scholarly journals Extremely ThermoacidophilicMetallosphaeraSpecies Mediate Mobilization and Oxidation of Vanadium and Molybdenum Oxides

2018 ◽  
Vol 85 (5) ◽  
Author(s):  
Garrett H. Wheaton ◽  
Nicholas P. Vitko ◽  
James A. Counts ◽  
Jessica A. Dulkis ◽  
Igor Podolsky ◽  
...  
Keyword(s):  
Solid Phase ◽  
Redox Status ◽  
Vanadium Oxides ◽  
Molybdenum Oxides ◽  
Iron Cycling ◽  
Direct Oxidation ◽  
Reduced Sulfur Compounds ◽  
Transcriptomic Response ◽  
Content Type ◽  
Thermoacidophilic Archaea

ABSTRACTCertain species from the extremely thermoacidophilic genusMetallosphaeradirectly oxidize Fe(II) to Fe(III), which in turn catalyzes abiotic solubilization of copper from chalcopyrite to facilitate recovery of this valuable metal. In this process, the redox status of copper does not change as it is mobilized.Metallosphaeraspecies can also catalyze the release of metals from ores with a change in the metal’s redox state. For example,Metallosphaera sedulacatalyzes the mobilization of uranium from the solid oxide U3O8, concomitant with the generation of soluble U(VI). Here, the mobilization of metals from solid oxides (V2O3, Cu2O, FeO, MnO, CoO, SnO, MoO2, Cr2O3, Ti2O3, and Rh2O3) was examined forM. sedulaandM. prunaeat 70°C and pH 2.0. Of these oxides, only V and Mo were solubilized, a process accelerated in the presence of FeCl3. However, it was not clear whether the solubilization and oxidation of these metals could be attributed entirely to an Fe-mediated indirect mechanism. Transcriptomic analysis for growth on molybdenum and vanadium oxides revealed transcriptional patterns not previously observed for growth on other energetic substrates (i.e., iron, chalcopyrite, organic compounds, reduced sulfur compounds, and molecular hydrogen). Of particular interest was the upregulation of Msed_1191, which encodes a Rieske cytochromeb6fusion protein (Rcbf, referred to here as V/MoxA) that was not transcriptomically responsive during iron biooxidation. These results suggest that direct oxidation of V and Mo occurs, in addition to Fe-mediated oxidation, such that both direct and indirect mechanisms are involved in the mobilization of redox-active metals byMetallosphaeraspecies.IMPORTANCEIn order to effectively leverage extremely thermoacidophilic archaea for the microbially based solubilization of solid-phase metal substrates (e.g., sulfides and oxides), understanding the mechanisms by which these archaea solubilize metals is important. Physiological analysis ofMetallosphaeraspecies growth in the presence of molybdenum and vanadium oxides revealed an indirect mode of metal mobilization, catalyzed by iron cycling. However, since the mobilized metals exist in more than one oxidation state, they could potentially serve directly as energetic substrates. Transcriptomic response to molybdenum and vanadium oxides provided evidence for new biomolecules participating in direct metal biooxidation. The findings expand the knowledge on the physiological versatility of these extremely thermoacidophilic archaea.

scholarly journals Differential RNA Sequencing Implicates Sulfide as the Master Regulator of S 0 Metabolism in Chlorobaculum tepidum and Other Green Sulfur Bacteria

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Jacob M. Hilzinger ◽  
Vidhyavathi Raman ◽  
Kevin E. Shuman ◽  
Brian J. Eddie ◽  
Thomas E. Hanson
Keyword(s):  
Gene Expression ◽  
Elemental Sulfur ◽  
Green Sulfur Bacteria ◽  
Electron Donors ◽  
Reduced Sulfur Compounds ◽  
Promoter Elements ◽  
Content Type ◽  
Sulfur Bacteria ◽  
Chlorobaculum Tepidum ◽  
Green Sulfur

ABSTRACT The green sulfur bacteria ( Chlorobiaceae ) are anaerobes that use electrons from reduced sulfur compounds (sulfide, S 0 , and thiosulfate) as electron donors for photoautotrophic growth. Chlorobaculum tepidum , the model system for the Chlorobiaceae , both produces and consumes extracellular S 0 globules depending on the availability of sulfide in the environment. These physiological changes imply significant changes in gene regulation, which has been observed when sulfide is added to Cba. tepidum growing on thiosulfate. However, the underlying mechanisms driving these gene expression changes, i.e., the specific regulators and promoter elements involved, have not yet been defined. Here, differential RNA sequencing (dRNA-seq) was used to globally identify transcript start sites (TSS) that were present during growth on sulfide, biogenic S 0 , and thiosulfate as sole electron donors. TSS positions were used in combination with RNA-seq data from cultures growing on these same electron donors to identify both basal promoter elements and motifs associated with electron donor-dependent transcriptional regulation. These motifs were conserved across homologous Chlorobiaceae promoters. Two lines of evidence suggest that sulfide-mediated repression is the dominant regulatory mode in Cba. tepidum . First, motifs associated with genes regulated by sulfide overlap key basal promoter elements. Second, deletion of the Cba. tepidum 1277 ( CT1277 ) gene, encoding a putative regulatory protein, leads to constitutive overexpression of the sulfide:quinone oxidoreductase CT1087 in the absence of sulfide. The results suggest that sulfide is the master regulator of sulfur metabolism in Cba. tepidum and the Chlorobiaceae . Finally, the identification of basal promoter elements with differing strengths will further the development of synthetic biology in Cba. tepidum and perhaps other Chlorobiaceae . IMPORTANCE Elemental sulfur is a key intermediate in biogeochemical sulfur cycling. The photoautotrophic green sulfur bacterium Chlorobaculum tepidum either produces or consumes elemental sulfur depending on the availability of sulfide in the environment. Our results reveal transcriptional dynamics of Chlorobaculum tepidum on elemental sulfur and increase our understanding of the mechanisms of transcriptional regulation governing growth on different reduced sulfur compounds. This report identifies genes and sequence motifs that likely play significant roles in the production and consumption of elemental sulfur. Beyond this focused impact, this report paves the way for the development of synthetic biology in Chlorobaculum tepidum and other Chlorobiaceae by providing a comprehensive identification of promoter elements for control of gene expression, a key element of strain engineering.

scholarly journals Analysis of Transcriptomic Response to SO 2 by Oenococcus oeni Growing in Continuous Culture

2021 ◽  
Author(s):  
Cristobal A. Onetto ◽  
Peter J. Costello ◽  
Radka Kolouchova ◽  
Charlotte Jordans ◽  
Jane McCarthy ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacterium ◽  
High Sensitivity ◽  
Malolactic Fermentation ◽  
Oenococcus Oeni ◽  
Low Ph ◽  
Transcriptomic Response ◽  
Content Type ◽  
Bacterium Species ◽  
High Ethanol

Malolactic fermentation is an indispensable step in the elaboration of most wines and is generally performed by Oenococcus oeni , a Gram-positive heterofermentative lactic acid bacterium species. While O. oeni is tolerant to many of the wine stresses, including low pH and high ethanol concentrations, it has high sensitivity to SO 2 , an antiseptic and antioxidant compound regularly used in winemaking.

scholarly journals Transcriptomic Responses in the Bloom-Forming Cyanobacterium Microcystis Induced during Exposure to Zooplankton

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Matthew J. Harke ◽  
Jennifer G. Jankowiak ◽  
Brooke K. Morrell ◽  
Christopher J. Gobler
Keyword(s):  
Secondary Metabolites ◽  
Daphnia Pulex ◽  
Transcriptional Response ◽  
Extracellular Polysaccharides ◽  
Gas Vesicles ◽  
Transcriptomic Response ◽  
Content Type ◽  
Genes Encoding ◽  
Transcriptomic Responses ◽  
Shock Proteins

ABSTRACT The bloom-forming, toxic cyanobacterium Microcystis synthesizes multiple secondary metabolites and has been shown to deter zooplankton grazing. However, the biochemical and/or molecular basis by which Microcystis deters zooplankton remains unclear. This global transcriptomic study explored the response of Microcystis to direct and indirect exposures to multiple densities of two cladoceran grazers, Daphnia pulex and D. magna. Higher densities of both daphnids significantly reduced Microcystis cell densities and elicited a stronger transcriptional response in Microcystis. While many putative grazer deterrence genes (encoding microcystin, aeruginosin, cyanopeptolin, and microviridin) were largely unaffected by zooplankton, transcripts for heat shock proteins (hsp) increased in abundance. Beyond metabolites and hsp, large increases in the abundances of transcripts from photosynthetic processes were observed, evidencing energy acquisition pathways were stimulated by grazing. In addition, transcripts of genes associated with the production of extracellular polysaccharides and gas vesicles significantly increased in abundance. These genes have been associated with colony formation and may have been invoked to deter grazers. Collectively, this study demonstrates that daphnid grazers induce a significant transcriptomic response in Microcystis, suggesting this cyanobacterium upregulates specific biochemical pathways to adapt to predation. IMPORTANCE This work explores the transcriptomic responses of Microcystis aeruginosa following exposure to grazing by two cladocerans, Daphnia magna and D. pulex. Contrary to previous hypotheses, Microcystis did not employ putative grazing deterrent secondary metabolites in response to the cladocerans, suggesting they may have other roles within the cell, such as oxidative stress protection. The transcriptional metabolic signature during intense grazing was largely reflective of a growth and stress response, although increasing abundances of transcripts encoding extracellular polysaccharides and gas vesicles were potentially related to predator avoidance.

scholarly journals Probing of Microbial Biofilm Communities for Coadhesion Partners

2014 ◽  
Vol 80 (21) ◽  
pp. 6583-6590 ◽  
Author(s):  
Stefan Ruhl ◽  
Andreas Eidt ◽  
Holger Melzl ◽  
Udo Reischl ◽  
John O. Cisar
Keyword(s):  
Dental Plaque ◽  
Solid Phase ◽  
Screening Method ◽  
Bacterial Strains ◽  
Mixed Species ◽  
Simple Method ◽  
Content Type ◽  
Glycan Receptors ◽  
Fimbrial Adhesin

ABSTRACTInvestigations of interbacterial adhesion in dental plaque development are currently limited by the lack of a convenient assay to screen the multitude of species present in oral biofilms. To overcome this limitation, we developed a solid-phase fluorescence-based screening method to detect and identify coadhesive partner organisms in mixed-species biofilms. The applicability of this method was demonstrated using coaggregating strains of type 2 fimbrial adhesin-bearing actinomyces and receptor polysaccharide (RPS)-bearing streptococci. Specific adhesin/receptor-mediated coadhesion was detected by overlaying bacterial strains immobilized to a nitrocellulose membrane with a suspended, fluorescein-labeled bacterial partner strain. Coadhesion was comparable regardless of which cell type was labeled and which was immobilized. Formaldehyde treatment of bacteria, either in suspension or immobilized on nitrocellulose, abolished actinomyces type 2 fimbrial adhesin but not streptococcal RPS function, thereby providing a simple method for assigning complementary adhesins and glycan receptors to members of a coadhering pair. The method's broader applicability was shown by overlaying colony lifts of dental plaque biofilm cultures with fluorescein-labeled strains of type 2 fimbriatedActinomyces naeslundiior RPS-bearingStreptococcus oralis. Prominent coadhesion partners included not only streptococci and actinomyces, as expected, but also other bacteria not identified in previous coaggregation studies, such as adhesin- or receptor-bearing strains ofNeisseria pharyngitis,Rothia dentocariosa, andKingella oralis. The ability to comprehensively screen complex microbial communities for coadhesion partners of specific microorganisms opens a new approach in studies of dental plaque and other mixed-species biofilms.

Effect of the use of dry breadcrumb in meatball production on the formation of heterocyclic aromatic amines

2020 ◽  
Vol 122 (7) ◽  
pp. 2105-2119
Author(s):  
Ahmet Korkmaz ◽  
Fatih Oz
Keyword(s):  
Aromatic Amines ◽  
Solid Phase ◽  
Meat Products ◽  
Quality Parameters ◽  
Cooking Loss ◽  
Heterocyclic Aromatic Amines ◽  
Control Group ◽  
Content Type ◽  
Cooking Temperature ◽  
Metal Shaping

PurposeHeterocyclic aromatic amines are mutagenic and/or carcinogenic compounds formed during cooking of meat. Therefore, the formation levels of them should be reduced. For this aim, the purpose of the present study was to determine the effect of dry breadcrumb in meatball production on the formation of heterocyclic aromatic amines. In addition, the effect of dry breadcrumb on some quality parameters of the meatballs was also investigated.Design/methodology/approachMeatball dough with 15 percent fat was divided into four parts, where one group was selected as the control group (without dry breadcrumb). In the other three groups, dry breadcrumb was added in various ratios of 5 percent, 10 percent and 15 percent (w/w). Then, meatball dough was stored at 4 °C for 3 h and shaped into meatballs with a metal shaping device (7 × 1 cm). For some of the quality parameters, water, pH, cooking loss and TBARS analyses were done in the samples. Heterocyclic aromatic amine analysis was done in only cooked samples according to solid phase extraction.FindingsThe use of dry breadcrumb in meatball production decreased water content and cooking loss. As cooking temperature increased, water contents and cooking loss of meatball decreased. PhIP, AαC and MeAαC were not detected in any of the samples analyzed. As cooking temperature increased, total amount of HCAs increased and ranged between 0.05 and 0.51 ng/g. While the use of dry breadcrumb in the meatball production increased IQ content of the meatballs, the use of 5 percent dry breadcrumb caused a decrease in the total HAA content (28.57–66.67 percent) for all cooking temperatures.Originality/valueMany research studies including our study in the literature were conducted on formation and reduction of HAAs in meat and meat products. However, although dry breadcrumb is frequently used both in domestic and commercial meatball formulations; to the best of our knowledge, effect of using dry breadcrumb in meatball production on HAAs formation has not been investigated in the literature. Therefore, in the present study, the effects of the use of dry breadcrumb in meatball production on some quality parameters and formation of HAAs in meatballs cooked at 150 °C, 200 °C and 250 °C were determined.

Free convection in a square porous cavity filled with a nanofluid using thermal non equilibrium and Buongiorno models

2016 ◽  
Vol 26 (3/4) ◽  
pp. 671-693 ◽  
Author(s):  
Ioan Pop ◽  
Mohammad Ghalambaz ◽  
Mikhail Sheremet
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Brownian Motion ◽  
Base Fluid ◽  
Average Nusselt Number ◽  
Solid Phase ◽  
Porous Matrix ◽  
Governing Equations ◽  
Content Type ◽  
Brownian Motion And Thermophoresis

Purpose – The purpose of this paper is to theoretically analysis the steady-state natural convection flow and heat transfer of nanofluids in a square enclosure filled with a porous medium saturated with a nanofluid considering local thermal non-equilibrium (LTNE) effects. Different local temperatures for the solid phase of the nanoparticles, the solid phase of porous matrix and the liquid phase of the base fluid are taken into account. Design/methodology/approach – The Buongiorno’s model, incorporating the Brownian motion and thermophoresis effects, is utilized to take into account the migration of nanoparticles. Using appropriate non-dimensional variables, the governing equations are transformed into the non-dimensional form, and the finite element method is utilized to solve the governing equations. Findings – The results show that the increase of buoyancy ratio parameter (Nr) decreases the magnitude of average Nusselt number. The increase of the nanoparticles-fluid interface heat transfer parameter (Nhp) increases the average Nusselt number for nanoparticles and decreases the average Nusselt number for the base fluid. The nanofluid and porous matrix with large values of modified thermal capacity ratios (γ p and γ s ) are of interest for heat transfer applications. Originality/value – The three phases of nanoparticles, base fluid and the porous matrix are in the LTNE. The effect of mass transfer of nanoparticles due to the Brownian motion and thermophoresis effects are also taken into account.

Hormonal dependency of cerebral meningiomas

1990 ◽  
Vol 73 (5) ◽  
pp. 743-749 ◽  
Author(s):  
Uwe M. H. Schrell ◽  
Eric F. Adams ◽  
Rudolf Fahlbusch ◽  
Robert Greb ◽  
Gustav Jirikowski ◽  
...  
Keyword(s):  
Estrogen Receptors ◽  
Binding Sites ◽  
Solid Phase ◽  
Steroid Receptors ◽  
Progesterone Receptors ◽  
Nuclear Compartment ◽  
Content Type ◽  
High Affinity ◽  
Immunohistochemical Techniques ◽  
Fine Print

✓ Female sex steroid receptors were examined in 50 human cerebral meningiomas. For estrogen receptors, high-affinity binding sites (dissociation constant (Kd): 0.05 to 0.2 nM) were found in the cytosolic fraction with a capacity of less than 4 fmol/mg protein in 10 meningiomas using a dextran-coated charcoal (DCC) assay. In the same cytosolic fraction, the solid-phase enzyme immunoassay revealed only one cytosol with a positive colorimetric reaction equal to 5 fmol/mg protein. However, in the nuclear compartment, none of the tumors stained positively for estrogen receptors with immunohistochemical techniques. In addition, the most convincing evidence for the absence of estrogen receptors was obtained by in situ hybridization using an oligonucleotide probe complementary to a fraction of the human receptor messenger ribonucleic acid (mRNA). In none of the 50 meningiomas was the expression of estrogen mRNA coding for the estrogen receptor detected. For progesterone receptors, high-affinity binding sites (Kd: 0.3 to 2.6 nM) were found in 49 of the 50 tumors using a DCC assay. In the same cytosols, solid-phase enzyme immunoassay revealed that each tumor was positive for progesterone receptors. However, in the nuclear compartment, only five tumors had partially positive staining for progesterone receptors with immunohistochemical techniques. Within the confines of this study, it is concluded that: 1) the estrogen receptor is generally absent in meningioma tissue, and 2) the progesterone receptor is mainly absent in the nuclear compartment, leading to the conclusion that the cytosolic progesterone receptor may be an inactive form. This study suggests that female sex steroid receptors are not primarily involved in the proliferative rate of cerebral meningiomas and that they are of no current significance as markers for adjuvant medical therapy of most meningiomas.

scholarly journals Acid Stress-Mediated Metabolic Shift in Lactobacillus sanfranciscensis LSCE1

2011 ◽  
Vol 77 (8) ◽  
pp. 2656-2666 ◽  
Author(s):  
Diana I. Serrazanetti ◽  
Maurice Ndagijimana ◽  
Sylvain L. Sado-Kamdem ◽  
Aldo Corsetti ◽  
Rudi F. Vogel ◽  
...  
Keyword(s):  
Amino Acid ◽  
Solid Phase ◽  
Acid Stress ◽  
Redox Balance ◽  
Gas Chromatography Mass Spectrometry ◽  
Metabolic Shift ◽  
Content Type ◽  
Lactobacillus Sanfranciscensis ◽  
Branched Chain Amino Acid ◽  
Branched Chain

ABSTRACTLactobacillus sanfranciscensisLSCE1 was selected as a target organism originating from recurrently refreshed sourdough to study the metabolic rerouting associated with the acid stress exposure during sourdough fermentation. In particular, the acid stress induced a metabolic shift toward overproduction of 3-methylbutanoic and 2-methylbutanoic acids accompanied by reduced sugar consumption and primary carbohydrate metabolite production. The fate of labeled leucine, the role of different nutrients and precursors, and the expression of the genes involved in branched-chain amino acid (BCAA) catabolism were evaluated at pH 3.6 and 5.8. The novel application of the program XCMS to the solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) data allowed accurate separation and quantification of 2-methylbutanoic and 3-methylbutanoic acids, generally reported as a cumulative datum. The metabolites coming from BCAA catabolism increased up to seven times under acid stress. The gene expression analysis confirmed that some genes associated with BCAA catabolism were overexpressed under acid conditions. The experiment with labeled leucine showed that 2-methylbutanoic acid originated also from leucine. While the overproduction of 3-methylbutanoic acid under acid stress can be attributed to the need to maintain redox balance, the rationale for the production of 2-methylbutanoic acid from leucine can be found in a newly proposed biosynthesis pathway leading to 2-methylbutanoic acid and 3 mol of ATP per mol of leucine. Leucine catabolism to 3-methylbutanoic and 2-methylbutanoic acids suggests that the switch from sugar to amino acid catabolism supports growth inL. sanfranciscensisin restricted environments such as sourdough characterized by acid stress and recurrent carbon starvation.

scholarly journals Volatile-Sulfur-Compound Profile Distinguishes Burkholderia pseudomallei from Burkholderia thailandensis

2015 ◽  
Vol 53 (3) ◽  
pp. 1009-1011 ◽  
Author(s):  
Timothy J. J. Inglis ◽  
Dorothee R. Hahne ◽  
Adam J. Merritt ◽  
Michael W. Clarke
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Burkholderia Pseudomallei ◽  
Solid Phase Microextraction ◽  
Dimethyl Sulfide ◽  
Sulfur Compound ◽  
Solid Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Burkholderia Thailandensis ◽  
Content Type

Solid-phase microextraction gas chromatography-mass spectrometry (SPME-GCMS) was used to show that dimethyl sulfide produced byBurkholderia pseudomalleiis responsible for its unusual truffle-like smell and distinguishes the species fromBurkholderia thailandensis. SPME-GCMS can be safely used to detect dimethyl sulfide produced by agar-grownB. pseudomallei.

Sardine proteins (Sardina pilchardus) combined with green lemon zest (Citrus latifolia) improve blood pressure, lipid profile and redox status in diabetic hypertensive rats

2018 ◽  
Vol 48 (4) ◽  
pp. 654-668 ◽  
Author(s):  
HadjMostefa Khelladi ◽  
Djamil Krouf ◽  
Nawal Taleb-Dida
Keyword(s):  
Blood Pressure ◽  
Redox Status ◽  
Cardiovascular Complications ◽  
Reduce Blood Pressure ◽  
Diabetic Patients ◽  
Hypertensive Rats ◽  
Content Type ◽  
Protein Group ◽  
Male Wistar Rats ◽  
Tbars Values

Purpose This paper aims to study the effect of green lemon zest combined with sardine proteins in diabetic hypertensive rats (DHRs). Design/methodology/approach Male Wistar rats (n = 30) weighing 250 ± 10 g were divided into five groups. The first group consumed a diet containing 20 per cent casein (C). The other four groups are rendered diabetic by intraperitoneal injection of streptozotocin (40 mg/kg body weight), then hypertensive by subcutaneous implantation controlled time-release pellet containing ouabain (0.25 mg/pellet). One untreated group (DHR) consumed 20 per cent casein and the three other groups consumed the same diet supplemented with 2 per cent green lemon zest (DHR-lz), or with 20 per cent of sardine protein (group DHR-sp) or with the combination of both sardine proteins and green lemon zest (group DHR-sp + lz). Findings DHRs feeding on the combination of both sardine protein (sp) and lemon zest (lz) induced a significant decrease of diastolic blood pressure and heart rates values compared with DHR (p < 0.05). The HDLC values were increased by +55 per cent in DHR-sp + lz compared with DHR group. Moreover, plasma non-HDLC concentrations were decreased significantly compared to DHR, DHR-lz, DHR-sp and C groups. In DHR-sp + lzvs DHR group, TBARS values were decreased by −25 per cent in the liver. Moreover, kidney TBARS were significantly reduced by −66, −51, −65 and −67 per cent compared with C, DHR, DHR-lz and DHR-sp, respectively. Originality/value These results suggest that consumption of green lemon zest combined with sardine proteins can reduce blood pressure and tissue oxidative damage and, therefore, help to prevent cardiovascular complications in hypertensive diabetic patients.

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