Isolation, characterization and S2−-oxidation metabolic pathway of a sulfur-oxidizing strain from a black-odor river in Beijing

A single strain capable of efficient S2−-oxidizing was isolated from a black-odor river in Beijing. The single strain was identified as Stenotrophomonas through the physiology and biochemical characteristics as well as the 16S rRNA sequencing experiment. This strain was named as Stenotrophomonas sp.sp3 (strain sp3). The experimental results showed that for the strain sp3 growth and S2− oxidization, the optimal conditions were as follows: 25 °C of temperature, initial pH 7, 2.5 g/L of initial glucose concentration and 1.00 g/L of initial cell concentration. It was found that there were 31 kinds of sulfur oxidation related genes in the strain sp3 through the whole genomic analysis. The results of the transcriptome analysis suggested that the main metabolic pathway of S2− to SO42− was the paracoccus sulfur oxidation process. The bioconversion processes of S2− to S0, S2− to SO32−, S2O32− to S0 and SO32−, and SO32− to SO42− were controlled by hdrA, cysIJ, tst and sox gene, respectively.

Draft Genome Sequences of Sulfurovum spp. TSL1 and TSL6, Two Sulfur-Oxidizing Bacteria Isolated from Marine Sediment

Sulfurovum spp. TSL1 and TSL6 are sulfur-oxidizing chemolithoautotrophic bacteria isolated from the tsunami-launched marine sediment in the Great East Japan earthquake. This announcement describes the draft genome sequences of the two isolates that possess the gene sets for the sulfur oxidation pathway.

Enantiopure ferrocene-1,2-disulfoxides: synthesis and reactivity

The rational use of directed deprotometallation, sulfur oxidation and sulfoxide/lithium exchange allowed the synthesis of enantiopure ferrocene-1,2-disulfoxide derivatives. Not only they represent the first members of this original family, but...

Organic Amendments and Elemental Sulfur Stimulate Microbial Biomass and Sulfur Oxidation in Alkaline Subtropical Soils

Sulfur deficiency arising due to intensive cultivation, use of sulfur free fertilizers and reduction in atmospheric sulfur depositions has become a major issue limiting crop production in many parts of the world. Elemental sulfur could be a good source of available S, but its slow oxidation is a problem for its efficient use as a sulfur fertilizer. Main objective of the study was to assess the effect of organic amendments (OA) and elemental sulfur (ES) on microbial activities, sulfur oxidation and availability in soil. A laboratory incubation experiment was carried out for a 56 days period using two sulfur deficient alkaline soils. Organic amendments (OA), i.e., farmyard manure (FYM), poultry litter (PL) and sugarcane filter cake (SF), were applied (1% w/w) with or without elemental sulfur (ES) at 50 mg kg−1. Application of ES alone or in combination with OA significantly increasedCO2-C evolution, microbial biomass, and enzyme activities in the soils, except dehydrogenase activity (DHA) which was not affected by ES application. Combined application of OA and ES had a more pronounced effect on microbial parameters compared to ES or OA applied alone. Ratios of dehydrogenase activity-to-microbial biomass C and arylsulfatase activity-to-microbial biomass C were high in ES+FYM and ES+SF treatments, respectively. Elemental sulfur got sufficiently oxidized resulting in significant improvement in plant available S. Relatively more ES was distributed into C-bonded-S than ester bonded-S. Increase in sulfur availability in ES+OA amended soils was the combined function of sulfur oxidation and mineralization processes through improved microbial activity.

High Potential for Anaerobic Microbial Sulfur Oxidation in Oil Sands Tailings Ponds

The biogenic production of toxic H2S gas in sulfate-rich oil sands tailings ponds is associated with strong environmental concerns. Beside precipitation into sulfide minerals and chemical re-oxidation, microbial sulfur oxidation may catalyze sulfide re-cycling but potentially contributes to acid rock drainage (ARD) generation. To evaluate the microbial potential for sulfur oxidation, we conducted a microcosm-based pilot study with tailings of an active pond. Incubations were performed under oxic and anoxic conditions, with and without KNO3 as an electron acceptor and thiosulfate as a common substrate for microbial sulfur oxidation. The highest potentials of sulfur oxidation occurred in oxic assays (1.21 mmol L−1 day−1). Under anoxic conditions, rates were significantly lower and dominated by chemical transformation (0.09 mmol L−1 day−1; p < 0.0001). The addition of KNO3 to anoxic incubations increased microbial thiosulfate oxidation 2.5-fold (0.23 mmol L−1 day−1; p = 0.0474), with complete transformation to SO42− coupled to NO3− consumption, pointing to the activity of sulfur-oxidizing bacteria (SOB) under nitrate-reducing conditions. Importantly, in the presence of KNO3, a decrease in sedimentary sulfides was associated with an increase in S0, which indicates the potential for microbially mediated oxidation of sulfide minerals and ARD generation. Furthermore, the comparative analysis of sediments from other anthropogenic aquatic habitats demonstrated high similarities with respect to viable SOB counts and corresponding activity rates.

A Degradable Inverse Vulcanized Copolymer as a Coating Material for Urea Produced under Optimized Conditions

Global enhancement of crop yield is achieved using chemical fertilizers; however, agro-economy is affected due to poor nutrient uptake efficacy (NUE), which also causes environmental pollution. Encapsulating urea granules with hydrophobic material can be one solution. Additionally, the inverse vulcanized copolymer obtained from vegetable oils are a new class of green sulfur-enriched polymer with good biodegradation and better sulfur oxidation potential, but they possess unreacted sulfur, which leads to void generations. In this study, inverse vulcanization reaction conditions to minimize the amount of unreacted sulfur through response surface methodology (RSM) is optimized. The copolymer obtained was then characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). FTIR confirmed the formation of the copolymer, TGA demonstrated that copolymer is thermally stable up to 200 °C temperature, and DSC revealed the sulfur conversion of 82.2% (predicted conversion of 82.37%), which shows the goodness of the model developed to predict the sulfur conversion. To further maximize the sulfur conversion, 5 wt% diisopropenyl benzene (DIB) as a crosslinker is added during synthesis to produce terpolymer. The urea granule is then coated using terpolymer, and the nutrient release longevity of the coated urea is tested in distilled water, which revealed that only 65% of its total nutrient is released after 40 days of incubation. The soil burial of the terpolymer demonstrated its biodegradability, as 26% weight loss happens in 52 days of incubation. Thus, inverse vulcanized terpolymer as a coating material for urea demonstrated far better nutrient release longevity compared with other biopolymers with improved biodegradation; moreover, these copolymers also have potential to improve sulfur oxidation.

Interactions of Gliotoxin with Protein Cysteines

<p>Gliotoxin is a secondary metabolite that is produced by several species of fungi, and is toxic to mammalian cells. It is immunosuppressive, affects antigen presentation by macrophages, and causes apoptosis of some cells. Gliotoxin is an epipolythiodioxopiperazine molecule and contains an internal disulfide bridge that is highly reactive and essential for its toxicity. Suggested mechanisms of action include modification of thiol groups of cysteine residues in target proteins by generating oxidative stress or through covalent modification. The goal of this project was to develop mass spectrometry methods to detect protein modification by gliotoxin. Creatine kinase was used as a model protein. The measured mass of creatine kinase from 45 spectra gave a mean of 42,944 ± 24 which was consistent with the predicted mass of creatine kinase. A tryptic digest of creatine kinase indicated ions consistent with the predicted masses of the four cys-containing peptides including abundant ions at m/z 794, 1130 and 2870 and an ion at low intensity at 4373. The reaction of creatine kinase with gliotoxin showed a time dependent reaction that after 14 h was consistent with formation of a gliotoxin adduct. Reduction of the product with dithiothreitol released creatine kinase. Analysis of the tryptic peptides using MALDI mass spectrometry indicated complex modification of cysteines possibly including formation of a mixed disulfide adduct, intramolecular disulfides of CK, and sulfur oxidation products. Further analysis using the ICAT (isotope-coded affinity tag) method suggested modification of Cys-254 and Cys-283 by gliotoxin. Preliminary experiments examined the effects of gliotoxin on HL-60 cells using ICAT. Proteins of gliotoxin-treated and untreated cells were labeled with Heavy and Light ICAT reagents. Potential ICAT pairs were detected in the mass spectrum as a preliminary search for proteins affected by gliotoxin. The results indicate that ICAT labeling should be an effective strategy for characterization of the protein targets of gliotoxin.</p>

Aqueous system-level processes and prokaryote assemblages in the ferruginous and sulfate-rich bottom waters of a post-mining lake

In the aqueous oligotrophic ecosystem of a post-mining lake (Lake Medard, Czechia), reductive Fe(II) dissolution outpaces sulfide generation from microbial sulfate reduction (MSR), and ferruginous conditions occur without quantitative sulfate depletion. An isotopically constrained estimate of the rates of sulfate reduction (SRR) suggests that despite a high genetic potential, this respiration pathway is limited by the rather low amounts of metabolizable organic carbon. This points to substrate competition exerted by iron and nitrogen respiring prokaryotes. Yet, the microbial succession across the nitrogenous and ferruginous zones of the bottom water column also indicates sustained genetic potential for chemolithotrophic sulfur oxidation. Therefore, our isotopic SRR estimates could be rather portraying high rates of anoxic sulfide oxidation to sulfate, probably accompanied by microbially induced disproportionation of S intermediates. Near and at the anoxic sediment-water interface, vigorous sulfur cycling can be fuelled by ferric and manganic particulate matter and redeposited siderite stocks. Sulfur oxidation and disproportionation then appear to prevent substantial stabilization of iron monosulfides as pyrite but can enable the interstitial precipitation of small proportions of equant microcrystalline gypsum. This latter mineral isotopically fingerprints sulfur oxidation proceeding at near equilibrium with the ambient anoxic waters, whilst authigenic pyrite-sulfur displays a 38 to 27 ‰ isotopic offset from ambient sulfate, suggestive of incomplete MSR and likely reflective also of an open sulfur cycling system. Pyrite-sulfur fractionation decreases with increased reducible reactive iron in the sediment. In the absence of ferruginous coastal zones today, the current water column redox stratification in the post-mining Lake Medard has scientific value for (i) testing emerging hypotheses on how a few interlinked biogeochemical cycles operated in nearshore paleoenvironments during redox transitional states; and (ii) to acquire insight on how similar early diagenetic redox proxy signals developed in sediments affected by analogue transitional states in ancient water columns.

Interactions of Gliotoxin with Protein Cysteines

<p>Gliotoxin is a secondary metabolite that is produced by several species of fungi, and is toxic to mammalian cells. It is immunosuppressive, affects antigen presentation by macrophages, and causes apoptosis of some cells. Gliotoxin is an epipolythiodioxopiperazine molecule and contains an internal disulfide bridge that is highly reactive and essential for its toxicity. Suggested mechanisms of action include modification of thiol groups of cysteine residues in target proteins by generating oxidative stress or through covalent modification. The goal of this project was to develop mass spectrometry methods to detect protein modification by gliotoxin. Creatine kinase was used as a model protein. The measured mass of creatine kinase from 45 spectra gave a mean of 42,944 ± 24 which was consistent with the predicted mass of creatine kinase. A tryptic digest of creatine kinase indicated ions consistent with the predicted masses of the four cys-containing peptides including abundant ions at m/z 794, 1130 and 2870 and an ion at low intensity at 4373. The reaction of creatine kinase with gliotoxin showed a time dependent reaction that after 14 h was consistent with formation of a gliotoxin adduct. Reduction of the product with dithiothreitol released creatine kinase. Analysis of the tryptic peptides using MALDI mass spectrometry indicated complex modification of cysteines possibly including formation of a mixed disulfide adduct, intramolecular disulfides of CK, and sulfur oxidation products. Further analysis using the ICAT (isotope-coded affinity tag) method suggested modification of Cys-254 and Cys-283 by gliotoxin. Preliminary experiments examined the effects of gliotoxin on HL-60 cells using ICAT. Proteins of gliotoxin-treated and untreated cells were labeled with Heavy and Light ICAT reagents. Potential ICAT pairs were detected in the mass spectrum as a preliminary search for proteins affected by gliotoxin. The results indicate that ICAT labeling should be an effective strategy for characterization of the protein targets of gliotoxin.</p>