H2S Production Rate Research Articles

Hydrogen sulfide attenuates the pathogenesis of pulmonary fibrosis induced by bleomycin in rats

The present study investigated the role of the endogenous cystathionine gamma-lyase (CSE) / hydrogen sulfide pathway in the pathogenesis of pulmonary fibrosis. Rats treated with intratracheal bleomycin were exposed either to the H2S donor NaHS or to saline. The results on day 7 showed that plasma H2S concentration and pulmonary CSE activity (H2S production rate) were significantly lower in rats treated with bleomycin and saline (fibrosis-alone) than in controls, whereas on day 28 plasma H2S concentration was higher and pulmonary CSE activity was the same as that of controls. The relative CSE mRNA level in the lungs of rats treated with bleomycin was significantly higher than control values on days 7 and 28. After exposure to NaHS, the total lung hydroxyproline content and the malondialdehyde (MDA) content were both significantly lower, with no difference observed between NaHS high-dose and low-dose treatments. Further, MDA formation stimulated by the free radical-generating system (FRGS) in vitro was lower in lung tissue incubated with NaHS than it was in tissue incubated with FRGS alone. These results suggest that NaHS administration ameliorated the pulmonary fibrosis induced by bleomycin in rats and that this protective effect of H2S may be mediated by its antioxidative action.

Regulatory Effect of Hydrogen Sulfide on Vascular Collagen Content in Spontaneously Hypertensive Rats

The present study aimed to examine the regulatory effect of hydrogen sulfide (H2S) on vascular collagen remodeling in hypertensive rats. After 5 weeks of H2S donor treatment, tail blood pressure, the endogenous H2S production rate, levels of hydroxyproline and collagen type I, collagen type I protein expression in the thoracic aorta, [3H]thymidine ([3H]TdR) incorporation, [3H]proline incorporation, and [3H]hydroxyproline secretion in cultured vascular smooth muscle cells (VSMCs) were measured. We also examined the effects of NaHS on angiotensin II-induced mitogen-activated protein kinase (MAPK) activation and angiotensin II type 1 (AT1) receptor binding affinity. Vascular hydroxyproline and collagen type I levels were high, and collagen type I immunohistochemical staining in the thoracic aorta was strong in SHRs compared to Wistar Kyoto (WKY) rats. [3H]TdR and [3H]proline incorporation and [3H]hydroxyproline secretion were also higher in cultured VSMCs from SHR than those from WKY rats. However, vascular H2S production was lower in SHR compared with WKY rats. Treatment with NaHS increased vascular H2S production in SHRs, and partly reversed the changes in [3H]TdR and [3H]proline incorporation and [3H]hydroxyproline secretion. In cultured VSMCs, [3H]TdR and [3H]proline incorporation stimulated by angiotensin II was inhibited by incubation with NaHS. The inhibitory effect of NaHS on VSMC proliferation and collagen generation was stronger in the SHR than in the WKY group. Moreover, NaHS could dose-dependently decrease angiotensin II-induced MAPK activation. NaHS also decreased AT1 receptor binding as well as the binding affinity of the AT1 receptor. Thus, in SHRs, which demonstrated vascular remodeling and collagen accumulation, the endogenous H2S pathway is involved in the regulation of excess vascular collagen.

Prediction of Hydrogen Sulphide Production in SAGD Projects

Abstract The production of hydrogen sulphide and carbon dioxide is a feature common to all SAGD projects. Both gases are formed by a chemical reaction of steam condensate with bitumen in the SAGD steam zone in Athabasca; they are not normally present as solution gases. The production rates of these gases are therefore strongly dependent on operating characteristics of individual projects, primarily the steam pressure. The potential need for sulphur recovery plants in the larger SAGD project expansions creates the need for first order predictions of H2S production rates, so that appropriate sulphur recovery technologies can be identified. A simple method for the prediction of hydrogen sulphide production has been derived, such that, for most Athabasca projects in the 180 to 240 ºC range of steam zone temperatures, a probable production rate estimate can be read off a simple graph. The graph is built from laboratory data on aquathermolysis, first provided by Hyne, and the assumption of pseudo-zero order kinetics of the aquathermolysis reaction that generates hydrogen sulphide. A temperature dependency is predicted, and is confirmed by field measurements of projects in the 180 to 240 ºC range. Introduction The solvolytic reaction of Athabasca bitumen with steam condensate has been observed since the earliest days of piloting the recovery of this bitumen resource. The first laboratory studies were performed by Hyne et al.(1–3), who coined the now widely-used term "aquathermolysis". More detailed mechanistic studies followed from Hyne's group, and also from the group led by Strausz at the University of Alberta(4). The quantitative aspect of Hyne's work has been largely ignored, possibly because his work was, for the most part, done at 240 ºC steam temperatures, whereas the steam zone temperatures in SAGD pilots and commercial operations have varied from that. Obviously, the steam zone temperature must have an effect on production of the acid gases because the kinetics of generation are temperature dependent. A previously published method of estimating hydrogen sulphide production in SAGD is provided by the method of Thimm(5), which is based on the Henry's Law behaviour of gases in a SAGD steam zone. That method is capable of prediction of produced gas and steam zone gas compositions over time, including situations where the steam zone pressure changes or where gas is injected. However, it involves relatively lengthy computations in solution thermodynamics. For the purpose of identifying potential sulphur recovery technologies, a quicker method of estimating hydrogen sulphide production is required; at least, as an approximate guide. Moreover, it would be useful to express the hydrogen sulphide production on a mass or volume per unit bitumen basis to provide a simple guide for expansion planning. Reaction Order Although neither Hyne nor Strausz have published a reaction order, the following considerations suggest a zero order reaction in the SAGD steam zone. Consider that one might expect a reaction rate equation of the type: (1) rate = k [ sulphur ] [ steam condensate ] where the concentrations may be expressed in terms of various terms suitable for reservoir engineering.

H2S, Endoplasmic Reticulum Stress, and Apoptosis of Insulin-secreting Beta Cells

Cystathionine gamma-lyase (CSE) is a key enzyme in the trans-sulfuration pathway, which uses L-cysteine to produce hydrogen sulfide (H2S). Functional changes of pancreatic beta cells induced by endogenous H2S have been reported, but the effect of the CSE/H2S system on pancreatic beta cell survival has not been known. In this study, we demonstrate that H2Sat physiologically relevant concentrations induced apoptosis of INS-1E cells, an insulin-secreting beta cell line. Transfection of INS-1E cells with a recombinant defective adenovirus containing the CSE gene (Ad-CSE) resulted in a significant increase in CSE expression and H2S production. Ad-CSE transfection also stimulated apoptosis. The other two end products of CSE-catalyzed enzymatic reaction, ammonium and pyruvate, had no effects on INS-1E cell apoptosis, indicating that overexpression of CSE may stimulate INS-1E cell apoptosis via increased endogenous production of H2S. Both exogenous H2S (100 microM) and Ad-CSE transfection inhibited ERK1/2 but activated p38 MAPK. Interestingly, BiP and CHOP, two indicators of endoplasmic reticulum (ER) stress, were up-regulated in H2S-and CSE-mediated apoptosis in INS-1E cells. After suppressing CHOP mRNA expression, H2S-induced apoptosis of INS-1E cells was significantly decreased. Inhibition of p38 MAPK, but not of ERK1/2, inhibited the expression of BiP and CHOP and decreased H2S-stimulated apoptosis, suggesting that p38 MAPK activation functions upstream of ER stress to initiate H2S-induced apoptosis. It is concluded that H2S induces apoptosis of insulin-secreting beta cells by enhancing ER stress via p38 MAPK activation. Our findings may help unmask a novel role of CSE/H2S system in regulating pancreatic functions under physiological condition and in diabetes.

Cystathionine γ-Lyase Overexpression Inhibits Cell Proliferation via a H2S-dependent Modulation of ERK1/2 Phosphorylation and p21Cip/WAK-1

Cystathionine gamma-lyase (CSE) is a key enzyme in the trans-sulfuration pathway. CSE uses L-cysteine as a substrate to produce hydrogen sulfide (H2S). The CSE/H2S system has been shown to play an important role in regulating cellular functions in different systems. In the present study, we used CSE stably overexpressed HEK-293 cells to explore the effect of the CSE/H2S system on cell growth and proliferation. The overexpression of CSE resulted in increases in CSE mRNA levels, CSE proteins, and intracellular H2S production rates, as well as the inhibition of cell proliferation and DNA synthesis. These effects were accompanied by a sustained ERK activation and up-regulation of the cyclin-dependent kinase inhibitor p21Cip/WAK-1. Blocking the action of ERK with U0126 inhibited the induction of p21Cip/WAK-1, suggesting that ERK activation functions upstream of p21Cip/WAK-1 activation to initiate the CSE overexpression-induced cell growth inhibition. The antiproliferative effect of CSE is likely mediated by endogenously produced H2S because the H2S scavenger methemoglobin (10 microm) significantly decreased the H2S production rate and reversed the antiproliferative effect afforded by CSE. Exogenous H2S (100 microm) also inhibited cell proliferation. However, the other CSE-catalyzed products, ammonium and pyruvate, failed to inhibit cell proliferation. Methemoglobin also abolished the inhibitory effect of exogenous H2S on cell proliferation. Moreover, exogenous H2S induced a sustained ERK and p21Cip/WAK-1 activation. These findings support the hypothesis that endogenously produced H2S may play a fundamental role in cell proliferation and survival.

Mass‐transport dynamics, activity, and structure of sulfate‐reducing biofilms

AbstractFactors limiting hydrogen sulfide production were identified in a two‐species biofilm containing sulfate‐reducing bacteria (Desulfovibrio desulfuricans) and nonsulfate‐reducing bacteria (Pseudomonas fluorescens). Profiles of hydrogen sulfide (H2S) concentration, pH, local mass‐transport coefficient, local flow velocity, and local relative effective diffusivity in the biofilm were measured using microelectrodes. Biofilms had a heterogeneous structure consisting of cell clusters separated by voids. Typically, the H2S concentration was lower in the voids than in the adjacent cell clusters, demonstrating that the voids acted as transport channels for removing H2S from cell clusters. The extent of biofilm heterogeneity was directly correlated with the flux of H2S from cell clusters. At flow velocities below 2 cm/s, the flux of H2S from cell clusters depended on the flow velocity. We concluded that at these flow velocities the H2S production rate was limited by the delivery rate of sulfate ions to the biofilm. At flow velocities above 2 cm/s, the H2S production rate was nearly constant and did not depend on the flow velocity. At high flow velocities (>2 cm/s) the H2S production rate was limited by metabolic reactions in the biofilm. Local intrabiofilm flow velocity profiles were influenced strongly by biofilm heterogeneity without significant pH variation within biofilms. Surprisingly, profiles of local relative effective diffusivity indicated that the biofilm was made up of two layers, which could be related to the specimen with a two‐species biofilm.

The relationship between microbial metabolic activity and biocorrosion of carbon steel

The effect of metabolic activity (expressed by generation time, rate of H2S production and the activity of hydrogenase and adenosine phosphosulphate (APS)-reductase enzymes) of the 8 wild strains of Desulfovibrio desulfuricans and of their resistance to metal ions (Hg2+, Cu2+, Mn2+, Zn2+, Ni2+, Cr3+) on the rate of corrosion of carbon steel was studied. The medium containing lactate as the carbon source and sulphate as the electron acceptor was used for bacterial metabolic activity examination and in corrosive assays. Bacterial growth inhibition by metal ions was investigated in the sulphate-free medium. The rate of H2S production was approximately directly proportional to the specific activities of the investigated enzymes. These activities were inversely proportional to the generation time. The rate of microbiologically induced corrosion (MIC) of carbon steel was directly proportional to bacterial resistance to metal ions (correlation coefficient r = 0.95). The correlation between the MIC rate and the activity of enzymes tested, although weaker, was also observed (r = 0.41 for APS-reductase; r = 0.69 for hydrogenase; critical value rc = 0.30, p = 0.05, n = 40).

Kinetic investigation of microbial souring in porous media using microbial consortia from oil reservoirs

Microbial souring (H2S production) in porous media was investigated in an anaerobic upflow porous media reactor at 60 degrees C using microbial consortia obtained from oil reservoirs. Multiple carbon sources (formate, acetate, propionate, iso- and n-butyrates) found in reservoir waters as well as sulfate as the electron acceptor was used. Kinetics and rates of souring in the reactor system were analyzed. Higher volumetric substrate consumption rates (organic acids and sulfate) and a higher volumetric H(2)S production rate were found at the from part of the reactor column after H(2)S production had stabilized. Concentration gradients for the substrates (organic acids and sulfate) and H(2)S were generated along the column. Biomass accumulation throughout the entire column was observed. The average specific sulfate reduction rate (H(2)S production rate) in the present reactor after H(2)S production had stabilized was calculated to be 11062 +/-2.22 mg sulfate-S/day g biomass.

Propionate-driven sulphate-reduction by oil-field bacteria in a pressurised porous rock bioreactor

The occurrence of high concentrations (up to 4900 mg/l) of anions of acetic, propionic and butyric acids in co-produced water from oil reservoirs represents a large pool of potential electron donors for bacterial sulphate reduction. Enrichment cultures in defined media, isolated from a variety of oil-filed environments demonstrated the wide distribution of acetate-and propionate-utilising sulphate-reducing bacteria (SRB). A propionate-utilising enrichment culture consisting predominantly of SRB, tentatively identified as species of Desulfobulbus, was used to inoculate a pressurised porous rack bioreator operating under simulated reservoir conditions. Using a flood velocity of 6.3 cm/h with an inlet propionate concentration of 168 mg/l, a sulphide generation rate of 2.5 μg/ml of rock per hour was achieved at 30° C and 20 MPa. This rate indicates that a sphere of reservoir rock 9.3 m in radius, colonised with propionate-utilising SRB, could produce 50 kg sulphide day. The rates of propionate-driven bacterial sulphate reduction observed in the porous rock bioreactor could sustain the H2S production rates observed from wells in souring reservoirs.

Microbial Corrosion of Concrete Sewer Pipes, H2S Production from Sediments and Determination of Corrosion Rate

Little slime layer was found to exist on the walls of sewer pipes in an anaerobic condition when the sewage flow rate was higher than approximately 30 cm/sec. Therefore, H2S is not produced from slime layers but from sediments which existed in the main trunk or the pressure main. The H2S production rates ranged from 5.5 to 64 pg-H2S/g·solid h depending on the contents of organic compounds and the cell numbers of sulfate reducing bacteria (SRB). The limiting nutrients are assumed to be fatty acids by the spike test. The pipe wall in the area just above the sewage level corroded severely, but the crown of the pipe was not heavily corroded. The corrosion rate of the concrete sewer pipe at the Ohmuta treatment plant was 4.3 to 4.7 mm/y in the area just above the sewage level and 1.9 mm/y at the crown. The experiments using mortar as a test specimen showed that the corrosion rate usually ranged from 3.7 to 7.7 ram per year. But an extremely high corrosion rate was observed when the mortar was placed on the stage of the manhole of the pipe at Ohmuta Treatment Plant at temperatures of 25 to 30°C and H2S concentrations of 3 to 400 ppm. Corroded materials found on the surface of the pipe wall and mortar specimens were gypsum at low pH. Ettringite appeared within cracks of the mortar specimens at high pH.

Hydrogen Sulphhide Production from Sulphite by Saccharomyces cerevisiae

In a medium containing sulphite and sulphate, Saccharomyces cerevisiae TC8 produced H2S from sulphite but not from sulphate which, under these conditions, was not taken up. Production of H2S started with the onset of the stationary phase of growth, and both were triggered by the depletion of ammonium ions or the addition of cycloheximide to cultures. Addition of ammonium sulphate to stationary-phase cultures stopped H2S production and stimulated growth. Inclusion of 1 mhl-methionine in the medium halved the rate of H2S production, while lowering the concentration of sulphite also decreased the rate of production. Sulphite from a pyruvate-sulphite complex was also metabolized to give H2S. Maximum rates of H2S production, induced by including different concentrations of ammonium ions in the medium or by adding cycloheximide to cultures, closely correlated with the sulphite reductase activity in extracts of organisms.

Model of Biological and Diffusional Processes Involving Hydrogen Sulfide in a Marine Microcosm

A model was constructed to describe the short term changes in hydrogen sulfide concentration at 1 mm intervals in an anoxic, organically rich marine sediment, during dark and illuminated periods. The parameter values which gave the closest simulation of the experimental results were as follows: the turnover rate constant for the H2S pool at the surface, due to photosynthetic oxidation, was 50-100 h-I; the rate of H2S production had little discernible effect over a range of 0.01 to 1.0 imol cm-3 h-1; the apparent diffusion coefficient was very important and was approximately 0.1 cm2 h-1 (2.8 x 105 cm2 s-1) but probably included factors other than pure molecular diffusion. The very rapid reappearance of H2S in the surface layer, in the dark following a short period of depletion due to illumination, was most probably accounted for by diffusional processes.

DECOMPOSITION OF SOME ORGANIC SULFUR COMPOUNDS IN PETROLEUM BY ANAEROBIC BACTERIA

Four kinds of bacterial cultures, which produce H2S from organic sulfur compounds such as thiophene, dimethyl sulfide, 1-butanethiol, polysulfides, as well as from crude oil, residue oil, and asphaltene, were isolated from sludges collected from oil well or reservoir bottom of crude oil. The culture which decomposes thiophene contained bacterial cells which are gram-negative and of rod shape with average dimension of 3×0.5μ. The bacteria grow optimally at pH 7.2-7.8 and at 38° in N2 or H2. Polypeptone is essential for their growth, and addition of FePO4 increases the rate of H2S production. The cell-free extract of thiophene-decomposing bacteria catalyzes the production of H2S from thiophene in the presence of methyl viologen in H2.

Studies of the Sulphate Reducing Bacteria, Isolated from the Black Bottom-mud of Brackish Waters. I

(1) Organism which can produce sulphuretted hydrogen from sulphates, Spirillurm desulfuricans var., was isolated from the black bottom-mud of the lakes of Mikata, Hukui Pref., communicating with the Japan Sea. (2) Through the action of the organisms isolated, sulphuretted hydrogen is formed from sulphates, obeying the law of mono-molecular auto-catalytic reaction. (3) The activity of the micro-organisms is influenced by the temperature of medium, the rate of H2S production and the temperature being governed by ARRUENIUS' law, with Q10=3.5. (4) The initial pH-value of the medium, in the range of 5•8 ?? 7•8, has no effect on the activity in question.