Organic Sulfur Compounds Research Articles

Alternate routes to sustainable energy recovery from fossil fuels reservoirs. Part 1. Investigation of high-temperature reactions between sulfur oxy anions and crude oil

The world is undergoing a substantial transition in its energy supply. Examining the possibilities to recover and use fossil fuel energy without emitting carbon dioxide to the surface, H2S was considered as an alternative energy vector to deliver a carbon free fuel from petroleum reservoirs to the surface. In this study, we investigated the high P-T chemical oxidation of crude oil with a suite of inorganic sulfur compounds. Tested inorganic sulfur compounds can be ordered by their ability to promote chemical changes to the oil matrix with the concomitant production of hydrogen sulfide, with a reactivity series, listed in order of decreasing reactivity as: S0 > S2O32− ~ S4O62− > SO32− > SO42−. The reaction mechanisms proposed in the study also light on likely key intermediate reactants and the geological timescale process of thermochemical sulfate reduction. Polysulfide species (containing S-S bond structures), such as thiosulfate and tetrathionate, may be reactive intermediates during the redox reaction. However, the early stage of thermochemical sulfate reduction may also involve labile organic sulfur functional groups converting to more stable molecules with aromatic structural units, such as dibenzothiophenes (DBT) and benzonaphthothiophenes (BNT). The apparent formation of saturated fatty acids and O2, NO and NO2 aromatic heteroatom species indicates the oxidation of saturated and aromatic hydrocarbons or heteroatom compounds. The oxidation of aromatic species may lead to aromatic ring-opening, followed by decarboxylation forming CO2 as final products.

TSR-derived hydrogen sulfide and organic sulfur compounds: New insights from chemical thermodynamic investigation

Thermochemical sulfate reduction (TSR) is conventionally defined as an organic – inorganic interaction between sulfates and hydrocarbons occurring at ≥100 °C in deep buried geologic settings. In this paper, reactivity of various hydrocarbons, sulfate contact ion-pairs (CIP) and inorganic matters, as well as possible formation mechanisms of TSR-derived organic sulfur compounds (OSCs) were evaluated respectively from chemical thermodynamic perspectives. At the same burial temperature, the oxidizability order of the seven sulfate contact ion-pairs for CH4 is thermodynamically determined as [Al2(SO4)3]CIP ≫ [MgSO4]CIP > [FeSO4] CIP > [CaSO4]CIP > [SrSO4]CIP > [BaSO4]CIP > [Na2SO4]CIP. NH4+, hydrogen gas and pyrobitumen derived from thermal cracking were also most likely involved in TSR as well as hydrocarbons. Thereinto, TSR by NH4+ might provide an alternative origin of N2 in sedimentary environments in addition to conventional origins of N2. Although it is thermodynamically feasible for thiols or thiophenes generation from three possible pathways, i.e., H2S–alkanes, H2S–olefins and S0–alkanes, most of OSCs in TSR zones are more likely derived from H2S–alkanes interactions in view of low abundance of elemental sulfur and/or olefins relative to that of H2S and alkanes in TSR-altered oil and gas reservoirs. The likelihood of formation of OSCs involving methane cannot be entirely excluded.

Intracellular Sulfur Inclusions: Source of Energy or Heater?

There are various groups of bacteria which receive energy from oxidation of inorganic sulfur compounds. Some of them produce elemental sulfur as an intermediate product and deposit it outside their cells. The group "sulfur bacteria" was described by their ability to produce intracellular sulfur inclusions. Traditionally, calculations of the released energy considered effect of the bacterial sulfide oxidation but never considered energy of the S-polymerization from monoatomic S to 8 atoms ring which is also essential (262.9kJ). Till present, no biochemical reactions are known which could use energy of this eight atoms ring formation process. Thus, it is proposed that the intracellular sulfur inclusions can provide a lasting heating content of the cells as an additional advantage for the sulfur bacteria.

AL – Mansuriya gas fields associated liquid and its role to increase the potential capacity of gasoline fuel in Daura oil refinery

Hydrotreating processing is commonly used to remove platforming catalyst poisons from straight run or cracked naphthas prior to charging to the platforming Process unit. It can be seen that the primary function of the naphtha Hydrotreating Process can be characterized as a “Clean up” Operation. The catalyst used in the Naphtha Hydrotreating Process is composed of an alumina base impregnated with compounds of cobalt or nickel and molybdenum. The catalyst is insensitive to most poisons which affect dehydrogenation reactions. A relatively high percentage of carbon on the catalyst does not materially affect its sensitivity or selectivity. Volumetric recoveries of products depend on the sulfur and olefin contents [1].
 The Naphtha Hydrotreating Process is a catalytic refining process employing a selected catalyst and a hydrogen-rich gas stream to decompose organic sulfur, oxygen and nitrogen compounds contained in hydrocarbon fractions. In addition, hydrotreating removes organo-metallic compounds and saturates olefinic compounds.
 Organo-metallic compounds, notably arsenic and lead compounds, are known to be permanent poisons to platinum catalysts. "The complete removal of these materials by Hydrotreating processing gives longer catalyst life in the platforming unit.
 Sulfur, above a critical level, is a temporary poison to platforming catalysts and causes an unfavorable change in the product distribution. Organic nitrogen is also a temporary poison to platforming catalyst. It is an extremely potent one, however, and relatively small amounts of nitrogen compounds in the Platformer feed can cause large deactivation effects, as well as the deposition of ammonium chloride salts in the platforming unit cold sections.
 Oxygen compounds are detrimental to the operation of a Platformer. Any oxygen compounds which are not removed in the hydrotreater will be converted to water in the platforming unit, thus affecting the water/ chloride balance of the platforming catalyst. Large amounts of olefins contribute to increase coking of the platforming catalyst. Also, olefins can poly­merize at platforming operating conditions which can result in exchanger and reactor fouling.
 The Naphtha Hydrotreating Process makes a major contribution to the ease of operation and economy of platforming. Much greater flexibility is afforded in choice of allowable charge stocks to the platforming unit. Because this unit protects the platforming catalyst, it is important to maintain consistently good operation in the Hydrotreating Unit.
 In addition to treating naphtha for Platformer feed, naphthas produced from thermal cracking processes, such as delayed coking and visbreaking, are usually high in olefinic content and other contaminants, and may not be stable in storage. These naphthas may be hydrotreated to stabilize the olefins and to remove organic or metallic contaminants, thus providing a marketable product.

A New Approach to the Assessment of the Safety of Tea, Coffee, Cocoa, and Vegetable Oils, Based on the Rapid Screening of Samples for the Total Concentration of Fluorine-, Chlorine-, and Bromine-Containing Organic Compounds

We propose a new approach to assessing the contamination of tea, coffee, cocoa, and vegetable oils with F-, Cl-, Br- and S-containing organic pesticides and other hazardous anthropogenic and natural compounds at a trace level. The approach ensures the rapid screening of test samples for the total concentration of all halogen and sulfur organic compounds present in the samples. Sample preparation is excluded. The procedure is based on the direct high-temperature oxidative conversion of a test sample under oxygen; the absorption of inorganic salts present in the sample in a reactor; the absorption of the conversion products of organic compounds of the sample, including the analyzed ones, by deionized water with the formation of F–, Cl–, Br– and SO $$_{4}^{{2 - }}$$ anions; and their determination in the absorbate by ion chromatography. This approach ensures the simultaneously reliable determination of all volatile, medium-volatile, and nonvolatile organohalogen and organosulfur compounds present in one sample and, thereby, improves the reliability of detection by eliminating their losses during the analysis.

Reaction of DMS and HOBr as a Sink for Marine DMS and an Inhibitor of Bromoform Formation

Recently, we suggested that hypobromous acid (HOBr) is a sink for the marine volatile organic sulfur compound dimethyl sulfide (DMS). However, HOBr is also known to react with reactive moieties of dissolved organic matter (DOM) such as phenolic compounds to form bromoform (CHBr3) and other brominated compounds. The reaction between HOBr and DMS may thus compete with the reaction between HOBr and DOM. To study this potential competition, kinetic batch and diffusion-reactor experiments with DMS, HOBr, and DOM were performed. Based on the reaction kinetics, we modeled concentrations of DMS, HOBr, and CHBr3 during typical algal bloom fluxes of DMS and HOBr (10-13 to 10-9 M s-1). For an intermediate to high HOBr flux (≥10-11 M s-1) and a DMS flux ≤10-11 M s-1, the model shows that the DMS degradation by HOBr was higher than for photochemical oxidation, biological consumption, and sea-air gas exchange combined. For HOBr fluxes ≤10-11 M s-1 and a DMS flux of 10-11 M s-1, our model shows that CHBr3 decreases by 86% compared to a lower DMS flux of 10-12 M s-1. Therefore, the reaction between HOBr and DMS likely not only presents a sink for DMS but also may lead to suppressed CHBr3 formation.

Investigating the souring mechanism in two giant carbonate oil reservoirs, southwestern Iran

In general, a hydrocarbon reservoir with a produced gas stream having more than three parts per million by volume (ppmv) of hydrogen sulfide is considered a sour reservoir. This study aims to present novel ideas on the main souring mechanisms in Bangestan Group, a well-known Mid-Cretaceous hydrocarbon hosting carbonate in Iran, including Ilam, Sarvak, and Kazhdumi formations. Especially, several scenarios are discussed on potential source of H2S in Sarvak Formation and controversial sweetness of the Upper Ilam Reservoir. At first, both of the bacterial or microbial sulfate Reduction (BSR or MSR) and thermochemical sulfate reduction (TSR) mechanisms were rejected based on the reported bottom-hole temperature and lack of anhydrite in rock matrix, respectively. Moreover, the possibility of souring due to migration was disregarded mainly due to the reported constant concentration of H2S over time and among the target oilfield. At the end, thermal decomposition of organic sulfur compounds within the kerogen or crude oil was introduced as the only potential souring mechanism that was further proven through sulfur isotopic analysis. Furthermore, the possibility of H2S absorption in lower horizons of Ilam Formation, and so sweetness of this formation, due to the presence of ferrous minerals was evidenced through detailed petrographic analysis.

Genome-scale metabolic model of the diatom Thalassiosira pseudonana highlights the importance of nitrogen and sulfur metabolism in redox balance

Diatoms are unicellular photosynthetic algae known to secrete organic matter that fuels secondary production in the ocean, though our knowledge of how their physiology impacts the composition of dissolved organic matter remains limited. Like all photosynthetic organisms, their use of light for energy and reducing power creates the challenge of avoiding cellular damage. To better understand the interplay between redox balance and organic matter secretion, we reconstructed a genome-scale metabolic model of Thalassiosira pseudonana strain CCMP 1335, a model for diatom molecular biology and physiology, with a 60-year history of studies. The model simulates the metabolic activities of 1,432 genes via a network of 2,792 metabolites produced through 6,079 reactions distributed across six subcellular compartments. Growth was simulated under different steady-state light conditions (5–200 μmol photons m-2 s-1) and in a batch culture progressing from exponential growth to nitrate-limitation and nitrogen-starvation. We used the model to examine the dissipation of reductants generated through light-dependent processes and found that when available, nitrate assimilation is an important means of dissipating reductants in the plastid; under nitrate-limiting conditions, sulfate assimilation plays a similar role. The use of either nitrate or sulfate uptake to balance redox reactions leads to the secretion of distinct organic nitrogen and sulfur compounds. Such compounds can be accessed by bacteria in the surface ocean. The model of the diatom Thalassiosira pseudonana provides a mechanistic explanation for the production of ecologically and climatologically relevant compounds that may serve as the basis for intricate, cross-kingdom microbial networks. Diatom metabolism has an important influence on global biogeochemistry; metabolic models of marine microorganisms link genes to ecosystems and may be key to integrating molecular data with models of ocean biogeochemistry.

Recent Advances in Multicomponent Reactions with Organic and Inorganic Sulfur Compounds.

In recent years, multicomponent reactions with inorganic and organic sulfur compounds as one of reactants have achieved a remarkable development. In this review, we summarize recent advances in the multicomponent reactions involving sulfur components, which include elemental sulfur, sodium metabisulfite, sodium hyposulfite, potassium pyrosulfite, DABSO, sodium sulfide, thiocyanate, sulfur dioxide, carbon disulfide and other divalent, tetravalent and hexavalent organosulfur compounds.

Determination of organic sulfur markers in crude oils by gas chromatography triple quadrupole mass spectrometry

Organic sulfur compounds, such as benzothiophene and dibenzothiophene, are present in crude oils, and specific isomers of these classes are known to be geochemical markers of maturity, lithology and biodegradation. Thus, knowledge of the individual concentrations of these target molecules enables us to characterize petroleum basins for better exploration. In this work, a simple and effective gas chromatography–triple quadrupole mass spectrometry method without preliminary fractionation was developed and validated for the determination of 14 organic sulfur compounds assumed to be geochemical markers for crude oils. The research was focused on the optimization of a highly selective GC-based analytical strategy using triple quadrupole MS in multiple reaction monitoring. Sample preparation was carried out by simple dilution in DCM. The method was validated, and the following parameters were expressed in terms of intraday precision: linearity, limit of detection, accuracy and precision. The limit of detection ranged from 0.005 μg mL−1 (benzothiophene) to 0.159 μg mL−1 (benzonaphthothiophene). Intraday assay precision was lower than 20% in all cases. Recoveries ranged from 78.2% (1,4-dimethyldibenzothiophene) to 117% (2,4,7-trimethyldibenzothiophene). After validation, the procedure was successfully applied to the determination of S-markers in 8 crude oil samples, and the method was determined to be precise, accurate, and suitable. Diagnostic ratios based on benzothiophenes to dibenzothiphenes were applied as tools to evaluate maturity, biodegradation and depositional ambient conditions. A cross-plot of methyldibenzothiophene versus dimethyldibenzophene ratio was utilized to classify oils according to their maturity.

Geochemical Characteristics and the Origin of Superdeep Condensates in Tarim Basin, China.

A series of trace compounds (diamondoids, ethanodiamondoids, and thiadiamondoids) were detected through two-dimensional gas chromatography/time-of-flight mass spectrometry (GC × GC-TOFMS) analysis of Ordovician condensate samples from the Tazhong area. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the biomarker parameters are less effective for high-maturity oils. Carbon isotope and geochemical features suggested that the gas is a high-temperature cracking gas when its temperature is higher than 170 °C. The H2S content is 8.27%, suggesting that it is affected by thermochemical sulfate reduction (TSR). However, the geological analysis indicated that the Ordovician reservoirs do not satisfy the conditions for TSR. The high-maturity oil in the Ordovician reservoirs may generate diamondoids and ethanodiamondoids when cracking, while TSR and severe cracking occur in deep Cambrian source rocks and produce a large number of diamondoids, ethanodiamondoids, organic sulfur compounds (OSCs), etc. The secondary geochemical products that are carried up by the dry gas and migrate upward through faults and are enriched in Ordovician crude oil reservoirs. On this basis, we proposed that the condensate presented was formed by the mixing of dry gas from Cambrian oil that was altered by cracking and TSR into Ordovician in situ slightly cracked oil, therefore speculating that the favorable reservoir–seal assemblages in this area may contain abundant oil and gas resources. Consequently, improved knowledge of secondary alteration effects on the reservoir and underground fluids is vital for oil and gas prediction and exploration development in the next step.

Allicin, the Odor of Freshly Crushed Garlic: A Review of Recent Progress in Understanding Allicin's Effects on Cells.

The volatile organic sulfur compound allicin (diallyl thiosulfinate) is produced as a defense substance when garlic (Allium sativum) tissues are damaged, for example by the activities of pathogens or pests. Allicin gives crushed garlic its characteristic odor, is membrane permeable and readily taken up by exposed cells. It is a reactive thiol-trapping sulfur compound that S-thioallylates accessible cysteine residues in proteins and low molecular weight thiols including the cellular redox buffer glutathione (GSH) in eukaryotes and Gram-negative bacteria, as well as bacillithiol (BSH) in Gram-positive firmicutes. Allicin shows dose-dependent antimicrobial activity. At higher doses in eukaryotes allicin can induce apoptosis or necrosis, whereas lower, biocompatible amounts can modulate the activity of redox-sensitive proteins and affect cellular signaling. This review summarizes our current knowledge of how bacterial and eukaryotic cells are specifically affected by, and respond to, allicin.

Ultra-deep adsorptive removal over hierarchically structured AgCeY zeolite from model gasoline with high competitor content

Metal-ion-exchanged Y zeolites are a promising adsorptive desufurization (ADS) adsorbent. However, the ADS performance is inhibited significantly by diffusion limitations of sulfur compounds in micropores, especially when refractory sulfur compounds are present in fuels. The aim of this work was to develop a novel highly active, hierarchically structured bimetal Y zeolite and to evaluate the role of mesopores on the ADS performance from fuel oils that contained large amounts of competitors. A mesoporosity was introduced in the NaY by a top-down approach (sequential dealumination–desilication). A hierarchically structured zeolite meso-AgCeY was synthesized by introducing metals, Ag and Ce, by liquid-phase ion-exchange. The prepared meso-AgCeY was characterized and evaluated in terms of ADS performance using gasolines that contained different-sized sulfides and different amounts of toluene or cyclohexene. The adsorption strength was determined by the isosteric heat of adsorption calculations. The mesopores centered around 4–30 nm was obtained for meso-AgCeY, with the preservation of the original zeolite structure. Mesopore introduction suppressed the diffusion limitation of sulfur compounds effectively. In addition, transition metal Ag and rare earth metal Ce cations, which can bind organic sulfur compounds through π-complexation and sulfur-metal interaction, respectively, provided the meso-AgCeY with a high ADS performance. The meso-AgCeY showed a thiophene ADS capacity of 4.4 or 4.1 times more than that of microporous AgCeY for gasolines that contained large amounts of toluene or cyclohexene, respectively. This result may occur because of the suppression of the non-selective molecule adsorption, improvement in mass transfer, full use of active metal sites and strong adsorption energy related with the mesopore introduction. The meso-AgCeY, which combined multiple adsorption metal ions and modified Y zeolite with mesopores, is a promising ADS adsorbent.

Sulfate transport mutants affect hydrogen sulfide and sulfite production during alcoholic fermentation.

Hydrogen sulfide is a common wine fault, with a rotten-egg odour, which is directly related to yeast metabolism in response to nitrogen and sulfur availability. In grape juice, sulfate is the most abundant inorganic sulfur compound, which is taken up by yeast through two high-affinity sulfate transporters, Sul1p and Sul2p, and a low affinity transporter, Soa1p. Sulfate contributes to H2 S production under nitrogen limitation, by being reduced via the Sulfur Assimilation Pathway (SAP). Therefore, yeast strains with limited H2 S are highly desirable. We report on the use of toxic analogues of sulfate following ethyl methane sulfate treatment, to isolate six wine yeast mutants that produce no or reduced H2 S and SO2 during fermentation in synthetic and natural juice. Four amino acid substitutions (A99V, G380R, N588K and E856K) in Sul1p were found in all strains except D25-1 which had heterozygous alleles. Two changes were also identified in Sul2p (L268S and A470T). The Sul1p (G380R) and Sul2p (A470T) mutations were chosen for further investigation as these residues are conserved amongst SLC26 membrane proteins (including sulfate permeases). The mutations were introduced into EC1118 using Crispr cas9 technology and shown to reduce accumulation of H2 S and do not result in increased SO2 production during fermentation of model medium (chemically defined grape juice) or Riesling juice. The Sul1p (G380R) and Sul2p (A470T) mutations are newly reported as causal mutations. Our findings contribute to knowledge of the genetic basis of H2 S production as well as the potential use of these strains for winemaking and in yeast breeding programmes.

Microwave absorption properties of organic sulfur compounds in coal: application of desulfurization

ABSTRACT According to the analysis of the characteristics of coal samples, organic sulfur compounds with different structures were selected and their microwave absorption performance was observed in the range of 2.0 GHz to 8.0 GHz. The relationship between absorption performance and desulfurization efficiency was studied by the microwave desulfurization experiment. Results showed that microwave frequency change slightly affects the real part of the complex dielectric constants of organic sulfur compounds. In contrast, it had a significant effect on the imaginary part of complex dielectric constants, dielectric loss tangent, microwave penetration depth and the absorption coefficient, except for the imaginary part of complex dielectric constants and dielectric loss tangent of thiophene compounds. The polarization ability of compounds in the microwave field followed the order: thiophene > mercaptan > thioether, while the efficiencies of mercaptan and thioether for absorbing electromagnetic energy and transforming it into thermal energy were more substantial than that of thiophene. The stronger microwave absorbing performance, the higher the desulfurization rate. Mercaptan and thioether compounds were more accessible to remove than thiophene from coal by microwave radiation and chemical additives.

RNA transcript response by an Acidithiobacillus spp. mixed culture reveals adaptations to growth on arsenopyrite.

Biooxidation of gold-bearing refractory mineral ores such as arsenopyrite (FeAsS) in stirred tanks produces solutions containing highly toxic arsenic concentrations. In this study, ferrous iron and inorganic sulfur-oxidizing Acidithiobacillus strain IBUN Ppt12 most similar to Acidithiobacillus ferrianus and inorganic sulfur compound oxidizing Acidithiobacillus sp. IBUNS3 were grown in co-culture during biooxidation of refractory FeAsS. Total RNA was extracted and sequenced from the planktonic cells to reveal genes with different transcript counts involved in the response to FeAsS containing medium. The co-culture's response to arsenic release during biooxidation included the ars operon genes that were independently regulated according to the arsenopyrite concentration. Additionally, increased mRNA transcript counts were identified for transmembrane ion transport proteins, stress response mechanisms, accumulation of inorganic polyphosphates, urea catabolic processes, and tryptophan biosynthesis. Acidithiobacillus spp. RNA transcripts also included those encoding the Rus and PetI proteins involved in ferrous iron oxidation and gene clusters annotated as encoding inorganic sulfur compound metabolism enzymes. Finally, mRNA counts of genes related to DNA methylation, management of oxidative stress, chemotaxis, and motility during biooxidation were decreased compared to cells growing without mineral. The results provide insights into the adaptation of Acidithiobacillus spp. to growth during biooxidation of arsenic-bearing sulfides.

Limitations of GC-QTOF-MS Technique in Identification of Odorous Compounds from Wastewater: The Application of GC-IMS as Supplement for Odor Profiling

Odorous emissions from wastewater treatment plants (WWTPs) cause negative impacts on the surrounding areas and possible health risks on nearby residents. However, the efficient and reliable identification of WWTPs’ odorants is still challenging. In this study, odorous volatile organic compounds (VOCs) from domestic wastewater at different processing units were profiled and identified using gas chromatography-ion mobility spectrometry (GC-IMS) and gas chromatography quadrupole-time-of-flight mass spectrometry (GC-QTOF-MS). The GC-QTOF-MS results confirmed the odor contribution of sulfur organic compounds in wastewater before primary sedimentation and ruled out the significance of most of the hydrocarbons in wastewater odor. The problems in odorous compounds analysis using GC-QTOF-MS were discussed. GC-IMS was developed for visualized analysis on composition characteristics of odorants. Varied volatile compounds were detected by GC-IMS, mainly oxygen-containing VOCs including alcohols, fatty acids, aldehydes and ketones with low odor threshold values. The fingerprint plot of IMS spectra showed the variation in VOCs’ composition, indicating the changes of wastewater quality during treatment process. The GC-IMS technique may provide an efficient profiling method for the changes of inlet water and performance of treatment process at WWTPs.

Genomic evidence for sulfur intermediates as new biogeochemical hubs in a model aquatic microbial ecosystem

BackgroundThe sulfur cycle encompasses a series of complex aerobic and anaerobic transformations of S-containing molecules and plays a fundamental role in cellular and ecosystem-level processes, influencing biological carbon transfers and other biogeochemical cycles. Despite their importance, the microbial communities and metabolic pathways involved in these transformations remain poorly understood, especially for inorganic sulfur compounds of intermediate oxidation states (thiosulfate, tetrathionate, sulfite, polysulfides). Isolated and highly stratified, the extreme geochemical and environmental features of meromictic ice-capped Lake A, in the Canadian High Arctic, provided an ideal model ecosystem to resolve the distribution and metabolism of aquatic sulfur cycling microorganisms along redox and salinity gradients.ResultsApplying complementary molecular approaches, we identified sharply contrasting microbial communities and metabolic potentials among the markedly distinct water layers of Lake A, with similarities to diverse fresh, brackish and saline water microbiomes. Sulfur cycling genes were abundant at all depths and covaried with bacterial abundance. Genes for oxidative processes occurred in samples from the oxic freshwater layers, reductive reactions in the anoxic and sulfidic bottom waters and genes for both transformations at the chemocline. Up to 154 different genomic bins with potential for sulfur transformation were recovered, revealing a panoply of taxonomically diverse microorganisms with complex metabolic pathways for biogeochemical sulfur reactions. Genes for the utilization of sulfur cycle intermediates were widespread throughout the water column, co-occurring with sulfate reduction or sulfide oxidation pathways. The genomic bin composition suggested that in addition to chemical oxidation, these intermediate sulfur compounds were likely produced by the predominant sulfur chemo- and photo-oxidisers at the chemocline and by diverse microbial degraders of organic sulfur molecules.ConclusionsThe Lake A microbial ecosystem provided an ideal opportunity to identify new features of the biogeochemical sulfur cycle. Our detailed metagenomic analyses across the broad physico-chemical gradients of this permanently stratified lake extend the known diversity of microorganisms involved in sulfur transformations over a wide range of environmental conditions. The results indicate that sulfur cycle intermediates and organic sulfur molecules are major sources of electron donors and acceptors for aquatic and sedimentary microbial communities in association with the classical sulfur cycle.-hYdWkMRSgNRZXNRu4CdmLVideo abstract

Sous vide pretreatment in cooking sturgeon fish burger: Effects on physicochemical properties and sensory characteristics

SummaryThe effect of sous vide (SV) pretreatment on the physicochemical (texture, water holding capacity (WHC) and protein modifications) and sensory (appearance, odour, flavour and overall acceptability) properties of sturgeon fish burgers cooked by four common methods (steaming, baking, microwaving and frying) were investigated. The texture analysis results showed that SV combined with transglutaminase could make the structure of cooked fish burgers denser and increase the springiness (ranging from 3.60 to 4.97 mm) and chewiness (ranging from 4.50 to 9.57 N), especially in microwave‐cooked samples. In terms of sensory quality, on the one hand, SV could effectively inhibit off‐flavours from oxidation and prevents evaporative losses of flavour volatiles (nitrogen oxides, organic sulphur and aromatic compounds) during cooking. On the other hand, the overall acceptability of microwave‐cooked sample pretreated with SV was higher than that of other cooking methods, especially compared with steaming (P < 0.05). The above results indicate that it is feasible to obtain common cooked fish burgers with improved physicochemical and good sensory properties using SV pretreatment.

Garlic burn injuries- a systematic review of reported cases.

Medicinal plants have many beneficial effects on human health. Garlic (Allium sativum, Alliaceae) is one of the most famous herbal species, used for various diseases and conditions. Unfortunately, garlic is also associated with adverse effects, including cutaneous manifestations. In this review, burn injuries caused by application of raw garlic are reported. Searching through PubMed, Google Scholar and ResearchGate, a total of 32 articles with 39 patients were found. Demographics of patients, reasons for garlic use, details on garlic application, as well as description of burns and its treatment are thoroughly described and discussed. In most of the cases, garlic caused second-degree burns, although some circumstances can cause formation of necrotic tissue. Various body parts were affected, legs being most common. The chemistry of garlic is also presented, with focus on volatile organic sulfur compounds, which also seem to be responsible for burns formation. Treatment of garlic burns was mainly symptomatic, and various types of drugs were used. Although not commonly expected, garlic should be taken into consideration as causative agents of burns by treating doctors, and patients should be advised against application of fresh garlic onto skin and mucosa.