male; Medicine, Chinese Traditional; Metagenome; Mice, Inbred ICR; Plant Roots
PubMed: 30851368
DOI: 10.1016/j.jep.2019.01.042 -
The Journal of Biological Chemistry Aug 2023The obligately anaerobic sulfite-reducing bacterium Bilophila wadsworthia is a common human pathobiont inhabiting the distal intestinal tract. It has a unique ability to...
The obligately anaerobic sulfite-reducing bacterium Bilophila wadsworthia is a common human pathobiont inhabiting the distal intestinal tract. It has a unique ability to utilize a diverse range of food- and host-derived sulfonates to generate sulfite as a terminal electron acceptor (TEA) for anaerobic respiration, converting the sulfonate sulfur to HS, implicated in inflammatory conditions and colon cancer. The biochemical pathways involved in the metabolism of the C2 sulfonates isethionate and taurine by B. wadsworthia were recently reported. However, its mechanism for metabolizing sulfoacetate, another prevalent C2 sulfonate, remained unknown. Here, we report bioinformatics investigations and in vitro biochemical assays that uncover the molecular basis for the utilization of sulfoacetate as a source of TEA (STEA) for B. wadsworthia, involving conversion to sulfoacetyl-CoA by an ADP-forming sulfoacetate-CoA ligase (SauCD), and stepwise reduction to isethionate by NAD(P)H-dependent enzymes sulfoacetaldehyde dehydrogenase (SauS) and sulfoacetaldehyde reductase (TauF). Isethionate is then cleaved by the O-sensitive isethionate sulfolyase (IseG), releasing sulfite for dissimilatory reduction to HS. Sulfoacetate in different environments originates from anthropogenic sources such as detergents, and natural sources such as bacterial metabolism of the highly abundant organosulfonates sulfoquinovose and taurine. Identification of enzymes for anaerobic degradation of this relatively inert and electron-deficient C2 sulfonate provides further insights into sulfur recycling in the anaerobic biosphere, including the human gut microbiome.
Topics: Humans; Alkanesulfonates; Bilophila; Sulfites; Sulfur; Taurine; Gastrointestinal Microbiome
PubMed: 37414148
DOI: 10.1016/j.jbc.2023.105010