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1.
P. MALLE M. VALLE P. EB R. TAILLIEZ 《Journal of Rapid Methods and Automation in Microbiology》1998,6(2):129-141
H2 S bacteria of seafish flesh are weakly halophilic and require on average 1.68% NaCl according to statistical studies. Enumeration is optimal on PCA-H2 S(a PCA medium supplemented with sulfur sources and increased NaCl concentrations) incubated at 25C. Total aerobic bacteria can be counted simultaneously on this medium. The proportion of H2 S bacteria relative to total aerobic bacteria increased slightly during prolonged storage of the fish, but was highly variable. Models relating H2 S bacterial counts to spoilage of fish are sigmoidal and showed that when the count exceeds 10,000 CFU/g, whole or filleted fish stored in ice at 0C are unfit for consumption. Shewanella putrefaciens accounted for 69% of the H2 S bacteria at the fifth day of storage and 100% at the fifteenth. 相似文献
2.
Hydrogen sulfide (H2 S) is a well known and pungent toxic gas that has recently been shown to be synthesised in man from the amino acids cystathionine, homocysteine and cysteine by at least two distinct enzymes; cystathionine-γ-lyase and cystathionine-β-synthase. In the past few years, H2 S has emerged as a novel and increasingly important mediator in the cardiovascular system but delineating the precise physiology and pathophysiology of H2 S is proving to be complex and difficult to unravel with disparate findings reported with cell types, tissue types and animal species reported. Therefore, in this review we summarize the mechanisms by which H2 S has been proposed to regulate blood pressure and cardiac function, discuss the mechanistic discrepancies reported in the literature as well as the therapeutic potential of H2 S. We also examine the methods of H2 S detection in biological fluids, processes for H2 S removal and discuss the reported blood levels of H2 S in man and animal models of cardiovascular pathology. We also highlight the complex interaction of H2 S with nitric oxide in regulating cardiovascular function in health and disease. 相似文献
3.
Isotope effects associated with the anaerobic oxidation of sulfide by the purple photosynthetic bacterium, Chromatium vinosum 总被引:2,自引:0,他引:2
Abstract Small inverse isotope effects of 1–3‰ were consistently observed for the oxidation of sulfide to elemental sulfur during anaerobic photometabolism by Chromatium vinosum . The inverse fractionation can be accounted for by an equilibrium isotope effect between H2 S and HS− , and may indicate that C. vinosum (and other photosynthetic bacteria) utilizes H2 S rather than HS− as the substrate during sulfide oxidation. 相似文献
4.
The effect of short-term H2 S fumigation on water-soluble sulphydryl and glutathione levels in spinach 总被引:2,自引:0,他引:2
Abstract. Short-term fumigation of Spinacia oleracea with 380 μg m−3 H2 S (250 ppb) resulted in a rapid accumulation of water-soluble SH-compounds in the shoots. After 1 h exposure a substantial increase in the SH-content was already detectable and maximal accumulation, three- to four-fold that in control plants, was observed after 24 h of exposure. Irradiation during H2 S exposure only slightly affected the rate and level of SH-accumulation. H2 S fumigation did not affect the water-soluble SH-content of the roots. Glutathione was the sole water-soluble SH-compound accumulating upon exposure to H2 S. It was calculated that during the first hour of exposure to 380 μg m−3 H2 S 39% of the possible absorbed H2 S was converted into glutathione. The SH-content of the water-soluble proteins of the shoots was not affected by H2 S exposure. When fumigation was stopped, a rapid decrease in glutathione content was observed and after 48 h the content was comparable to that of the control plants. Contrary to H2 S, SO2 fumigation did not result in a rapid accumulation of glutathione in spinach shoots. The possible role of glutathione accumulation during H2 S fumigation is discussed. 相似文献
5.
Endosymbiotic Methanogenic Bacteria In Anaerobic Ciliates: Significance For the Growth Efficiency of the Host 总被引:2,自引:0,他引:2
ABSTRACT Endosymbiotic methanogenic bacteria of three species of anaerobic ciliates (Plagiopyla frontata, Metopus conforms , and M. palaeformis) were inactivated with the specific methanogen inhibitor 2-bromoethanesulfonic acid. the absence of endosymbiont methanogens reduced growth rate and growth yield by about 30% in P. frontata and M. contortus , while no significant change in fitness was observed in M. palaeformis. In Plagiopyla the growth rate constant is not affected by an artificially increased pH2 neither in normal nor in methanogen-free ciliates. the energetic advantage conferred by endosymbiont methanogens in Plagiopyla and in Metopus contortus probably is due to excretion of organic material from the bacteria at the expense of bacterial reproduction. It is unlikely that the maintenance of a low pH2 within the cells due to H2 -consumption by the bacteria is important to the ciliates. 相似文献
6.
Competition for sulfide among colorless and purple sulfur bacteria in cyanobacterial mats 总被引:7,自引:0,他引:7
Abstract The vertical zonation of light, O2 , H2 S, pH, and sulfur bacteria was studied in two benthic cyanobacterial mats from hypersaline ponds at Guerrero Negro, baja California, Mexico. The physical-chemical gradients were analyzed in the upper few mm at ≥ 100 μm spatial resolution by microelectrodes and by a fiber optic microprobe. In mats, where oxygen produced by photosynthesis diffused far below the depth of the photic zone, colorless sulfur bacteria ( Beggiatoa sp.) were the dominant sulfide oxidizing organisms. In a mat, where the O2 –H2 S interface was close to the photic zone, but yet received no significant visible light, purple sulfur bacteria ( Chromatium sp.) were the dominant sulfide oxidizers. Analysis of the spectral light distribution heare showed that the penetration of only 1% of the incident near-IR light (800–900 nm) into the sulfide zone was sufficient for the development of Chromatium in a narrow band of 300 μm thickness. The balance betweem O2 and light penetration down into the sulfide zone thus deterined in mcro-scale which type of sulfur bacteria becamed dominant. 相似文献
7.
Plant responses to H2 S and SO2 fumigation. II. Differences in metabolism of H2 S and SO2 in spinach 总被引:1,自引:0,他引:1
Frank M. Maas Luit J. de Kok Willy Strik-Timmer Pieter J. C. Kuiper 《Physiologia plantarum》1987,70(4):722-728
Fumigation of spinach (Spinacia oleracea L. cvs Estivato and Monosa) with H2 S or SO, for 1 to 6 days resulted in accumulation of sulfhydryl (SH) compounds in the shoots of both H2 S- and SO2 -exposed plants. The sulfate concentration in shoots of SO2 -exposed plants increased linearly with time. SH accumulation showed saturation kinetics as a function of time as well as H2 S concentration, ascribed to the internal H2 S concentration in the plant and the availability of substrates for glutathione synthesis, respectively. SH compounds accumulated more at lower exposure temperatures, whereas sulfate accumulation was more pronounced at higher temperatures. These results are discussed in relation to the possible foliar uptake of H2 S and SO2 , the temperature dependence of uptake and the water solubility of these gases. The possibility of SO2 -induced H2 S emission rather than sulfate accumulation as a source for SH accumulation is also discussed. Cessation of fumigation resulted in a decrease in SH compounds and sulfate content that could be accounted for by sulfur metabolism and growth, respectively. 相似文献
8.
Incubation of oat ( Avena sativa L. cv. Victory) coleoptile segments in 4 m M L-cysteine reduced the tissue ATP level to 42 nmol ( g fresh weight)−1 (35% of normal) over a 2 h period. Emissions of H2 S accompanied this depletion in ATP suggesting an H2 S production by desulfhydration of cysteine similar to that reported in other plants. Additions of exogenous H2 S to the sections also caused ATP depletion. Aminooxyacetate, an inhibitor of cysteine desulfhydrase (EC 4.4.1.1), eliminated the cysteine-induced H2 S emission and the ATP depletion. Prolonged exposure to cysteine depressed the electrical polarity of the cell membrane from – 116 mV to –85 mV. That and other electrical responses appear to reflect a reduced capacity for ATP-dependent H+ extrusion. These effects should be taken into account whenever cysteine is used in physiological experiments. 相似文献
9.
10.
SUMMARY: Sterilized raw sewage sludge enriched with sulphate and inoculated with pure strains of Desulphovibrio desulphuricans produced negligible sulphide. Unsterilized sludge supplemented with 7% (w/v) CaSO4 .2H2 O and inoculated with crude cultures of sulphate-reducing bacteria obtained from sewage yielded 1·0% S2- (wt S2- produced as H2 S/vol. of raw sludge) in 6 months at 30°. By repeated subculture more active cultures developed which produced 1% S2- in 7 days and 1·2–1·9% in 28 days. Digested sludge yielded only 0·1% S2- . In semicontinuous fermentations at 30°, raw sludge without added sulphate produced 20 times its own volume of gas containing 70% CH4 and 30% CO2 . When 5% CaSO4 .2H2 O and an active crude culture of sulphate reducers were added, gas production decreased steadily to zero. There were no differences in pH, temperature and redox potential in sludges producing methane or sulphide. The chief cause of inhibition appeared to be the action of sulphide: 0·02% soluble sulphide (S2- ) totally inhibited methane formation; 0·01% S2- initially decreased gas production by one-quarter but there was a slow recovery to normal, suggesting acclimatization of the methane-producing organisms to sulphide.
Linked fermentations, in which gas from a methane fermentation swept H2 S from a sulphide fermentation, gave a final gas mixture of about 60% CH4 , 30% CO2 and 5–10% H2 S. The yield of sulphide depended on the rate of sweeping. 相似文献
Linked fermentations, in which gas from a methane fermentation swept H
11.
Linden DR Sha L Mazzone A Stoltz GJ Bernard CE Furne JK Levitt MD Farrugia G Szurszewski JH 《Journal of neurochemistry》2008,106(4):1577-1585
The gaseous molecule hydrogen sulfide (H2 S) has been proposed as an endogenous signal molecule and neuromodulator in mammals. Using a newly developed method, we report here for the first time the ability of intact and living brain and colonic tissue in the mouse to generate and release H2 S. This production occurs through the activity of two enzymes, cystathionine-γ-lyase and cystathionine-β-synthase. The quantitative expression of messenger RNA and protein localization for both enzymes are described in the liver, brain, and colon. Expression levels of the enzymes vary between tissues and are differentially distributed. The observation that, tissues that respond to exogenously applied H2 S can endogenously generate the gas, strongly supports its role as an endogenous signal molecule. 相似文献
12.
Treatment of pancreatic acinar cells by hydrogen sulphide has been shown to induce apoptosis. However, a potential role of mitogen-activated protein kinases (MAPKs) in this apoptotic pathway remains unknown. The present study examined the role of MAPKs in H2 S-induced apoptosis in mouse pancreatic acinar cells. Pancreatic acinar cells were treated with 10 μM NaHS (a donor of H2 S) for 3 hrs. For the evaluation of the role of MAPKs, PD98059, SP600125 and SB203580 were used as MAPKs inhibitors for ERK1/2, JNK1/2 and p38 MAPK, respectively. We observed activation of ERK1/2, JNK1/2 and p38 when pancreatic acini were exposed to H2 S. Moreover, H2 S-induced ERK1/2, JNK1/2 and p38 activation were blocked by pre-treatment with their corresponding inhibitor in a dose-dependent manner. H2 S-induced apoptosis led to an increase in caspase 3 activity and this activity was attenuated when caspase 3 inhibitor were used. Also, the cleavage of caspase 3 correlated with that of poly-(ADP-ribose)-polymerase (PARP) cleavage. H2 S treatment induced the release of cytochrome c , smac from mitochondria into the cytoplasm, translocation of Bax into mitochondria and decreased the protein level of Bcl-2. Inhibition of ERK1/2 using PD98059 caused further enhancement of apoptosis as evidenced by annexin V staining, while SP600125 and SB203580 abrogated H2 S-induced apoptosis. Taken together, the data suggest that activation of ERKs promotes cell survival, whereas activation of JNKs and p38 MAP kinase leads to H2 S-induced apoptosis. 相似文献
13.
Abstract Spore-forming sulfate-reducing bacteria (SRB) were enriched selectively from various kinds of aerobic soils with fatty acids as the sole carbon and energy source. A Gram-negative motile rod-shaped bacterium, which produced gas vacuoles during sporulation was isolated. It degraded alcohols, aromatic and n-fatty acids (up to C18 ) except for propionate, completely to CO2 . Sulfate, sulfite, thiosulfate or elemental sulfur served as electron acceptors. Because of its sensitivity to H2 S, the isolate never produced more than 8 mM dissolved sulfide at pH 7.0. G + C-content of the DNA was 48.0 mol %. The isolated strain Pato is described as a new species Desulfotomaculum sapomandens . 相似文献
14.
A mathematical model of syntrophic cocultures in the chemostat 总被引:1,自引:0,他引:1
Abstract A model is presented for syntrophic associations between H2 -producing acetogenic bacteria and H2 -utilizing bacteria. A growth rate expression different from the usual Monod equation is applied to the H2 -producing acetogenic bacterium to take into account the thermodynamics of the metabolic reaction involved as dominant factor. The steady of states of the model system are given as branches in a bifurcation diagram. Numerical experiments on the stability of the branches and on the influence of different values in model parameters are performed. The predictions of our model are discussed with regard to the results obtained from experiments with syntrophic cocultures of different species of H2 -producing acetogenic bacteria in combination with H2 -consuming bacteria. 相似文献
15.
Antonio G. Cordente Anthony Heinrich Isak S. Pretorius & Jan H. Swiegers 《FEMS yeast research》2009,9(3):446-459
The production of hydrogen sulfide (H2 S) during fermentation is a common and significant problem in the global wine industry as it imparts undesirable off-flavors at low concentrations. The yeast Saccharomyces cerevisiae plays a crucial role in the production of volatile sulfur compounds in wine. In this respect, H2 S is a necessary intermediate in the assimilation of sulfur by yeast through the sulfate reduction sequence with the key enzyme being sulfite reductase. In this study, we used a classical mutagenesis method to develop and isolate a series of strains, derived from a commercial diploid wine yeast (PDM), which showed a drastic reduction in H2 S production in both synthetic and grape juice fermentations. Specific mutations in the MET10 and MET5 genes, which encode the catalytic α- and β-subunits of the sulfite reductase enzyme, respectively, were identified in six of the isolated strains. Fermentations with these strains indicated that, in comparison with the parent strain, H2 S production was reduced by 50–99%, depending on the strain. Further analysis of the wines made with the selected strains indicated that basic chemical parameters were similar to the parent strain except for total sulfite production, which was much higher in some of the mutant strains. 相似文献
16.
Some rumen ciliates have endosymbiotic methanogens 总被引:16,自引:0,他引:16
Bland J. Finlay Genoveva Esteban Ken J. Clarke Alan G. Williams T.Martin Embley Robert P. Hirt 《FEMS microbiology letters》1994,117(2):157-161
Abstract Most of the small ciliate protozoa, including Dasytricha ruminantium and Entodinium spp. living in the rumen of sheep, were found to have intracellular bacteria. These bacteria were not present in digestive vacuoles. They showed characteristic coenzyme F420 autofluorescence and they were detected with a rhodamine-labelled Archaea-specific oligonucleotide probe. The measured volume percent of autofluorescing bacteria (1%) was close to the total volume of intracellular bacteria estimated from TEM stereology. Thus it is likely that all of the bacteria living in the cytoplasm of these ciliates were endosymbiotic methanogens, using H2 evolved by the host ciliate to form methane. Intracellular methanogens appear to be much more numerous than those attached to the external cell surface of ciliates. 相似文献
17.
Abstract Freshly isolated soil bacteria were screened for different characteristics of the H2 metabolism without prior selection for growth on H2 . The bacteria were isolated from different grain size fractions of a neutral meadow cambisol and an acidic forest cambisol, and then tested (1) for the ability to oxidize H2 , (2) for chemolithoautotrophic growth on H2 as sole electron donor and energy source, (3) for DNA-DNA-hybridization with two hydrogenase gene fragments from Alcaligenes eutrophus and Rhizobium leguminosarum , and (4) for reduction of 2,3,5-triphenyl-2H-tetrazoliumchloride (TTC) in the presence of H2 . Many (65–90%) of the isolates were able to reduce TTC, but only 30–65% were actually able to oxidize H2 indicating that the TTC test was not a specific characteristic for H2 oxidation ability. The TTC test was only reliable in pure cultures of known bacteria with optimized test conditions, here shown for Alcaligenes eutrophus, Bradyrhizobium japonicum and Nocardia opaca , but not in mixed cultures of unknown bacteria. Still less (< 30%) of the isolates were able to grow chemolithoautotrophically indicating that culturable aerobic bacteria with the ability for H2 oxidation are more abundant than bacteria with the ability for chemolithoautotrophic growth. The DNA-DNA-hybridization test failed to detect many of the bacteria with H2 oxidation activity, probably since the hydrogenase genes present in the isolates were too diverse to be all detected by the DNA probes applied. 相似文献
18.
Michael W.W. Adams 《FEMS microbiology reviews》1994,15(2-3):261-277
Abstract: Hyperthermophiles are a recently discovered group of microorganisms that grow at and above 90°C. They currently comprise over 20 different genera, and except for two novel bacteria, all are classified as Archaea. The majority of these organisms are obligately anaerobic heterotrophs that reduce elemental sulfur (S°) to H2 S. The best studied from a biochemical perspective are the archaeon, Pyrococcus furiosus , and the bacterium, Thermotoga maritima , both of which are saccharolytic. P. furiosus is thought to contain a new type of Entner-Doudoroff pathway for the conversion of carbohydrates ultimately to acetate, H2 and CO2 . The pathway is independent of nicotinamide nucleotides and involves novel types of ferredoxin-linked oxidoreductases, one of which has tungsten, a rarely used element, as a prosthetic group. The only site of energy conservation is at the level of acetyl CoA, which in the presence of ADP and phosphate is converted to acetate and ATP in a single step. In contrast, T. maritima utilizes a conventional Embden-Meyerhof pathway for sugar oxidation. P. furiosus also utilizes peptides as a sole carbon and energy source. Amino acid oxidation is thought to involve glutamate dehydrogenase together with at least three types of novel ferredoxin-linked oxidoreductases which catalyze the oxidation of 2-ketoglutarate, aryl pyruvates and formaldehyde. One of these enzymes also utilizes tungsten. In P. furiosus , virtually all of the reductant that is generated during the catabolism of both carbohydrates and peptides is channeled to a cytoplasmic hydrogenase. This enzyme is now termed sulhydrogenase, as it reduces both protons to H2 and S°(or polysulfide) to H2 S. S° reduction appears to lead to the conservation of energy in P. furiosus but not in T. maritima , although the mechanism by which this occurs is not known. 相似文献
19.
When illuminated leaf discs and detached leaves of spinach ( Spinacia oleracea L. cv. Estivato) were exposed to 0.4 and 0.25 μl 1-1 H2 S, respectively, pool sizes of cysteine and glutathione increased. In the dark, apart from these compounds, the level of γ-glutamyl-cysteine also increased. Incubation of leaf discs with 1.0 m M buthionine sulfoximine (BSO) resulted in the accumulation of cysteine only, both in the light and in darkness. When glycine was supplied to the petioles of detached leaves exposed to H2 S in the dark, the accumulation of glutathione was stimulated, while γ-glutamyl-cysteine accumulation was prevented completely. Glycolate and glyoxylate, precursors of glycine in the glycolate pathway, had nearly the same effect as glycine. Although other amino acids were apparently taken up equally well as glycine when supplied to the petiole, they were much less effective, or not effective at all, in restoring glutathione synthesis in the dark. These results provide evidence, that H2 S-induced glutathione accumulation in spinach leaves in the dark is limited by the availability of glycine, giving rise to the accumulation of the metabolic precursor γ-glutamyl-cysteine. 相似文献
20.
Biological oxidation of hydrogen in soils flushed with a mixture of H2 , CO2 , O2 and N2 总被引:1,自引:0,他引:1
Lucia Dugnani Isabelle Wyrsch Mauro Gandolla Michel Aragno 《FEMS microbiology letters》1986,38(6):347-351
Abstract A stainless steel cylinder filled with soil was flushed upstream with a H2 /CO2 /air mixture. The consequence was a strong enrichment of the aerobic, autotrophic hydrogen-oxidising microflora, which reached densities enabling them to oxidize 84.5 ml H2 · dm−2 · h−1 in the first 25-cm layer. H2 concentration profiles, hydrogen uptake activity and cell numbers correlated well with each other. Most of the organisms isolated were dinitrogen fixers. Thus, soils containing hydrogen-oxidising bacteria may act as a biological shield between H2 -rich environments and air, and may be utilized as biofilters, e.g., in the waste-processing industry. 相似文献