Search

Thiosulfate-driven denitrification coupled with anammox (TDDA) has garnered interest for its efficient and innovative nitrogen removal capabilities. However, the intricate dynamics of the internal microbial community and the specific characteristics of anaerobic ammonium oxidizing bacteria (AnAOB) remain incompletely understood. This study combines experimental methods with density functional theory (DFT) calculations to address these gaps. The TDDA reactor was successfully started-up with an optimal S 2 O 3 2- -S/NO 3 - -N ratio of 0.6, achieving a nitrogen removal efficiency of 89.6%. Throughout this process, the relative abundance of Candidatus Kuenenia decreased by 10.2%, while the relative abundance of Candidatus Brocadia increased by 9.6%. The elevated concentration of NO₃ - -N inhibited Candidatus Kuenenia, and simultaneously stimulated the secretion of extracellular polymers, affecting Fe uptake by Candidatus Kuenenia. To further elucidate substrate competition, molecular docking simulations and DFT calculations were employed. The binding energy, compared with the electrostatic potential energy of the protein pocket, clearly demonstrated that Nir in AnAOB has a higher affinity for the substrate (E AnAOB  = -163.2 kJ/mol vs. E SOB  = -77.7 kJ/mol). By integrating molecular dynamics insights, this study overcomes experimental limitations and deepens the understanding of the mechanisms within the TDDA system., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Calcinosis cutis affects 20-40% of patients with systemic sclerosis. This study tests the hypothesis that calcium-chelating polycarboxylic acids can induce calcium dissolution without skin toxicity or irritancy. We compared citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) to sodium thiosulfate (STS) for their ability to chelate calcium in vitro using a pharmaceutical dissolution model of calcinosis (hydroxyapatite (HAp) tablet), prior to evaluation of toxicity and irritancy in 2D in vitro skin models. Resultant data was used to predict therapeutic concentrations for application in a validated 3D skin irritation model (SkinEthic™; EpiSkin SA) and to assay maximal percutaneous absorption. Dissolution performance was further assessed via ability to dissolve a calcified matrix laid down in vitro. Pharmacological dissolution studies identified that polycarboxylic acids were superior to STS in dissolving HAp tablets. In vitro, compounds had little effect on cell numbers at concentrations of < 10 mM. When applied topically to 3D models as near-saturated solutions, chelators were not irritant nor did they impact model structure histologically. CA was the most efficient chelator of calcium salts. This study highlights polycarboxylic acids, particularly CA, as potential therapies to target calcinosis cutis: these should now be investigated in human studies., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Nitrosyl iron complexes are remarkably multifactorial pharmacological agents. These compounds have been proven to be particularly effective in treating cardiovascular and oncological diseases. We evaluated and compared the antioxidant activity of tetranitrosyl iron complexes (TNICs) with thiosulfate ligands and dinitrosyl iron complexes (DNICs) with glutathione (DNIC-GS) or phosphate (DNIC-PO 4 - ) ligands in hemoglobin-containing systems. The studied effects included the production of free radical intermediates during hemoglobin (Hb) oxidation by tert -butyl hydroperoxide, oxidative modification of Hb, and antioxidant properties of nitrosyl iron complexes. Measuring luminol chemiluminescence revealed that the antioxidant effect of TNICs was higher compared to DNIC-PO 4 - . DNIC-GS either did not exhibit antioxidant activity or exerted prooxidant effects at certain concentrations, which might have resulted from thiyl radical formation. TNICs and DNIC-PO 4 - efficiently protected the Hb heme group from decomposition by organic hydroperoxides. DNIC-GS did not exert any protective effects on the heme group; however, it abolished oxoferrylHb generation. TNICs inhibited the formation of Hb multimeric forms more efficiently than DNICs. Thus, TNICs had more pronounced antioxidant activity than DNICs in Hb-containing systems.

Thiosulfate (S 2 O 3 2- ) is an important ligand to complex metal cations, however, the reactivity of metal-thiosulfate complexes has barely been mentioned. In this study, the reactivity of the Cu(II)-S 2 O 3 2- system in the reduction of Cr(VI) was investigated. Kinetic results show that the reduction rates of Cr(VI) decrease with increasing pH values from 3.0 to 5.0, and 94.3% and 97.5% of 10 mg L -1 Cr(VI) was rapidly reduced within 1 min at pH 3.0 and within 30 min at pH 5.0, respectively at the molar ratio of Cu(II):S 2 O 3 2- of 0.05. We rule out the contributions of S species of tetrathionate (S 4 O 6 2- ) and sulfite (SO 3 2- ) to Cr(VI) reduction and point out that the produced Cu(I) in the Cu(II)-S 2 O 3 2- system is the key reductant that mediates the reduction of Cr(VI). We suggest that complexation between Cu(II) and S 2 O 3 2- with the formation of Cu II (S 2 O 3 ) 2 2- is the pre-requisite for the formation of Cu I (S 2 O 3 ) n 1-2n , which plays an important role in Cr(VI) reduction, accompanied by the re-oxidation of Cu(I) to Cu(II) by Cr(VI), achieving the rapid redox cycling of Cu(II)-Cu(I)-Cu(II). Such a redox cycle also mediates the denitrification process of NO 2 - to NH 3 /NH 4 + under weakly acidic conditions. This study enriches our understanding on the reducing reactivity of the Cu(II)-S 2 O 3 2- system and the importance of the Cu(II)-Cu(I)-Cu(II) redox cycle towards environmental oxidizing contaminants., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Surface-enhanced Raman spectroscopy (SERS), as a label-free, highly sensitive analytical method, has become an important tool for providing substance fingerprints. In this study, silver nanoparticles containing thiosulfate ions and calcium ions (Ag@SCNPs) have been used as an enhanced substrate to eliminate the interference of impurities on DNA signals. Intrinsic structural information on single-strand DNA (ssDNA) was directly obtained through SERS. The improved enhancement system was used to explore the base-stacking rules of ssDNA in a solution environment. For the first time, single-base insertion mutations and deletion mutations, as well as their exact mutation sites, were identified, and Raman spectra with high stability, repeatability, and high signal-to-noise ratio were obtained. The method is simple, fast, and accurate, and the detection process is nondestructive. It has potential to be applied in the fields of medical diagnosis and genetics research., (© 2021. Springer-Verlag GmbH Germany, part of Springer Nature.)

Iodine is an essential component for fetal neurodevelopment and maternal thyroid function. Urine iodine is the most widely used indicator of iodine status. In this study, a novel validated ion-pair HPLC-UV method was developed to measure iodine concentration in clinical samples. A sodium thiosulfate solution was added to the urine sample to convert the total free iodine to iodide. Chromatographic separation was achieved in a Pursuit XRs C8 column. The mobile phase consisted of acetonitrile and a water phase containing 18-crown-6-ether, octylamine and sodium dihydrogen phosphate. Validation parameters, such as accuracy, precision, limits of detection and quantification, linearity and stability, were determined. Urinary samples from pregnant women were used to complete the validation and confirm the method's applicability. In the studied population of 93 pregnant women, the median UIC was lower in the group without iodine supplementation (117 µg/L, confidence interval (%CI): 95; 138) than in the supplement group (133 µg/L, %CI: 109; 157). In conclusion, the newly established ion-pair HPLC-UV method was adequately precise, accurate and fulfilled validation the criteria for analyzing compounds in biological fluids. The method is less complicated and expensive than other frequently used assays and permits the identification of the iodine-deficient subjects.

The present study identified the active radical species in acidic sodium chlorite and investigated the feasibility of quantifying these species with the diethylphenylenediamine (DPD) method. Electron spin resonance (ESR) spectroscopy was used to identify the active species generated in solutions containing sodium chlorite (NaClO2). The ESR signal was directly observed in an acidified sodium chlorite (ASC) aqueous solution at room temperature. This ESR signal was very long-lived, indicating that the radical was thermodynamically stable. The ESR parameters of this signal did not coincide with previously reported values of the chlorine radical (Cl●) or chlorine dioxide radical (O = Cl●-O and O = Cl-O●). We refer to this signal as being from the chloroperoxyl radical (Cl-O-O●). Quantum chemical calculations revealed that the optimal structure of the chloroperoxyl radical is much more thermodynamically stable than that of the chlorine dioxide radical. The UV-visible spectrum of the chloroperoxyl radical showed maximum absorbance at 354 nm. This absorbance had a linear relationship with the chloroperoxyl radical ESR signal intensity. Quantifying the free chlorine concentration by the DPD method also revealed a linear relationship with the maximum absorbance at 354 nm, which in turn showed a linear relationship with the chloroperoxyl radical ESR signal intensity. These linear relationships suggest that the DPD method can quantify chloroperoxyl radicals, which this study considers to be the active species in ASC aqueous solution., Competing Interests: The authors have read the journal’s policy and have the following competing interests: HK, KN, IH, and HG are employees of Sankei Co. Ltd. This does not alter our adherence to PLOS ONE policies on sharing data and materials. There are no patents, products in development or marketed products associated with this research to declare.

Peroxydisulfate-based advanced oxidation process has drawn increasing interest recently. Quenching the residual peroxydisulfate is essential for the accurate measurement of the concentration of target pollutants. However, it was rarely discussed which reductant is best for peroxydisulfate quenching. In this study, how the quenching of peroxydisulfate by four commonly used quenchers (methanol, ascorbic acid, sodium thiosulfate and sodium sulfite) affected the concentration of carbamazepine was investigated. Sodium sulfite reacted with carbamazepine directly, with the highest removal rate up to 39%. Higher carbamazepine removal rate was achieved by peroxydisulfate/sodium sulfite than by sodium sulfite alone. SO 3 •- and SO 5 •- rather than SO 4 •- played the major role in carbamazepine removal by sodium sulfite or peroxydisulfate/sodium sulfite. Methanol was found unable to reduce peroxydisulfate. Ascorbic acid, when used with a concentration more than three times higher than that of peroxydisulfate, was the best quencher with the lowest carbamazepine removal rate observed at a pH range of 3.5-10.0. Sodium thiosulfate was unfit for peroxydisulfate quenching at pH 3.5 as it was decomposed and formed bisulfite under strong acidic condition. The results of this study provided valuable guidance to the selection of proper quenchers for peroxydisulfate-related advanced oxidation processes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Shewanella oneidensis MR-1 is a dissimilatory metal-reducing bacterium capable of reducing various metal and sulfur compounds and precipitating them in nanoparticulate form. Here, we report the synthesis of molybdenum disulfide nanomaterials at the site of S. oneidensis biofilms grown in the presence of molybdenum trioxide and sodium thiosulfate. Samples from the growth medium were imaged using scanning electron microscopy and characterized using transmission electron microscopy, energy-dispersive x-ray spectroscopy, absorbance spectroscopy, and x-ray diffraction. These methods revealed the presence of molybdenum disulfide nanoparticle aggregates 50-300 nm in diameter with both hexagonal and rhombohedral polytypes. As a biosynthesis method for molybdenum sulfide, the use of S. oneidensis offers the advantage of significantly reduced heat and chemical solvent input compared to conventional methods of synthesizing molybdenum disulfide nanoparticles.

Thiosulfate leaching combined with ion-exchange resins is an innovative alternative for gold recovery. According to the properties of activated carbon, it could replace resins in the gold recovery process, improve efficiency, and reduce operating cost. In this research, the adsorption process of gold thiosulfate complex on thiol-modified activated carbon was studied. Thioglycolic acid (ATG) was impregnated in activated carbon, and its adsorption ability was tested with synthetic solutions of gold and sodium thiosulfate (Au 10 mg·L -1 , Na 2 S 2 O 3 0.1 mol·L -1 , pH = 10.0). Carbon was characterized by infrared spectroscopy, SEM-EDS, PZC titration, hardness number measures, and proximal analysis. Synthetic solutions were also characterized by UV-vis spectroscopy and cyclic voltammetry. The percentage of volatile material increased from 10.0 to 13.9% due to the impregnation process of ATG. Infrared spectra show characteristic bands of C-H, S-H, and C-S bonds. In the adsorption tests, the ATG-impregnated carbon achieved 91% of gold recovery, while the same amount of ATG in the liquid phase stirred with unmodified activated carbon reached 90% of gold recovery. The 44.9% of gold recovered with activated carbon impregnated with ATG was eluted with sodium cyanide ([NaCN] = 0.2 mol·L -1 ; [NaOH] = 0.25 mol·L -1 ; [CH 3 CH 2 OH] = 30% V / V ; pH = 12.0; t = 24 h). These results suggest the gold transferred from the thiosulfate complex to a new gold thiolate complex.

Sulfane sulfur is a divalent sulfur atom bonded to another sulfur which is very reactive and labile. Compounds containing this reactive sulfur include persulfides, polysulfides, thiosulfate, thiosulfinates, polythionates, and elemental sulfur. Sulfane sulfur appears in a number of biologically important compounds, including thiocysteine, thiocystine and thiotaurine, products of the cysteine metabolism, as well as glutathione persulfide. Sulfane sulfur compounds can modify cysteine residues in proteins via an S-sulfhydration reaction to produce protein persulfides. It has been also postulated that cysteine persulfides can be incorporated into proteins during translation. Recently, the sulfane sulfur compounds, especially the persulfides and polysulfides, have attracted increasing interest due to their regulatory and antioxidant properties. Compounds containing sulfane sulfur are also regarded as a form of H2S storage, which can easily release this gasotransmitter in response to biological signals. Both reactive sulfur species (H2S and sulfane sulfur) always coexist in biological systems. This review is focused on new findings in the field of sulfane sulfur's biological role, and disruption of its level in some patho/physiological conditions. A few sulfane sulfur donors with potential applications are presented. In recent years, in parallel to increasing interest in biological importance of sulfane sulfur, new analytical methods have been developed for sensitive and reliable determination of its level in the cells and tissues.

Microbially influenced corrosion (MIC) results in significant damage to metallic materials in many industries. Anaerobic sulfate-reducing bacteria (SRB) have been well studied for their involvement in these processes. Highly corrosive environments are also found in pulp and paper processing, where chloride and thiosulfate lead to the corrosion of stainless steels. Acidithiobacillus ferrooxidans is a critically important chemolithotrophic acidophile exploited in metal biomining operations, and there is interest in using A. ferrooxidans cells for emerging processes such as electronic waste recycling. We explored conditions under which A. ferrooxidans could enable the corrosion of stainless steel. Acidic medium with iron, chloride, low sulfate, and pyrite supplementation created an environment where unstable thiosulfate was continuously generated. When combined with the chloride, acid, and iron, the thiosulfate enabled substantial corrosion of stainless steel (SS304) coupons (mass loss, 5.4 ± 1.1 mg/cm 2 over 13 days), which is an order of magnitude higher than what has been reported for SRB. There results were verified in an abiotic flow reactor, and the importance of mixing was also demonstrated. Overall, these results indicate that A. ferrooxidans and related pyrite-oxidizing bacteria could produce aggressive MIC conditions in certain environmental milieus. IMPORTANCE MIC of industrial equipment, gas pipelines, and military material leads to billions of dollars in damage annually. Thus, there is a clear need to better understand MIC processes and chemistries as efforts are made to ameliorate these effects. Additionally, A. ferrooxidans is a valuable acidophile with high metal tolerance which can continuously generate ferric iron, making it critical to copper and other biomining operations as well as a potential biocatalyst for electronic waste recycling. New MIC mechanisms may expand the utility of these cells in future metal resource recovery operations., (Copyright © 2019 American Society for Microbiology.)

Although 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane (DDT) was banned in the United States in 1972, it is still often detected in sediments where pyrogenic carbonaceous matter (PCM) and sulfate-reducing bacteria (SRB) co-exist. In this study, we found that 70.2 ± 0.2% of DDT disappeared in the presence of SRB and graphite powder, a model PCM, after 21 days at pH 7. Our results suggest that the observed DDT decay was due to the reaction between graphite powder and the reduced sulfur species that were produced by SRB. No biofilm formation was observed on the surface of graphite powder. Rather, the activity of SRB was inhibited by the presence of graphite powder. To understand the involvement of PCM in DDT decay, electrochemical cells and batch reactor experiments with sulfur-pretreated PCM as well as direct electrochemical reduction by a potentiostat were employed. Our results suggest that polysulfide, sulfide, sulfite, and thiosulfate could all react with PCM, forming surface-bound intermediates that subsequently led to DDT decay. The reactivity of reduced sulfur species was the highest for polysulfide, followed by sulfide, sulfite, and thiosulfate., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The bioprocessing of amino acids to branched-chain fatty acids and alcohols is described using Thermoanaerobacter strain AK85. The amino acid utilization profile was evaluated without an electron scavenger, with thiosulfate, and in a co-culture with a methanogen. There was an emphasis on the production of branched-chain alcohols and fatty acids from the branched-chain amino acids, particularly the influence of culture conditions which was investigated using isoleucine, which revealed that the concentration of thiosulfate was of great importance for the branched-chain alcohols/fatty acid ratio produced. Kinetic studies show that branched-chain amino acid fermentation is relatively slow as compared to glucose metabolism with the concentrations of the branched-chain alcohol increasing over time. To understand the flow of electrons and to investigate if the branched-chain fatty acid was being converted to branched-chain alcohol, enzyme assays and fermentation studies using 13 C-labeled leucine and 3-methyl-1-butyrate were performed which indeed suggest that carboxylic acid reduction is a source of branched-chain alcohols when Thermoanaerobacter strain AK85 was cultivated with thiosulfate as an electron scavenger.

A quenching agent is commonly added to chlorinated, reclaimed water during sample collection to prevent chlorine-mediated die-off of viable microbiota. However, the effect of quenching on downstream 16S rRNA-based bacterial community analyses is unclear. We conducted a side-by-side comparison of 16S rRNA sequencing data from reclaimed water samples quenched with sodium thiosulfate and non-quenched samples. Our data showed that 16 S rRNA processing and sequencing methods, and resulting bacterial profiles, were not negatively impacted by quenching., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The inhibitory effect of thiourea (TUA), ammonium thiosulfate (TSA) and amidosulfonic acid (ASA) on the reactivity of fly ash air was investigated using a thermobalance at different heating rates (5, 10 and 20 K min -1 ). A model fly ash (activated carbon + 50 wt% CuCl 2 ·2H 2 O, pyrolyzed at 700 °C and washed) was used as carbonaceous material. Adding CuCl 2 ·2H 2 O to the activated carbon led to an increased rate of decomposition with the air's oxygen. TUA and TSA behaved in a similar way, accelerating the decomposition of the model fly ash. ASA also accelerated the decomposition but to a lower extent. We postulate that the increase in decomposition rate is caused by a reaction between carbonaceous material and N and S-containing compounds. The formation of nitrogenated and sulphured compounds was confirmed by TG-MS. A kinetic model based on a single reaction of order 0.6 showed very good correlations with all the heating rates tested in oxidant atmosphere., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

To exploit the advantages of less electron donor consumptions in partial-denitrification (denitratation, NO 3 - → NO 2 - ) as well as less sludge production in autotrophic denitrification (AD) and anammox, a novel biological nitrogen removal (BNR) process through combined anammox and thiosulfate-driven denitratation was proposed here. In this study, the ratio of S 2 O 3 2- -S/NO 3 - -N and pH are confirmed to be two key factors affecting the thiosulfate-driven denitratation activity and nitrite accumulation. Simultaneous high denitratation activity and substantial nitrite accumulation were observed at initial S 2 O 3 2- -S/NO 3 - -N ratio of 1.5:1 and pH of 8.0. The optimal pH for the anammox reaction is determined to be 8.0. A sequential batch reactor (SBR) and an up-flow anaerobic sludge blanket (UASB) reactor were established to proceed the anammox and the high-rate thiosulfate-driven denitratation, respectively. Under the ambient temperature of 35 °C, the total nitrogen removal efficiency and capacity are 73% and 0.35 kg N/day/m 3 in the anammox-SBR. At HRT of 30 min, the NO 3 - removal efficiency could achieve above 90% with the nitrate-to-nitrite transformation ratio of 0.8, implying the great potential to apply the thiosulfate-driven denitratation & anammox system for BNR with minimal sludge production. Without the occurrence of denitritation (NO 2 - → N 2 O → N 2 ), theoretically no N 2 O could be emitted from this BNR system. This study could shed light on how to operate a high rate BNR system targeting to electron donor and energy savings as well as biowastes minimization and greenhouse gas reductions., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Despite its potentially high relevance for nitrate removal in freshwater environments limited in organic carbon, chemolithoautotrophic denitrification has rarely been studied in oligotrophic groundwater. Using thiosulfate and H2 as electron donors, we established a chemolithoautotrophic enrichment culture from groundwater of a carbonate-rock aquifer to get more insight into the metabolic repertoire, substrate turnover, and transcriptional activity of subsurface denitrifying consortia. The enriched consortium was dominated by representatives of the genus Thiobacillus along with denitrifiers related to Sulfuritalea hydrogenivorans, Sulfuricella denitrificans, Dechloromonas sp. and Hydrogenophaga sp., representing the consortium's capacity to use multiple inorganic electron donors. Microcosm experiments coupled with Raman gas spectroscopy demonstrated complete denitrification driven by reduced sulfur compounds and hydrogen without formation of N2O. The initial nitrate/thiosulfate ratio had a strong effect on nosZ transcriptional activity and on N2 formation, suggesting similar patterns of the regulation of gene expression as in heterotrophic denitrifiers. Sequence analysis targeting nirS and nosZ transcripts identified Thiobacillus denitrificans-related organisms as the dominant active nirS-type denitrifiers in the consortium. An additional assessment of the nirS-type denitrifier community in the groundwaterclearly confirmed the potential for sulfur- and hydrogen-dependent chemolithoautotrophic denitrification as important metabolic feature widely spread among subsurface denitrifiers at the Hainich Critical Zone Exploratory.

The neuropeptide substance P (SP) is known to stimulate wound healing by regulating the production of relevant cytokines as well as cell proliferation and migration. However, the therapeutic application of SP is limited by its low stability under biological conditions and oxidation during purification, formulation, and storage. To address this problem, we developed a novel formulation of SP as an SP gel, and investigated its wound healing activity both in vitro and in vivo. SP in SP gel was stable at various temperatures for up to 4 weeks. In vitro, SP gel exhibited more potential as a candidate wound-healing agent than SP alone, as evidenced by the observed increases in the proliferation and migration of human epidermal keratinocytes and human dermal fibroblasts. In vivo experiments showed that SP gel treatment enhanced the healing of full-thickness wounds in mice as compared to SP alone. These results demonstrate the benefits of SP gel as a promising topical agent for wound treatment.

Drywall manufactured in China released foul odors attributed to volatile sulfur compounds. These included hydrogen sulfide, methyl mercaptan, and sulfur dioxide. Given that calcium sulfate is the main component of drywall, one would suspect bacterial reduction of sulfate to sulfide as the primary culprit. However, when the forensics, i.e., the microbial and chemical signatures left in the drywall, are studied, the evidence suggests that, rather than dissimilatory sulfate reduction, disproportionation of elemental sulfur to hydrogen sulfide and sulfate was actually the primary cause of the malodors. Forensic evidence suggests that the transformation of elemental sulfur went through several abiological and microbial stages: (1) partial volatilization of elemental sulfur during the manufacture of plaster of Paris, (2) partial abiotic disproportionation of elemental sulfur to sulfide and thiosulfate during the manufacture of drywall, (3) microbial disproportionation of elemental sulfur to sulfide and sulfate resulting in neutralization of all alkalinity, and acidification below pH 4, (4) acidophilic microbial disproportionation of elemental sulfur to sulfide and sulfuric acid, and (5) hydrogen sulfide volatilization, coating of copper fixtures resulting in corrosion, and oxidation to sulfur dioxide.

Utilization of bacterial volatilization can be problematic to remediate mercury (Hg)-contaminated soils because most of the Hg in soils is bound to soil particles. The objective of this study was to develop a two-stage system (chemical extraction followed by microbial reduction) for Hg-contaminated soil remediation. The tasks were to (1) select the extraction reagents for Hg extraction, (2) assess the effects of extraction reagents on the growth of Hg-reducing bacterial strains, and (3) evaluate the effectiveness of Ca 2+ and Mg 2+ addition on merA gene (Hg reductase) induction. Bacterial inhibition was observed with the addition of 0.1 M ethylenediaminetetraacetic acid or citric acid. Up to 65% of Hg was biotransformed (Hg concentration = 69 mg/kg) from the soils after a 24 h extraction using 0.5 M ammonium thiosulfate. Ca 2+ and Mg 2+ were selected because they have the same electric charge as Hg and the studied groundwater contained high concentrations of Ca 2+ and Mg 2+ . Results showed that the addition of 200 mg/L Ca 2+ or 650 mg/L Mg 2+ could reach effective merA induction. In the two-stage experiment, 120 mg/kg Hg-contaminated soils were extracted with 2 rounds of extraction processes for 10 h using 0.5 M ammonium thiosulfate. Approximately 77% of Hg was extracted from the soils after the first-step extraction process. Up to 81% of Hg 2+ was transformed from the washing solution via the biotransformation processes with Enterobacter cloacae addition and Ca 2+ and Mg 2+ supplementation. The two-stage remedial system has the potential to be developed into a practical technology to remediate Hg-contaminated sites., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Antifouling paint particles (APPs) are residues generated during maintenance of vessels. In boat maintenance areas of South America, waste generation and disposal are not completely regulated. Therefore, APPs can enter into the aquatic environment and act as a source of contamination by metals and other biocides. Thus, the aim of the present study was to evaluate the potential ecotoxicity of the metal mixture present in APPs leached under different salinities. Therefore, the copepod Acartia tonsa was exposed to different concentrations of a leachate solution prepared by the addition of APPs (1.25g/L) in artificial saline water (salinities 5, 15 and 30). Thereafter, complexing agents (EDTA and sodium thiosulfate) were added to the experimental media in order to evaluate metal influence in APPs toxicity. APPs leachate solutions were very toxic to A. tonsa, reaching an estimated LC 50 of 1% at salinities 5% and 15%, and 2% at salinity 30. The addition of the chelators in leachate solutions showed that metals are the major responsible compounds for the observed toxicity. Moreover, results from the calculated toxic units suggested a slightly synergic effect between Cu and Zn in the paint formulation. A metal speciation modelling showed that Zn was predominant as a free ion at all salinities, therefore, explaining the high leachate toxicity. Furthermore, the release of Zn was observed more at lower salinities, whereas Cu was observed at higher salinities. APPs are frequently released in estuarine systems, under conditions of salinity gradients. Therefore, navigated estuaries might be under the threat of this neglected residue., (Copyright © 2017 Elsevier Inc. All rights reserved.)

A comparative study on denitrifying sludge granulation with different electron donors (sulfide, thiosulfate and organics) was carried out. Longer time was spent on sulfide-denitrifying granular sludge (DGS) cultivation (88 days) than thiosulfate- and organics-DGS cultivations (57 days). All the three DGS were characterized in terms of particle size distribution, sludge settling ability (indicated by sludge volume index and settling velocity), permeability (indicated by fractal dimension) and extracellular polymeric substances (EPS, including polysaccharide and protein) secretion. Sludge productions in the three DGS-reactors were also monitored. The key functional microorganisms in three granular reactors were revealed via high through-put pyrosequencing analysis. Batch tests were performed to measure the denitrification activities of each DGS, including both denitratation (NO 3 -  → NO 2 - ) and denitritation (NO 2 -  → N 2 ). We found that thiosulfate-driven denitrifying sludge granulation (TDDSG) should be the most efficient and compact technology for effective BNR in municipal wastewater treatment. The findings of this study suggests the TDDSG could further increase the nitrogen removal potential in an enhanced sulfur cycle-driven bioprocess for co-treatment of wet flue gas desulfurization wastes with fresh sewage depending on three short-cut biological reactions, including: 1) short-cut biological sulfur reduction (SO 4 2- /SO 3 2-  → S 2 O 3 2- ); 2) thiosulfate-driven denitritation (S 2 O 3 2-  + NO 2 -  → SO 4 2-  + N 2 ↑); and 3) nitritation (NH 4 +  + O 2  → NO 2 - )., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Although the kinetics and transformation of methyl parathion have been investigated extensively, its abiotic degradation mechanism in anoxic sulfur-containing groundwater system is still not clear. In this work, the abiotic degradation of methyl parathion in anoxic sulfur-containing system mediated by natural organic matter (NOM) was investigated in batch experiments. It was found that the removal of methyl parathion (up to 80.7%) was greatly improved in sulfide containing NOM compared to those in sulfide alone (with 15.5%) and in NOM alone (almost negligible). Various sulfur species presented significant differences in behaviors methyl parathion degradation, but followed by the pseudo-first-order model well. No facilitated degradation of methyl parathion was observed in sulfite (SO 3 2- ) or thiosulfate (S 2 O 3 2- ) containing NOM such as anthraquinone. Although elemental sulfur (S 0 ) and cysteine could further improve the degradation rate of methyl parahtion, their impacts was very limited. The removal efficiency of methyl parathion in anoxic sulfur-containing system were related remarkably with NOM concentration and solution pH. Based on the transformation products identified by gas chromatography-mass spectrometer (GC/MS) and liquid chromatography high resolution mass spectrometer (LC/HRMS), both the nitro group reduction and hydrolysis (S N @C) processes by sulfide (HS - ) were further proved to be two predominant reaction mechanisms for the abiotic degradation of methyl parathion in anoxic sulfur-containing system. The results of this study help to understand the natural attenuation of methyl parathion under anoxic sulfide-containing groundwater system mediated by NOM., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Purpose: The present study examined the factors affecting the content of impurities of nimodipine (NMP) emulsion and the associated methods of compound protection., Methods: Destructive testing of NMP emulsion and its active pharmaceutical ingredient (API) were conducted, and ultracentrifugation was used to study the content of impurities in two phases. The impurity of NMP was measured under different potential of hydrogen (pH) conditions, antioxidants and pH-adjusting agents., Results: Following destruction, the degradation of NMP notably occurred in the basic environment. The consumption of the pH-adjusting agent NaOH was proportional to the production of impurities since the inorganic base and/or acid promoted the degradation of NMP. The organic antioxidants, notably amino acids with an appropriate length of intermediate chain and electron-donating side group, exhibited improved antioxidant effects compared with inorganic antioxidants. The minimal amount of impurities was produced following addition of 0.04% lysine and 0.06% leucine in the aqueous phase and adjustment of the pH to a range of 7.5-8.0 in the presence of acetic acid solution., Conclusion: NMP was more prone to degradation in an oxidative environment, in an aqueous phase and/or in the presence of inorganic pH-adjusting agents and antioxidants. The appropriate antioxidant and pH-adjusting agent should be selected according to the chemical structure, while destructive testing of the drug is considered to play the optimal protective effect., Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Hydrogen sulfide is a critical signaling molecule, but high concentrations cause cellular toxicity. A four-enzyme pathway in the mitochondrion detoxifies H 2 S by converting it to thiosulfate and sulfate. Recent studies have shown that globins like hemoglobin and myoglobin can also oxidize H 2 S to thiosulfate and hydropolysulfides. Neuroglobin, a globin enriched in the brain, was reported to bind H 2 S tightly and was postulated to play a role in modulating neuronal sensitivity to H 2 S in conditions such as stroke. However, the H 2 S reactivity of the coordinately saturated heme in neuroglobin is expected a priori to be substantially lower than that of the 5-coordinate hemes present in myoglobin and hemoglobin. To resolve this discrepancy, we explored the role of the distal histidine residue in muting the reactivity of human neuroglobin toward H 2 S. Ferric neuroglobin is slowly reduced by H 2 S and catalyzes its inefficient oxidative conversion to thiosulfate. Mutation of the distal His 64 residue to alanine promotes rapid binding of H 2 S and its efficient conversion to oxidized products. X-ray absorption, EPR, and resonance Raman spectroscopy highlight the chemically different reaction options influenced by the distal histidine ligand. This study provides mechanistic insights into how the distal heme ligand in neuroglobin caps its reactivity toward H 2 S and identifies by cryo-mass spectrometry a range of sulfide oxidation products with 2-6 catenated sulfur atoms with or without oxygen insertion, which accumulate in the absence of the His 64 ligand., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)

The Sox pathway found in many sulfur bacteria oxidizes thiosulfate to sulfate. Pathway intermediates are covalently bound to a cysteine residue in the carrier protein SoxYZ. We have used biochemical complementation by SoxYZ-conjugates to probe the identity of the intermediates in the Sox pathway. We find that unconjugated SoxYZ and SoxYZ-S-sulfonate are unlikely to be intermediates during normal turnover in disagreement with current models. By contrast, conjugates with multiple sulfane atoms are readily metabolised by the Sox pathway. The most parsimonious interpretation of these data is that the true carrier species in the Sox pathway is a SoxYZ-S-sulfane adduct.

Screening of optimal chelating ligands which not only have high capacities to enhance plant uptake of mercury (Hg) from soil but also can decrease bioavailable Hg concentration in soil is necessary to establish a viable chemically-assisted phytoextraction. Therefore, Brassica juncea was exposed to historically Hg-contaminated soil (total Hg, 90 mg kg -1 ) to investigate the efficiency of seven chelating agents [ammonium thiosulphate, sodium thiosulphate, ammonium sulfate, ammonium chloride, sodium nitrate, ethylenediaminetetraacetic acid (EDTA), and sodium sulfite] at enhancing Hg phytoextraction; the leaching of bioavailable Hg caused by these chelating agents was also investigated. The Hg concentration in control (treated with double-distilled water) plant tissues was below 1 mg kg -1 . The remarkably higher Hg concentration was found in plants receiving ammonium thiosulphate and sodium sulfite treatments. The bioaccumulation factors and translocation factors of ammonium thiosulphate and sodium sulfite treatments were significantly higher than those of the other treatments. The more efficient uptake of Hg by plants upon treatment with ammonium thiosulphate and sodium sulfite compared to the other treatments might be explained by the formation of special Hg-thiosulphate complexes that could be preferentially taken up by the roots and transported in plant tissues. The application of sulfite significantly increased bioavailable Hg concentration in soil compared with that in initial soil and control soil, whereas ammonium thiosulphate significantly decreased bioavailable Hg concentration. The apparent decrease of bioavailable Hg in ammonium thiosulphate-treated soil compared with that in sodium sulfite-treated soil might be attributable to the unstable Hg-thiosulphate complexes formed between thiosulphate and Hg; they could react to produce less bioavailable Hg in the soil. The results of this study indicate that ammonium thiosulphate may be an optimal chelating ligand for phytoextraction due to its great potential to enhance Hg accumulation in plants while decreasing bioavailable Hg concentration in the soil., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A novel biological nitrogen removal system based on nitritation coupled with thiosulfate-driven denitritation (Nitritation-TDD) was developed to achieve a high nitrogen removal rate and low sludge production. A nitritation sequential batch reactor (nitritation SBR) and an anoxic up-flow sludge bed (AnUSB) reactor were applied for effective nitritation and denitritation, respectively. Above 75% nitrite was accumulated in the nitritation SBR with an influent ammonia loading rate of 0.43 kg N/d/m(3). During Nitritation-TDD operation, particle sizes (d50) of the sludge decreased from 406 to 225 um in nitritation SBR and from 327-183 um in AnUSB reactor. Pyrosequencing tests revealed that ammonium-oxidizing bacteria (AOB) population was stabilized at approximately 7.0% (calculated as population of AOB-related genus divided by the total microbial population) in the nitritation SBR. In contrast, nitrite-oxidizing bacteria (NOB) population decreased from 6.5-0.6% over the same time, indicating the effective nitrite accumulation in the nitritation SBR. Thiobacillus, accounting for 34.2% in the AnUSB reactor, was mainly responsible for nitrogen removal via autotrophic denitritation, using an external source of thiosulfate as electron donor. Also, it was found that free nitrous acid could directly affect the denitritation activity.

Organic Carbon added to low ratio of carbon to nitrogen (C/N ratio) wastewater to enhance heterotrophic denitrification performance might lead to higher operating costs and secondary pollution. In this study, sodium thiosulfate (Na2S2O3) was applied as an electron donor for a gravel filter (one kind of constructed wetland) to investigate effects of hydraulic retention time (HRT) and water temperature on the nitrate removal efficiency. The results show that with an HRT of 12 h, the average total nitrogen (TN) removal efficiencies were 91% at 15-20 °C and 18% at 3-6 °C, respectively. When HRT increased to 24 h, the average TN removal increased accordingly to 41% at 3-6 °C, suggesting denitrification performance was improved by extended HRT at low water temperatures. Due to denitrification, 96% of added nitrate nitrogen (NO3(-)-N) was converted to nitrogen gas, with a mean flux of nitrous oxide (N2O) was 0.0268-0.1500 ug m(-2) h(-1), while 98.86% of thiosulfate was gradually converted to sulfate throughout the system. Thus, our results show that the sulfur driven autotrophic denitrification constructed wetland demonstrated an excellent removal efficiency of nitrate for wastewater treatment. The HRT and water temperature proved to be two influencing factors in this constructed wetland treatment system., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Cyanobacterial harmful algal blooms occur in freshwater lakes, ponds, rivers, and reservoirs, and in brackish waters throughout the world. The wide variety of cyanotoxins and their congeners can lead to frequent exposure of humans through consumption of meat, fish, seafood, blue-green algal products and water, accidental ingestion of contaminated water and cyanobacterial scum during recreational activities, and inhalation of cyanobacterial aerosols. Cyanotoxins can also occur in the drinking water supply. In order to monitor human exposure, sensitive analytical methods such as enzyme linked immunosorbent assay and liquid chromatography-mass spectrometry are often used. Regardless of the analytical method of choice, some problems regularly occur during sample collection, treatment, storage, and preparation which cause toxin loss and therefore underestimation of the true concentration. To evaluate the potential influence of sample treatment, storage and preparation materials on surface and drinking water samples, the effects of different types of materials on toxin recovery were compared. Collection and storage materials included glass and various types of plastics. It was found that microcystin congeners LA and LF adsorbed to polystyrene, polypropylene, high density polyethylene and polycarbonate storage containers, leading to low recoveries (<70%), cylindrospermopsin and saxitoxin did not adsorb to the containers tested. Therefore, this study shows that glass or polyethylene terephthalate glycol containers are the materials of choice for collection and storage of samples containing the cyanotoxins cylindrospermopsin, microcystins, and saxitoxin. This study also demonstrated that after 15 min chlorine decreased the concentration of microcystin LR to <40%, microcystin LA and saxitoxin to <15%, therefore quenching of drinking water samples immediately upon sample collection is critical for accurate analysis. In addition, the effect of various drinking water treatment chemicals on toxin recovery and the behavior of those chemicals in the enzyme linked immunosorbent assays were also studied and are summarized., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Sulfide biooxidation by the novel sulfide-oxidizing bacteria Pseudomonas sp. C27, which could perform autotrophic and heterotrophic denitrification in mixotrophic medium, was studied in batch and continuous systems. Pseudomonas sp. C27 was able to oxidize sulfide at concentrations as high as 17.66 mM. Sulfide biooxidation occurred in two distinct stages, one resulting in the formation of sulfur with nitrate reduction to nitrite, followed by thiosulfate formation with nitrite reduction to N2. The composition of end-products was greatly impacted by the ratio of sulfide to nitrate initial concentrations. At a ratio of 0.23, thiosulfate represented 100% of the reaction products, while only 30% with a ratio of 1.17. In the continuous bioreactor, complete removal of sulfide was observed at sulfide concentration as high as 9.38 mM. Overall sulfide removal efficiency decreased continuously upon further increases in influent sulfide concentrations. Based on the experimental data kinetic parameter values were determined. The value of maximum specific growth rate, half saturation constant, decay coefficient, maintenance coefficient and yield were to be 0.11 h(-1), 0.68 mM sulfide, 0.11 h(-1), 0.21 mg sulfide/mg biomass h and 0.43 mg biomass/mg sulfide, respectively, which were close to or comparable with those reported in literature by other researches.

Differently-treated crops straw is being widely used to fertilize soil, while the potential impacts of straw amendment on the biogeochemistry and phytoavailability of mercury in contaminated soils are largely unknown. In the present study, differently-treated rice straw (dry straw, composted straw, straw biochar, and straw ash) was incorporated into mercury-contaminated soil at an environment relevant level (1/100, w/w), and mercury speciation, methylmercury (MeHg) phytoavailability (using ammonium thiosulfate extraction method, validated elsewhere) and bioaccumulation (in Indian mustard Brassica junceas) were quantified. Our results indicated that incorporating straw biochar or composted straw into soil would decrease phytoavailable MeHg levels, possibly due to the strong binding of MeHg with particulate organic matter in amended straw ('MeHg immobilization effect'). Consequently, MeHg accumulation in aboveground tissue of Indian mustard harvested from straw biochar-amended soil decreased by 20% compared to the control. Differently, incorporation of dry straw resulted in elevated MeHg levels in soil ('Mercury methylation effect'). Decomposition of amended dry straw in soil would evidently increase DOC levels (averagely 40%-195% higher than the control), which may subsequently mobilize MeHg in the soil ('MeHg mobilization effect'). Accordingly, incorporation of dry straw led to increased phytoavailable MeHg levels in the soil and doubled MeHg accumulation in Indian mustard. Our results provided the first evidence that incorporating differently-treated rice straw into soil could have diverse effects on mercury biogeochemistry and phytoavailability, which should be taken into account in risk assessment or soil remediation., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The bacterial Sox (sulfur oxidation) pathway is an important route for the oxidation of inorganic sulfur compounds. Intermediates in the Sox pathway are covalently attached to the heterodimeric carrier protein SoxYZ through conjugation to a cysteine on a protein swinging arm. We have investigated how the carrier protein shuttles intermediates between the enzymes of the Sox pathway using the interaction between SoxYZ and the enzyme SoxB as our model. The carrier protein and enzyme interact only weakly, but we have trapped their complex by using a "suicide enzyme" strategy in which an engineered cysteine in the SoxB active site forms a disulfide bond with the incoming carrier arm cysteine. The structure of this trapped complex, together with calorimetric data, identifies sites of protein-protein interaction both at the entrance to the enzyme active site tunnel and at a second, distal, site. We find that the enzyme distinguishes between the substrate and product forms of the carrier protein through differences in their interaction kinetics and deduce that this behavior arises from substrate-specific stabilization of a conformational change in the enzyme active site. Our analysis also suggests how the carrier arm-bound substrate group is able to outcompete the adjacent C-terminal carboxylate of the carrier arm for binding to the active site metal ions. We infer that similar principles underlie carrier protein interactions with other enzymes of the Sox pathway.

It is now accepted that primordial non-cellular RNA communities must have been subject to a periodic drive in order to replicate and prosper. We have proposed the oxidation of thiosulfate by hydrogen peroxide as this drive. This reaction system behaves as (i) a thermochemical and (ii) a pH oscillator, and in this work, we unify (i) and (ii) for the first time. We report thermally self-consistent, dynamical simulations in which the system transitions smoothly from nearly isothermal pH to fully developed thermo-pH oscillatory regimes. We use this oscillator to drive simulated replication of a 39-bp RNA species. Production of replicated duplex under thermo-pH drive was significantly enhanced compared with that under purely thermochemical drive, effectively allowing longer strands to replicate. Longer strands are fitter, with more potential to evolve enzyme activity and resist degradation. We affirm that concern over the alleged toxicity of hydrogen peroxide to life is largely misplaced in the current context, we survey its occurrence in the solar system to motivate its inclusion as a biosignature in the search for life on other worlds and highlight that pH oscillations in a spatially extended, bounded system manifest as the fundamental driving force of life: a proton gradient., (© 2015 The Author(s).)

Hydrolysis of cellulose to glucose is the critical step for transferring the lignocellulose to the industrial chemicals. For improving the conversion rate of cellulose of corn stover to glucose, the cocktail of celllulase with other auxiliary enzymes and chemicals was studied in this work. Single factor tests and Response Surface Methodology (RSM) were applied to optimize the enzyme mixture, targeting maximum glucose release from corn stover. The increasing rate of glucan-to-glucose conversion got the higher levels while the cellulase was added 1.7μl tween-80/g cellulose, 300μg β-glucosidase/g cellulose, 400μg pectinase/g cellulose and 0.75mg/ml sodium thiosulphate separately in single factor tests. To improve the glucan conversion, the β-glucosidase, pectinase and sodium thiosulphate were selected for next step optimization with RSM. It is showed that the maximum increasing yield was 45.8% at 377μg/g cellulose Novozyme 188, 171μg/g cellulose pectinase and 1mg/ml sodium thiosulphate.

Three distinct -S and -NH2 or NH4(+) containing compounds, including ammonium thiosulfate, aminosulfonic acid and thiourea, were studied as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) inhibitors. All these three -S and -N containing compounds tested show strong suppression of PCDD/Fs formation, especially for thiourea which has not been studied before. With a (S+N)/Cl molar ratio of only 0.47, thiourea could inhibit 97.3% of PCDD/Fs and even 99.8% of I-TEQ. At an unusually high de novo test temperature (650 °C), the PCDD/Fs' formation was still very low but also the inhibition capacity of thiourea was weak, with an efficiency of 59% for PCDD/Fs when with a (S+N)/Cl molar ratio of 1.40. The results also revealed that the inhibition capability of the combined -S/-NH2 or -S/NH4(+) suppressant was strongly influenced by both the nature of the functional group of nitrogen and the value of the molar ratio (S+N)/Cl. The amine functional group -NH2 tends to be more efficient than ammonium NH4(+) and within a certain range a higher (S+N)/Cl value leads to a higher inhibition efficiency. Moreover, the emission of gases was continuously monitored: the Gasmet results revealed that SO2, HCN and NH3 were the most important decomposition products of thiourea. Thiourea is non-toxic, environment-friendly and can be sprayed into the post-combustion zone in form of powder or aqueous solution. The cost of thiourea at least can be partially compensated by its high inhibition efficiency. Therefore, the application of thiourea in a full-scale incinerator system is promising and encouraging., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The kinetics of the reactions of tetrathionate with S(IV) species and with thiosulfate in slightly acidic and neutral media were studied concurrently at 25.0 ± 0.1 °C by simultaneous high-performance liquid chromatography monitoring of the concentrations of polythionates (including trithionate, tetrathionate, and pentathionate), thiosulfate, and sulfite. The tetrathionate-sulfite and tetrathionate-thiosulfate reactions were found to be first-order with respect to both reactants. The tetrathionate-sulfite reaction was found to be pH-dependent under the conditions studied. In contrast, the tetrathionate-thiosulfate reaction was experimentally demonstrated to be pH-independent at neutral medium, where the pKa2 value of sulfurous acid plays a key role, whereas under slightly acidic conditions, between pH 4 and 5 the consumption of tetrathionate during the course of reaction was found to become pH-dependent. We show that the pH dependencies in both systems can be readily explained by the reactivity difference between sulfite and bisulfite toward the β-sulfur of the tetrathionate. A simple two-step kinetic model incorporating the protonation equilibrium of sulfite is proposed on the basis of the simultaneous evaluation of the kinetic curves of the two systems, which allowed us to determine reliable rate coefficients for both the forward and backward reactions. Furthermore, the powerful ability of simultaneously evaluating the two chemical systems to yield reliable rate coefficients of the kinetic model is demonstrated.

We present coupled sulfur and oxygen isotope data from sulfur nodules and surrounding gypsum, as well as iron and manganese concentration data, from the Lisan Formation near the Dead Sea (Israel). The sulfur isotope composition in the nodules ranges between -9 and -11‰, 27 to 29‰ lighter than the surrounding gypsum, while the oxygen isotope composition of the gypsum is constant around 24‰. The constant sulfur isotope composition of the nodule is consistent with formation in an 'open system'. Iron concentrations in the gypsum increase toward the nodule, while manganese concentrations decrease, suggesting a redox boundary at the nodule-gypsum interface during aqueous phase diagenesis. We propose that sulfur nodules in the Lisan Formation are generated through bacterial sulfate reduction, which terminates at elemental sulfur. We speculate that the sulfate-saturated pore fluids, coupled with the low availability of an electron donor, terminates the trithionate pathway before the final two-electron reduction, producing thionites, which then disproportionate to form abundant elemental sulfur.

H2S derived from organic thiol metabolism has been proposed serve as an oxygen sensor in a variety of systems because of its susceptibility to oxidation and its ability to mimic hypoxic responses in numerous oxygen-sensing tissues. Thiosulfate, an intermediate in oxidative H2S metabolism can alternatively be reduced and regenerate H2S. We propose that this contributes to the H2S-mediated oxygen-sensing mechanism. H2S formation from thiosulfate in buffers and in a variety of mammalian tissues and in lamprey dorsal aorta was examined in real time using a polarographic H2S sensor. Inferences of intracellular H2S production were made by examining hypoxic pulmonary vasoconstriction (HPV) in bovine pulmonary arteries under conditions in which increased H2S production would be expected and in mouse and rat aortas, where reducing conditions should mediate vasorelaxation. In Krebs-Henseleit (mammalian) and Cortland (lamprey) buffers, H2S was generated from thiosulfate in the presence of the exogenous reducing agent, DTT, or the endogenous reductant dihydrolipoic acid (DHLA). Both the magnitude and rate of H2S production were greatly increased by these reductants in the presence of tissue, with the most notable effects occurring in the liver. H2S production was only observed when tissues were hypoxic; exposure to room air, or injecting oxygen inhibited H2S production and resulted in net H2S consumption. Both DTT and DHLA augmented HPV, and DHLA dose-dependently relaxed precontracted mouse and rat aortas. These results indicate that thiosulfate can contribute to H2S signaling under hypoxic conditions and that this is not only a ready source of H2S production but also serves as a means of recycling sulfur and thereby conserving biologically relevant thiols.

Geochemical exploration for gold (Au) is becoming increasingly important to the mining industry. Current processes for Au analyses require sampling materials to be taken from often remote localities. Samples are then transported to a laboratory equipped with suitable analytical facilities, such as Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) or Instrumental Neutron Activation Analysis (INAA). Determining the concentration of Au in samples may take several weeks, leading to long delays in exploration campaigns. Hence, a method for the on-site analysis of Au, such as a biosensor, will greatly benefit the exploration industry. The golTSB genes from Salmonella enterica serovar typhimurium are selectively induced by Au(I/III)-complexes. In the present study, the golTSB operon with a reporter gene, lacZ, was introduced into Escherichia coli. The induction of golTSB::lacZ with Au(I/III)-complexes was tested using a colorimetric β-galactosidase and an electrochemical assay. Measurements of the β-galactosidase activity for concentrations of both Au(I)- and Au(III)-complexes ranging from 0.1 to 5 µM (equivalent to 20 to 1000 ng g(-1) or parts-per-billion (ppb)) were accurately quantified. When testing the ability of the biosensor to detect Au(I/III)-complexes(aq) in the presence of other metal ions (Ag(I), Cu(II), Fe(III), Ni(II), Co(II), Zn, As(III), Pb(II), Sb(III) or Bi(III)), cross-reactivity was observed, i.e. the amount of Au measured was either under- or over-estimated. To assess if the biosensor would work with natural samples, soils with different physiochemical properties were spiked with Au-complexes. Subsequently, a selective extraction using 1 M thiosulfate was applied to extract the Au. The results showed that Au could be measured in these extracts with the same accuracy as ICP-MS (P<0.05). This demonstrates that by combining selective extraction with the biosensor system the concentration of Au can be accurately measured, down to a quantification limit of 20 ppb (0.1 µM) and a detection limit of 2 ppb (0.01 µM).

The susceptibility of the coral-feeding crown-of-thorns starfish Acanthaster planci to disease may provide an avenue with which to effectively control population outbreaks that have caused severe and widespread coral loss in the Indo-Pacific. Injecting thiosulfate-citrate-bile-sucrose (TCBS) agar into A. planci tissues induced a disease characterized by dermal lesions, loss of skin turgor, collapsed spines, and accumulation of mucus on spine tips. Moreover, the symptoms (and presumably the agent) of this disease would spread rapidly intraspecifically, but interspecific transmission (to other species of echinoderms) is yet to be examined. Vibrio rotiferianus, which was previously reported as a pathogen isolated from lesions of experimentally infected A. planci, was also recovered from Linckia guildingi lesions after several days of direct contact with diseased A. planci, demonstrating disease transmission. However, all L. guildingi fully recovered after 31 ± 16 d. Further studies are in progress to understand the ecology of Vibrio infection in A. planci and the potential transmission risk to corals, fishes, and other echinoderms to evaluate whether injections of TCBS could be a viable tool for controlling A. planci outbreaks.

Since the development of the TIE (Toxicity Identification and Evaluation) in 1988 it has been assumed that the capacity of EDTA and sodium thiosulfate to complex some metals, and thus remove their toxicity, can be applied to both freshwater and seawater ecotoxicological tests and the results subsequently interpreted. However, it is now known that there is a wide variability in the extent of this complexation. In this context, the removal of toxicity caused by the presence of Hg(2+), Cd(2+), Cu(2+), Cr(6+), Zn(2+), Ni(2+), Pb(2+), Ag(1+) and Se(2+), through metal complexation by EDTA and sodium thiosulfate, in relation to the performance of embryo-larval tests with the sea urchin Arbacia lixula was investigated. It was observed that EDTA was capable of removing the toxicity of Pb(2+), Zn(2+) and Cu(2+) while sodium thiosulfate only reduced the toxicity of Ag(1+). Compared to the complexation observed in freshwater ecotoxicological tests, the complexing agents used in this study (EDTA and sodium thiosulfate) have a lower capacity to complex metals in the marine ecotoxicological test with A. lixula., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Purpose: The purpose of this study was to find a suitable method of labelling cartilage samples for the measurement of distraction distances in biomechanical testing., Methods: Samples of bovine cartilage were labelled using five different methods: hydroquinone and silver nitrate (AgNO3), potassium permanganate (KMnO4) with sodium thiosulphate (Na2S2O3), India ink, heat, and laser energy. After the labelling, we analysed the cartilage samples with regard to cytotoxity by histochemical staining with ethidiumbromide homodimer (EthD-1) and calcein AM. Furthermore, we tested cartilages labelled with India ink and heat in a T-peel test configuration to analyse possible changes in the mechanical behaviour between marked and unlabelled samples., Results: Only the labelling methods with Indian ink or a heated needle showed acceptable results in the cytotoxity test with regard to labelling persistence, accuracy, and the influence on consistency and viability of the chondrocytes. In the biomechanical T-peel configuration, heat-labelled samples collapsed significantly earlier than unlabelled samples., Conclusion: Labelling bovine cartilage samples with Indian ink in biomechanical testing is a reliable, accurate, inexpensive, and easy-to-perform method. This labelling method influenced neither the biomechanical behaviour nor the viability of the tissue compared to untreated bovine cartilage.

Foam delivery technology (FDT) uses surfactant based foam to immobilize subsurface contaminants in situ. Where traditional approaches are impractical, FDT has the potential to overcome many of the technical challenges facing the remediation of contaminated deep vadose zone environments. However, little is known about the effects these reactive chemicals may have on microorganisms inhabiting the contaminated subsurface. In addition, there are currently no standard assays to assess microbial responses to subsurface remedial treatments while these agents are under development. The objective of this study was to develop a rapid laboratory assay to assess the potential growth inhibition and/or stimulation of microorganisms following exposure to candidate FDT components. Calcium polysulfide (CPS) and several surfactants (i.e. sodium laureth sulfate (SLES), sodium dodecyl sulfate (SDS), cocamidopropyl betaine (CAPB) and NINOL40-CO) have diverse chemistries and are candidate components of FDT. Shewanella oneidensis MR-1 cultures were exposed to a range of concentrations of these chemicals to determine the minimum bactericidal concentration (MBC) and the growth and viability potential of these components. Concentrations of SDS higher than 700 μM were toxic to S. oneidensis MR-1 growth over the course of four days of exposure. The relative acute toxicity order for these compounds was SDS >> CPS >> NINOL 40-CO>SLES≥CAPB. Dose dependent growth decreases (20-100mM) were observed in the CAPB and SLES treated cultures and both CPS and NINOL 40-CO were toxic at all concentrations tested (1.45-7.25 mM CPS). Both SLES (20-100mM) and SDS at lower concentrations (20-500 μM) were stimulatory to S. oneidensis MR-1 indicating a capacity to be used as a carbon source. These studies also identified potentially key component characteristics, such as precipitate formation and oxygen availability, which may prove valuable in assessing the response of subsurface microorganisms. This benchtop system provides a capability to assess adverse microbial-remediation responses and contributes to the development of in situ remedial chemistries before they are deployed in the field., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The effect of ethanol addition on the determination of thiosulfate based on the reduction of Ce(IV) and fluorescence detection of Ce(III) was investigated by flow-injection analysis. It was found that the sensitivity of thiosulfate detection was significantly increased by injecting thiosulfate into a mixed solution of Ce(IV) and ethanol, rather than a solution of Ce(IV) alone. This is probably due to trace amounts of thiosulfate accelerating the rate of reduction of Ce(IV) by ethanol: Ce(IV) is slowly reduced by ethanol in the absence of thiosulfate, and thiosulfate serves as a catalyst to the reduction. The detection limits as S/N = 3 for thiosulfate were very low (10(-9) M level).

A practical, sensitive and environment-benign protocol for the detection of DNA on polyacrylamide gels was described. In this method, the most commonly used formaldehyde-based developer in DNA silver stain, which poses potential hazards to the health of operators, is firstly replaced by vitamin C (Vc) in sodium thiosulfate solution. This allows user-friendly and efficient visualization of DNA that takes about 20 min to complete all the procedures, and provides comparable sensitivity (8 pg of single band) to the most sensitive formaldehyde-based silver staining method developed before.

We assessed histological changes in the tissues of the crown-of-thorns starfish Acanthaster planci (COTS) after injection of thiosulfate-citrate-bile-sucrose agar (TCBS) which was used as a disease inducer (potential outbreak control method), by conventional and scanning electron microscopy. Digestive glands were processed and stained with hematoxylin and eosin to describe the histological architecture of the intestinal epithelium. Subsequently comparison of healthy versus infected tissues and Gram stains were carried out to confirm bacterial occurrence on infected tissues, characterize the structural changes induced by bacterial communities in COTS tissues, and to determine if the histopathological changes of intestinal tissues were consistent with vibrio infection. TCBS injections induced marked epithelial desquamation, hypertrophy and hypersecretion of glandular cells, epithelial cell destruction, pyknosis, reduction of thickness and disorganization of connective tissue and associated nerve plexus, presence of bacterial colonies, irregular eosinophilic foci in glandular cells, brush border disruption, atrophy and detachment of intestinal microvilli and cell debris in the lumen. All these changes were attributed to a fulminating systemic dysbiosis and were consistent with vibrio infections.

This is the first report of the successful induction of a transmissible disease in the coral-eating crown-of-thorns starfish Acanthaster planci (COTS). Injection of thiosulfate-citrate-bile-sucrose agar (TCBS) culture medium into COTS induced a disease characterized by discoloured and necrotic skin, ulcerations, loss of body turgor, accumulation of colourless mucus on many spines especially at their tip, and loss of spines. Blisters on the dorsal integument broke through the skin surface and resulted in large, open sores that exposed the internal organs. Oedema and reddened digestive tissues and destruction of connective fibers were common. Moreover, healthy COTS in contact with these infected animals also displayed signs of disease and died within 24 h. TCBS induced 100% mortality in injected starfish. There was no introduction of new pathogens into the marine environment. TCBS promoted the growth of COTS' naturally occurring Vibrionales to high densities with subsequent symbiont imbalance followed by disease and death.

We study the oxidation dynamics of thiosulfate ions by hydrogen peroxide in the presence of trace amounts of copper(II) using the reaction temperature as a control parameter in a continuous flow stirred tank reactor. The system displays period-doubling, aperodic, and mixed-mode oscillations at different temperatures. We are able to simulate these complex dynamics with a model proposed by Kurin-Csorgei et al. The model suggests that the Cu(2+)-containing term is not essential for the observed oscillations. We find small-amplitude and high-frequency oscillations in the catalyst-free experimental system. The reaction between H(2)O(2) and S(2)O(3)(2-) contains the core mechanism of the H(2)O(2)-S(2)O(3)(2-)-Cu(2+) and H(2)O(2)-S(2)O(3)(2-)-SO(3)(2-) oscillatory systems, while the Cu(2+) and SO(3)(2-) modulate the feedback loops so as to strengthen the oscillatory dynamics.