Organic Sulfur Compounds Research Articles

Oxidative Methods for the Study of the Structural Group Composition of Organosulfur Compounds

The composition of the organosulfur compounds of the oil fraction of Arlan oil was studied using a method involving the two-step oxidation of these compounds with 30% hydrogen peroxide in the presence of an acid catalyst at 80° and 100°C. Vacuum distillation of the organosulfur compounds into narrow fractions showed that the sulfoxides obtained by oxidation of the organic sulfur compounds of the oil fraction are thiamono-, thiabi-, and thiatricycloalkanes, aliphatic sulfides, and alkylcycloalkyl sulfides. No aromatic compounds were detected in the sulfoxides. Sulfones in the narrow fractions are mainly represented by thiaindanes, alkylcyclano- and alkylbicyclanobenzthiophenes with long alkyl substituents containing from 10 to 15 carbon atoms.

Different lactic acid bacteria strains affecting the flavor profile of fermented jujube juice

Jujube juice was separately undergoing controlled lactic acid fermentation at 37°C for 24 hr with 90 different lactic acid bacteria (LAB) strains comprising 30 Lactobacillus casei strains, 30 Lactobacillus plantarum strains, and 30 Enterococcus faecium strains. Electronic nose and Electronic tongue combined with multivariate statistical analysis methods were applied for the investigation of how different LAB strains affecting the flavor profile of fermented jujube juice. A clear distinction of all the fermented jujube juice was achieved. It was found that compared with L. casei-fermented jujube juice and E. faecium-fermented jujube juice, L. plantarum-fermented jujube juice produce more aromatics compounds and less sulfur organic compounds, while its taste is mostly characterized by sourness, and is perceived less bitterness and astringent for better consumer preference. What's more, the high acid-producing ability of L. plantarum may contribute to an extension of microbial safety and shelf life for the product. Practical applications L. plantarum is considered as a microorganism with a documented history of food use with the generally recognized as safe (GRAS) status from the US Food and Drug Administration (US FDA) and the qualified presumption of safety (QPS) status from the European Food Safety Authorities (EFSA). Based on the findings of this research, L. plantarum could improve the flavor profile of the jujube juice and may contribute to an extension of microbial safety and shelf life for the product leads to antibacterial an excellent potential for future research and development.

Shotgun metagenomic sequencing from Manao-Pee cave, Thailand, reveals insight into the microbial community structure and its metabolic potential

BackgroundDue to the cave oligotrophic environment, this habitat presents a challenge for microorganisms to colonize and thrive. However, it has been well documented that microorganisms play important roles in cave development. Survival of microbes in this unique habitat likely involves a broad range of adaptive capabilities. Recently, cave microbiomes all over the world are of great scientific interest. However, the majority of investigations focused mostly on small subunit ribosomal RNA (16S rRNA) gene, leaving the ecological role of the microbial community largely unknown. Here, we are particularly interested in exploring the taxonomic composition and metabolic potential of microorganisms in soil from Manao-Pee cave, a subterranean limestone cave in the western part of Thailand, by using high-throughput shotgun metagenomic sequencing.ResultsFrom taxonomic composition analysis using ribosomal RNA genes (rRNA), the results confirmed that Actinobacteria (51.2%) and Gammaproteobacteria (24.4%) were the dominant bacterial groups in the cave soil community. Metabolic potential analysis, based on six functional modules of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, revealed that functional genes involved in microbial metabolisms are highly represented in this community (40.6%). To better understand how microbes thrive under unfavorable cave condition, we focused on microbial energy metabolism. The results showed that microbial genes involved in oxidative phosphorylation were the most dominant (28.8%) in Manao-Pee cave, and were followed by methane metabolism (20.5%), carbon fixation (16.0%), nitrogen metabolism (14.7%), and sulfur metabolism (6.3%). In addition, microbial genes involved in xenobiotic biodegradation (26 pathways) and in production of secondary metabolites (27 pathways) were also identified.ConclusionIn addition to providing information on microbial diversity, we also gained insights into microbial adaptations and survival strategies under cave conditions. Based on rRNA genes, the results revealed that bacteria belonging to the Actinobacteria and Gammaproteobacteria were the most abundant in this community. From metabolic potential analysis, energy and nutrient sources that sustain diverse microbial population in this community might be atmospheric gases (methane, carbon dioxide, nitrogen), inorganic sulfur, and xenobiotic compounds. In addition, the presence of biosynthetic pathways of secondary metabolites suggested that they might play important ecological roles in the cave microbiome.

Sulfur-Oxidizing Symbionts without Canonical Genes for Autotrophic CO2 Fixation.

Since the discovery of symbioses between sulfur-oxidizing (thiotrophic) bacteria and invertebrates at hydrothermal vents over 40 years ago, it has been assumed that autotrophic fixation of CO2 by the symbionts drives these nutritional associations. In this study, we investigated "Candidatus Kentron," the clade of symbionts hosted by Kentrophoros, a diverse genus of ciliates which are found in marine coastal sediments around the world. Despite being the main food source for their hosts, Kentron bacteria lack the key canonical genes for any of the known pathways for autotrophic carbon fixation and have a carbon stable isotope fingerprint that is unlike other thiotrophic symbionts from similar habitats. Our genomic and transcriptomic analyses instead found metabolic features consistent with growth on organic carbon, especially organic and amino acids, for which they have abundant uptake transporters. All known thiotrophic symbionts have converged on using reduced sulfur to gain energy lithotrophically, but they are diverse in their carbon sources. Some clades are obligate autotrophs, while many are mixotrophs that can supplement autotrophic carbon fixation with heterotrophic capabilities similar to those in Kentron. Here we show that Kentron bacteria are the only thiotrophic symbionts that appear to be entirely heterotrophic, unlike all other thiotrophic symbionts studied to date, which possess either the Calvin-Benson-Bassham or the reverse tricarboxylic acid cycle for autotrophy.IMPORTANCE Many animals and protists depend on symbiotic sulfur-oxidizing bacteria as their main food source. These bacteria use energy from oxidizing inorganic sulfur compounds to make biomass autotrophically from CO2, serving as primary producers for their hosts. Here we describe a clade of nonautotrophic sulfur-oxidizing symbionts, "Candidatus Kentron," associated with marine ciliates. They lack genes for known autotrophic pathways and have a carbon stable isotope fingerprint heavier than other symbionts from similar habitats. Instead, they have the potential to oxidize sulfur to fuel the uptake of organic compounds for heterotrophic growth, a metabolic mode called chemolithoheterotrophy that is not found in other symbioses. Although several symbionts have heterotrophic features to supplement primary production, in Kentron they appear to supplant it entirely.

Desulfurization of high sulfur fine coal using a novel combined beneficiation process

The throughputof high-ash and high-sulfur fine-grain coal (0–6 mm) increases year by year. The seriousproblemof direct combustion is the formation of acid rain and smog. Therefore, the pre-combustion desulfurization and ash reduction can reduce environmental pollution. A combined process of dry separation and microwave desulfurization for the cleaning of the 0–6 mm fine coal was applied. The effectsofgas velocity, vibration amplitude and frequency on the removal ofinorganic sulfurwere analyzed systematically. At the same time, the effects of additives, microwave power, irradiation time and temperature on the removal of organic sulfur in the microwave desulfurization reactorwere investigated. The results show that the compounddry separator cansorts the 0–6 mm fine coal under the optimal operating parameters (A = 3 mm, f = 22.5 Hz, v = 0.68 m3/s). After the separation, the yield, ash and sulfur contents of the pre-separatedclean coalis 63.6%, 12.4% and 4.12%, respectively.The compounddry separatorcan effectively remove mineral impurities such as inorganic sulfur. The ash is reducedapparently.However,the organic sulphide cannot be removedby the separator. Asthe pre-separatedclean coal has high sulfur content thatis mainly organic sulfide, the microwave desulfurization reactoris used to remove this part of organic sulfur. The results show that the NaOH solution additive is more beneficial to improve the microwave desulfurization. The desulfurization rate increase with the increasing of temperature and radiationtime and the irradiation time has amore obviouseffect. After the microwave desulfurization the yield, sulfur and ash contents of the clean coal are60.8%, 0.98% and 9.74%, respectively. As a result, the microwave desulfurization processcan effectively remove the organic sulfur compounds.

Abiotic formation of dissolved organic sulfur in anoxic sediments of Santa Barbara Basin

Sulfurization has been found to enhance organic matter preservation and petroleum formation in marine sediments. However, we do not yet have a comprehensive understanding of sulfurization mechanisms. In this study, we investigated several possible mechanisms of dissolved organic sulfur (DOS) formation in the top 4.5 m of anoxic sediments of Santa Barbara Basin (SBB), California Borderland. Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS), we identified chemical formulas of potential dissolved organic matter (DOM) precursors to these DOS compounds. We also examined how the formulas of abiotically formed DOS changed as a function of depth across a major redox gradient.Results show that abiotic nucleophilic addition reactions involving bisulfide (HS−) and polysulfide (HSx−) are the major sulfurization pathways that form DOS in anoxic pore waters of SBB sediments. We identified 2124 unique DOS formulas that could be generated from the addition of HS− and HSx− to 2203 DOM formulas, and this accounted for ∼70% of all DOS formulas detected in these pore waters. Examining the DOM formulas that served as reactants in the abiotic sulfurization reactions, we found that 64% contained only carbon, hydrogen, and oxygen (CHO formulas) while the remainder (34%) included nitrogen (DON formulas). Our results revealed high reactivity toward sulfurization among many of the CHO and DON formulas that have H/C and O/C elemental ratios that overlap with those of carboxyl-rich alicyclic molecules (CRAM). This specific class of formulas could play an important role in the formation of organic sulfur compounds in sulfidic marine ecosystems, and in the formation of sulfur-containing protokerogen in marine sediments. Our results further suggest that anoxic sediments are a source of DOS compounds to the oceans.

Sulfur isotopic composition of gas-phase organic sulfur compounds provides insights into the thermal maturation of organic-rich rocks

Volatile and gas phase organic sulfur compounds (VOSCs) are important components in subsurface reservoir fluids and despite their relatively low concentrations, can provide important information about organic matter origin, diagenetic transformation, thermal maturation, and oil and gas generation, expulsion, and migration. We present an approach for the utilization of VOSC concentration and compound specific S isotopes ratio (δ34S) data as a new geochemical tool to study natural gas origin and formation. We studied the formation pathways of VOSCs, their δ34S values, and interaction with an organic-rich sedimentary rock (or ‘source rock’) from the Ghareb Formation (Type II-S kerogen) deposited in an upwelling marine environment. The immature source rock was subjected to laboratory controlled thermal maturation. We used a semi-open, non-isothermal pyrolysis system heated between 200 and 440 °C, and analyzed the molecular composition and compound specific δ34S values of the evolved gases at various thermal maturity stages. Formation of VOSCs commenced at 206 °C, a temperature generally associated with less thermally mature systems, and typically before the onset of oil generation for similar organic-rich source rocks, allowing study of low thermal maturity conditions (∼0.3 %Roeq). Overall, the VOSCs obtained had δ34S values similar to the bulk kerogen values (mostly within 4‰). However, thiol (or mercaptan) δ34S values closely followed those of H2S (Δ34Sthiols-H2S = −1 ± 1‰) throughout the experiment. Ab-initio calculations for the S isotopic exchange between H2S and thiols were close to the experimental observations. This suggests that thiols rapidly attained equilibrium with H2S despite their very short residence time in the system (minutes to hours). Furthermore, throughout the experiment, the concentrations of the six different thiols were found to be proportional to the coexisting, concentration ratio of [H2]/[H2S]. The proportionality factors of the 6 different thiols strongly correlate with reported heats of formation (ΔHf°), further supporting the notion that the generation of thiols in the system rapidly reached equilibrium. At pyrolysis temperatures up to 350 °C, δ34S and concentration values of other VOSCs produced in the gas phase, including sulfides and thiophenes, probably represent generation from S-containing moieties in kerogen and bitumen with limited interaction with co-existing H2S. The reaction of hydrocarbons and H2S to produce VOSCs is inversely correlated with thermal stability, i.e. thiols > sulfides > thiophenes. Therefore, the δ34S values, concentrations and distributions of VOSCs can be utilized as a proxy for reaction extent and formation mechanism of petroleum and H2S, including primary generation by thermal maturation, or potentially other processes such as migration and thermochemical sulfate reduction. This work demonstrates a novel and useful geochemical tool to study the source and fate of natural gas in the subsurface.

Synthesis and Characterization of New Inorganic‐Organic Hybrid Nanocomposite PMo11Cu@MgCu2O4@CS as an Efficient Heterogeneous Nanocatalyst for ODS of Real Fuel

AbstractIn this work, a new nanocomposite (PMo11Cu@MgCu2O4@CS) was synthesized by reaction of copperII‐monosubstituted phosphomolybdate (PMo11Cu), magnesiocopperite (MgCu2O4) and Chitosan (CS) via the sol‐gel method. The assembled nanocomposite was characterized by FTIR, XRD, SEM. The catalytic activity of the nanocomposite was tested on oxidative desulfurization (ODS) of real gasoline in the presence of CH3COOH/H2O2 in the volume ratio of 1/2 as an oxidant. Additionally, the results were compared with the oxidation reaction of prepared model sulfur compounds at the same conditions. The ODS results showed that immobilized of PMo11Cu on the CS and MgCu2O4 nanoceramic increased the efficiency and activity of the PMo11Cu in the removal of organic sulfur compounds (OSCs). The PMo11Cu@CS @MgCu2O4 could be reused for at least five times without notable reduction in efficiency of ODS system. This investigation presents a promising approach to the efficient removal of OSCs from gasoline using PMo11Cu@MgCu2O4@CS catalyst under mild reaction conditions.

Depositional and diagenetic constraints on the abundance and spatial variability of carbonate-associated sulfate

Marine carbonate rocks are composed, in varying abundance, of cement, micrite, abiotic grains and fossils, which can provide information about the physical and chemical environments in which they formed. Geochemical analyses of these carbonates are not always interpreted alongside the wealth of geologic (including petrographic) information available, resulting in potentially faulty reconstructions of biogeochemical and environmental conditions. These concerns have prompted closer scrutiny of the effect of depositional lithofacies and diagenesis on carbonate proxies. Here, we have combined X-ray Absorption Near Edge Structure (XANES) spectroscopy and μ-X-ray Fluorescence (μ-XRF) imaging to map the speciation and abundance of sulfur in carbonate petrographic thin sections in Upper Ordovician carbonates from Anticosti Island, Canada and early Silurian carbonates from Gotland, Sweden, across multiple depositional facies. Lithofacies and fossil communities between Anticosti Island and Gotland are similar, which allows for comparison of changes in the dominant S species and their abundance in separate basins, associated with variations in (glacio)eustatic sea level. Sulfide abundance is greatest in mudstone, wackestone and packstone facies, where interstitial micrite hosts abundant pyrite. Sulfate abundance, as carbonate-associated sulfate (CAS), varies within individual fossil fragments, as well as within the same fossil phylum and is particularly high in unaltered brachiopods. In contrast, sulfate abundance is generally very low in micrite (near the detection limit) and generally arises in situ from sulfide that has been oxidized as opposed to true CAS. In different cement fabrics, sulfate abundance is greatest in drusy, pore-filling cements. Organic sulfur compounds are also detected and, although low in abundance, are mostly found within micrite. The detection and characterization of both inorganic sulfur and organic sulfur compounds provides a platform to understand early processes of biomineralization. This approach will broaden our understanding of the source of inorganically bound sulfate in ancient carbonates, as well as the effect of depositional setting and diagenesis on CAS incorporation, (re)mobilization, and ultimate abundance in sedimentary carbonates. Additionally, this work has implications for the CAS isotopic value of individual carbonate components that may affect interpretations of stratigraphic variability of numerous CAS sections throughout Earth history.

Identification of Proteins and Genes Expressed by Methylophaga thiooxydans During Growth on Dimethylsulfide and Their Presence in Other Members of the Genus.

Dimethylsulfide is a volatile organic sulfur compound that provides the largest input of biogenic sulfur from the oceans to the atmosphere, and thence back to land, constituting an important link in the global sulfur cycle. Microorganisms degrading DMS affect fluxes of DMS in the environment, but the underlying metabolic pathways are still poorly understood. Methylophaga thiooxydans is a marine methylotrophic bacterium capable of growth on DMS as sole source of carbon and energy. Using proteomics and transcriptomics we identified genes expressed during growth on dimethylsulfide and methanol to refine our knowledge of the metabolic pathways that are involved in DMS and methanol degradation in this strain. Amongst the most highly expressed genes on DMS were the two methanethiol oxidases driving the oxidation of this reactive and toxic intermediate of DMS metabolism. Growth on DMS also increased expression of the enzymes of the tetrahydrofolate linked pathway of formaldehyde oxidation, in addition to the tetrahydromethanopterin linked pathway. Key enzymes of the inorganic sulfur oxidation pathway included flavocytochrome c sulfide dehydrogenase, sulfide quinone oxidoreductase, and persulfide dioxygenases. A sulP permease was also expressed during growth on DMS. Proteomics and transcriptomics also identified a number of highly expressed proteins and gene products whose function is currently not understood. As the identity of some enzymes of organic and inorganic sulfur metabolism previously detected in Methylophaga has not been characterized at the genetic level yet, highly expressed uncharacterized genes provide new targets for further biochemical and genetic analysis. A pan-genome analysis of six available Methylophaga genomes showed that only two of the six investigated strains, M. thiooxydans and M. sulfidovorans have the gene encoding methanethiol oxidase, suggesting that growth on methylated sulfur compounds of M. aminisulfidivorans is likely to involve different enzymes and metabolic intermediates. Hence, the pathways of DMS-utilization and subsequent C1 and sulfur oxidation are not conserved across Methylophaga isolates that degrade methylated sulfur compounds.

Diversity of Dimethylsulfoniopropionate Degradation Genes Reveals the Significance of Marine Roseobacter Clade in Sulfur Metabolism in Coastal Areas of Antarctic Maxwell Bay.

Dimethylsulfoniopropionate (DMSP) is an organic sulfur compound that occurs in large amounts in oceans around the world, and it plays an important role in the global sulfur cycle. DMSP released into seawater can be rapidly catabolized by bacteria via two pathways, namely, demethylation or cleavage pathway. Members of the Roseobacter clade frequently possess enzymes involved in the DMSP demethylation or cleavage pathway. We tried to measure the diversity of genes encoding DMSP demethylase (dmdA) and DMSP lyases (dddD, dddL, and dddP) in bacteria in the surface seawater of Ardley Cove and Great Wall Cove in Antarctic Maxwell Bay using DMSP degradation gene clone library analysis. Although we did not detect sequences related to the dddD or dddL gene, both bacterial dmdA and dddP genes found in the two coves were completely confined to the Roseobacter clade, which indicated that this clade plays a significant role in DMSP catabolism in the coastal seawaters of Maxwell Bay. In addition, compared with bacterial DMSP degradation genes in Arctic coastal seawater, our results suggest that both bipolar and endemic bacterial DMSP degradation genes exist in polar marine environments. The findings of this study improve our knowledge of the distribution of DMSP degradation genes in polar marine ecosystems.

Diamondoids as tracers of late gas charge in oil reservoirs: Example from the Tazhong area, Tarim Basin, China

Significant petroleum resources occur in the Ordovician carbonate reservoirs of the Tazhong area (Tarim Basin, China) in accumulations of black oil, volatile oil and condensate. However, the factors controlling the distribution of pools with different fluid phases remain poorly understood. Here, we integrate geological and conventional oil/gas geochemical data with an extensive dataset on diamondoids and propose a model for the occurrence of petroleum fluids in the area. Oils in the study area contain low variety and concentration of diamondoids and organic-sulfur compounds (OSCs) and have oil-dissolved wet gas mostly co-generated with oil. In contrast, liquids in the condensate reservoirs are significantly enriched in various types of diamondoids and OSCs, and have dry associated gas with methane enriched in 13C and relatively high content of H2S. We interpret that mature gas from deeper Cambrian strata, likely generated from thermally cracked oils and affected by thermochemical sulfate reduction (TSR), invaded the condensate reservoirs. Black oil reservoirs did not receive this late gas charge and this preserved their oil phase. The 1D burial history models and data on fluid inclusions suggest that oil charged all studied Ordovician reservoirs in the Late Permian – Triassic time, while the late gas charge occurred in selected reservoirs in the Late Himalayan time (∼10 Ma). Diamondoids proved to be useful indicators of the late gas charge as their variety and concentrations in liquids from the study area show good correlation with the extent of gas invasion.

Corrosion inhibition of carbon steel in diethanolamine–H2O–CO2 system by some organic sulphur compounds

ABSTRACTThis paper presents an electrochemical investigation of the corrosion inhibition of carbon steel in diethanolamine–water–carbon dioxide systems by four sulphur-containing organic compounds: 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, diethyl thiourea and dimethyl sulfoxide which were found to be effective in the same order as introduced. Potentiodynamic polarisation revealed their cathodic mechanism of action. The adsorption–desorption behaviour of the inhibitors was studied using capacitance-potential and the constant phase element exponent-potential profiles obtained from dynamic electrochemical impedance spectroscopy measurements. Furthermore, quantum chemical calculations at the density functional theory level were performed to help in the analysis of the experimental results. The inhibition power of mercaptobenzazoles was found regardless to whether they were dissociated or not. The double layer capacitance values showed a rather consistent increasing trend with some theoretical parameters namely, the fraction of transferred electrons, the highest occupied molecular orbital energy level, and the permanent dipole moments of the inhibitor molecules.

An internal oxidant-directing strategy enabling transition metal-free C–S bond ligation

Organic sulfur compounds have broad applications in biology, medicine and material sciences and intensive efforts have been devoted to developing mild and general C–S bond-forming methods. However, a mild, transition-metal-free, direct C–H bond functionalization method remains elusive. Here, we report the use of an internal oxidant-directing strategy to achieve this goal. The cascade reactions described here show excellent chemoselectivity and a wide substrate scope for both oxyamines and sulfenylation reagents. This study enlarges the synthesis toolbox for preparing structurally diverse sulfilimines under mild conditions.

Control of Bacterial Sulfite Detoxification by Conserved and Species-Specific Regulatory Circuits.

Although sulfite, a by-product of the degradation of many sulfur compounds, is highly reactive and can cause damage to DNA, proteins and lipids, comparatively little is known about the regulation of sulfite-oxidizing enzyme (SOEs) expression. Here we have investigated the regulation of SOE-encoding genes in two species of α-Proteobacteria, Sinorhizobium meliloti and Starkeya novella, that degrade organo- and inorganic sulfur compounds, respectively, and contain unrelated types of SOEs that show different expression patterns. Our work revealed that in both cases, the molecular signal that triggers SOE gene expression is sulfite, and strong up-regulation depends on the presence of a sulfite-responsive, cognate Extracytoplasmic function (ECF) sigma factor, making sulfite oxidation a bacterial stress response. An additional RpoE1-like ECF sigma factor was also involved in the regulation, but was activated by different molecular signals, taurine (Sm) and tetrathionate (Sn), respectively, targeted different gene promoters, and also differed in the magnitude of the response generated. We therefore propose that RpoE1 is a secondary, species-specific regulator of SOE gene expression rather than a general, conserved regulatory circuit. Sulfite produced by major dissimilatory processes appeared to be the trigger for SOE gene expression in both species, as we were unable to find evidence for an increase of SOE activity in stationary growth phase. The basic regulation of bacterial sulfite oxidation by cognate ECF sigma factors is likely to be applicable to three groups of alpha and beta-Proteobacteria in which we identified similar SOE operon structures.

Insight Into Interactions of Thermoacidophilic Archaea With Elemental Sulfur: Biofilm Dynamics and EPS Analysis.

Biooxidation of reduced inorganic sulfur compounds (RISCs) by thermoacidophiles is of particular interest for the biomining industry and for environmental issues, e.g., formation of acid mine drainage (AMD). Up to now, interfacial interactions of acidophiles with elemental sulfur as well as the mechanisms of sulfur oxidation by acidophiles, especially thermoacidophiles, are not yet fully clear. This work focused on how a crenarchaeal isolate Acidianus sp. DSM 29099 interacts with elemental sulfur. Analysis by Confocal laser scanning microscopy (CLSM) and Atomic force microscopy (AFM) in combination with Epifluorescence microscopy (EFM) shows that biofilms on elemental sulfur are characterized by single colonies and a monolayer in first stage and later on 3-D structures with a diameter of up to 100 μm. The analysis of extracellular polymeric substances (EPS) by a non-destructive lectin approach (fluorescence lectin-barcoding analysis) using several fluorochromes shows that intial attachment was featured by footprints rich in biofilm cells that were embedded in an EPS matrix consisting of various glycoconjugates. Wet chemistry data indicate that carbohydrates, proteins, lipids and uronic acids are the main components. Attenuated reflectance (ATR)-Fourier transformation infrared spectroscopy (FTIR) and high-performance anion exchange chromatography with pulsed amperometric detection (HPAE-PAD) indicate glucose and mannose as the main monosaccharides in EPS polysaccharides. EPS composition as well as sugar types in EPS vary according to substrate (sulfur or tetrathionate) and lifestyle (biofilms and planktonic cells). This study provides information on the building blocks/make up as well as dynamics of biofilms of thermoacidophilic archaea in extremely acidic environments.

Methanethiol and Dimethylsulfide Cycling in Stiffkey Saltmarsh.

Methanethiol (MeSH) and dimethylsulfide (DMS) are volatile organic sulfur compounds (VOSCs) with important roles in sulfur cycling, signaling and atmospheric chemistry. DMS can be produced from MeSH through a reaction mediated by the methyltransferase MddA. The mddA gene is present in terrestrial and marine metagenomes, being most abundant in soil environments. The substrate for MddA, MeSH, can also be oxidized by bacteria with the MeSH oxidase (MTO) enzyme, encoded by the mtoX gene, found in marine, freshwater and soil metagenomes. Methanethiol-dependent DMS production (Mdd) pathways have been shown to function in soil and marine sediments, but have not been characterized in detail in the latter environments. In addition, few molecular studies have been conducted on MeSH consumption in the environment. Here, we performed process measurements to confirm that Mdd-dependent and Mdd-independent MeSH consumption pathways are active in tested surface saltmarsh sediment when MeSH is available. We noted that appreciable natural Mdd-independent MeSH and DMS consumption processes masked Mdd activity. 16S rRNA gene amplicon sequencing and metagenomics data showed that Methylophaga, a bacterial genus known to catabolise DMS and MeSH, was enriched by the presence of MeSH. Moreover, some MeSH and/or DMS-degrading bacteria isolated from this marine environment lacked known DMS and/or MeSH cycling genes and can be used as model organisms to potentially identify novel genes in these pathways. Thus, we are likely vastly underestimating the abundance of MeSH and DMS degraders in these marine sediment environments. The future discovery and characterization of novel enzymes involved in MeSH and/or DMS cycling is essential to better assess the role and contribution of microbes to global organosulfur cycling.

New coulometeric method for determination of the chemical compositions of refinery waste

Organic sulfur compounds are natural components of crude oil. The presence of these compounds is undesirable, as they cause corrosion of equipment and contaminate the atmosphere during combustion. Sulfur compounds ruin expensive catalysts and release sulfur oxides into the atmosphere when burned, thereby creating environmental problems. Therefore, modern methods are needed to detect, identify and measure the concentrations of sulfur contents, water, and other elements in petroleum products. This work proposed a method for the quantitative analysis of petroleum and petroleum waste, including refinery sludges, based on the coulometry method The present article describes the methods to determine the total amount of sulfur in the waste oil and the number of hydrocarbons in the viscous oil wastes. Additionally, Karl- Fischer method was adapted to measure the content of water in crude oil. In our work reported here, a titration coulometric reagent administration and potentiometric detection using ion-selective electrodes has been worked out and applied for the determination of sulfur and water concentration in crude oil samples.

Polyoxometalate as an effective catalyst for the oxidative desulfurization of liquid fuels: a critical review

Abstract In order to meet the stringent environmental and industrial legislation on fuel specifications, sulfur compounds have to be removed efficiently from fuels. The requirement to produce ultralow-sulfur fuels (S < 10 ppm) has stimulated many works in the area of conventional hydro-desulfurization (HDS) method. Oxidative desulfurization (ODS), as an alternative or complementary technology to HDS for deep desulfurization, is conducted with high selectivity and reactivity to sterically hindered S compounds under mild reaction conditions. In the ODS process, using an appropriate oxidant in the presence of a catalyst, organic sulfur compounds can be oxidized selectively to their corresponding sulfoxides and sulfones, which can be easily removed by different separation methods. Having great catalytic characteristics, polyoxometalate materials have been utilized as a vital class of catalysts for deep desulfurization of fuels. In the past few decades, ODS of fuels using polyoxometalate as catalyst has drawn much attention, and various studies have been carried out in this area. Here, we give a critical review for the removal of sulfur compounds from liquid fuels (mostly from diesel and model fuels) by ODS via homogeneous and heterogeneous polyoxometalate catalysts.

Altered Non‐Coding RNA‐Histone Acetylation Regulatory Circuit Is Associated With Cognitive Impairment via Gut Dysbiosis in Aging Mice

Advancing age is the top risk factor for the development of neurodegenerative disorders such as Alzheimer's Disease (AD). However, the contribution of the aging process to Alzheimer's disease (AD) pathology remain unclear. It is also unclear, whether age‐related disruption of the gut‐barrier integrity or dysbiosis causes impaired hippocampal memory. Allyl sulfide (AS), an organic sulfur compound in garlic, has many health benefits and is known for its detoxifying agents. However, the precise role of allyl sulfide in regulating hippocampal memory function at mechanistic levels in mice still needs to be investigated. Here we show that memory disturbances with altered hippocampal chromatin plasticity in the aging brain of the mouse are associated with gut‐microbiota changes and intragastric administration of allyl sulfide retards age‐related defects. To test the hypothesis, we employed 4‐months age‐matched male wild‐type C57BJ/L6 (WT) mice as control group (Young), 24‐months old age‐matched male WT mice group as aging group (AG) and another 24‐months old age‐matched male WT mice group received daily AS at the dosage of 2mg/kg/b.wt through oral gavage (AG+AS). The results show that Young and AG+AS mice showed higher behavioral proficiency and more robust long‐term and short‐term memory compared to AG mice. Gut microbiota is significantly altered as assessed by the denaturing gradient gel electrophoresis (DGGE) analysis in AG group in compared with Young and AG+AS group. The mechanistic study shows that AG mice display an increased plasma level of circulating non‐coding RNA‐Hotair (lncRNA‐Hotair), as assessed by RT2 lncRNA qPCR Assay. To test whether memory impairment correlates with altered hippocampal chromatin plasticity in a lncRNA‐Hotair dependent manner, we first investigated the hippocampal histone acetylation pattern in the AG group. The data suggest that lncRNA‐Hotair causes a specific deregulation of histone H3 lysine 27 (H3K27) acetylation (ac) at the neuronal derived natriuretic factor (NDNF) promoter of hippocampal tissue of AG group and, therefore, fail to initiate a hippocampal gene transcription associated with memory consolidation. However, administration of AS in the AG group could ameliorate gut dysbiosis and memory functions. In lncRNA‐Hotair‐deficient mice, which are protected from age‐related microbiota changes and memory impairment. Furthermore, restoration of NDNF using recombinant NDNF‐therapy reinstates to the recovery of cognitive abilities. In conclusion, our data suggest that lncRNA‐Hotair upregulation and H3K27ac regulatory activity may represent an early biomarker in the aging mouse brain. In addition, AS could serve as potential anti‐aging therapeutics in treating aging individuals.Support or Funding InformationThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.