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PubMed1991

Methylated sulfur compounds in microbial mats: in situ concentrations and metabolism by a colorless sulfur bacterium.

The concentrations of the volatile organic sulfur compounds methanethiol, dimethyl disulfide, and dimethyl sulfide (DMS) and the viable population capable of DMS utilization in laminated microbial ecosystems were evaluated. Significant levels of DMS and dimethyl disulfide (maximum concentrations of 220 and 24 nmol cm3 of sediment-1, respectively) could be detected only at the top 20 mm of the microbial mat, whereas methanethiol was found only at depth horizons from 20 to 50 mm (maximum concentration of 42 nmol cm3 of sediment-1). DMS concentrations in the surface layer doubled after cold hydrolysis of its precursor, dimethylsulfoniopropionate. Most-probable-number counts revealed 2.2 x 10(5) cells cm3 of sediment-1, in the 0- to 5-mm depth horizon, capable of growth on DMS as the sole source of energy. An obligately chemolithoautotrophic bacillus designated strain T5 was isolated from the top layer of the marine sediment. Continuous culture studies in which DMS was the growth-limiting substrate revealed a maximum specific growth rate of 0.10 h-1 and a saturation constant of 90 mumol liter-1 for aerobic growth on this substrate.

Disulfides↗
PubMed1991

Evolution of Volatile Sulfur Compounds during Laboratory-Scale Incubations and Indoor Preparation of Compost Used as a Substrate in Mushroom Cultivation.

Volatile sulfur compounds are known to be produced during the preparation of compost used as a substrate in mushroom cultivation. Because they cause odor problems, attempts have been made to reduce the production of these compounds. The influences of temperature and various additions on the production of volatile sulfur compounds from composting material were tested on laboratory-scale preparations. The production of H(2)S, COS, CH(3)SH, and (CH(3))(2)S was proven to be a biological process with an optimal temperature that coincides with the optimal temperature for biological activity. The formation of CS(2) and (CH(3))(2)S(2) was shown to be a nonbiological process. The emission of volatile sulfur compounds during the indoor preparation of mushroom compost appeared to be remarkably reduced (about 90%) as compared with the emission during the conventional outdoor process. Introduction of this indoor composting process would result in a significant reduction in environmental pollution.

Journal Article↗
PubMed1999

Simultaneous measurement of volatile sulfur compounds using ascorbic acid for oxidant removal and gas chromatography-flame photometric detection.

A method for the simultaneous measurement of volatile sulfur compounds (COS, H2S, CS2, CH3SH, DMS) is established with preconcentration and GC-flame photometric detection (FPD). Prior to preconcentration of ambient air, it was necessary to remove SO2, water vapor and atmospheric oxidant. SO2 and water vapor were removed using a glass fiber filter and a cooled PTFE water trap loop, respectively. In order to remove atmospheric oxidant, the efficiency of an ascorbic acid scrubber was examined. It was found that an ascorbic acid scrubber enabled measurement of volatile sulfur compounds without adsorption and reaction loss. The detection limits for COS, H2S, CS2, CH3SH and DMS were 20, 34, 35, 263 and 44 pg of S, respectively.

Air↗
PubMed2004

Differential protein expression during growth of Acidithiobacillus ferrooxidans on ferrous iron, sulfur compounds, or metal sulfides.

A set of proteins that changed their levels of synthesis during growth of Acidithiobacillus ferrooxidans ATCC 19859 on metal sulfides, thiosulfate, elemental sulfur, and ferrous iron was characterized by using two-dimensional polyacrylamide gel electrophoresis. N-terminal amino acid sequencing and mass spectrometry analysis of these proteins allowed their identification and the localization of the corresponding genes in the available genomic sequence of A. ferrooxidans ATCC 23270. The genomic context around several of these genes suggests their involvement in the energetic metabolism of A. ferrooxidans. Two groups of proteins could be distinguished. The first consisted of proteins highly upregulated by growth on sulfur compounds (and downregulated by growth on ferrous iron): a 44-kDa outer membrane protein, an exported 21-kDa putative thiosulfate sulfur transferase protein, a 33-kDa putative thiosulfate/sulfate binding protein, a 45-kDa putative capsule polysaccharide export protein, and a putative 16-kDa protein of unknown function. The second group of proteins comprised those downregulated by growth on sulfur (and upregulated by growth on ferrous iron): rusticyanin, a cytochrome c(552), a putative phosphate binding protein (PstS), the small and large subunits of ribulose biphosphate carboxylase, and a 30-kDa putative CbbQ protein, among others. The results suggest in general a separation of the iron and sulfur utilization pathways. Rusticyanin, in addition to being highly expressed on ferrous iron, was also newly synthesized, as determined by metabolic labeling, although at lower levels, during growth on sulfur compounds and iron-free metal sulfides. During growth on metal sulfides containing iron, such as pyrite and chalcopyrite, both proteins upregulated on ferrous iron and those upregulated on sulfur compounds were synthesized, indicating that the two energy-generating pathways are induced simultaneously depending on the kind and concentration of oxidizable substrates available.

Acidithiobacillus↗
PubMed1975

Replacing dietary methionine and cystine in chick diets with sulfate or other sulfur compounds.

A purified diet deficient in the sulfur amino acids and sulfate was fed to chicks in tests designed to compare the effectiveness of several sulfur compounds in sparing the sulfur amino acids. The addition of a mixture of methionine and cystine to this diet increased growth rate and feed efficiency more than any of the other additions. Sulfate improved performance as much as any inorganic sulfur source tested. Taurine, sulfite, thiosulfate, and sulfur also had value. When graded levels of sulfate were added to diets with sulfur amino acid levels about 0.2 and 0.3% below the level required for optimum performance, the weight gain and feed efficiency response curves were curvilinear. Most of the response to sulfate was produced with a level of 200 p.p.m., but 500 to 660 p.p.m. was needed to produce the maximum sparing effect. The sulfur amino acid requirement was found to be about 0.075% less with 0.1% sulfate in the diet than without it when growth rate was the criterion. When feed efficiency was the criterion, the requirement was reduced about 0.05% by sulfate.

Animals↗
PubMed2005

Involvement of a branched-chain aminotransferase in production of volatile sulfur compounds in Yarrowia lipolytica.

The enzymatic degradation of L-methionine and the subsequent formation of volatile sulfur compounds (VSCs) are essential for the development of the typical flavor in cheese. In the yeast Yarrowia lipolytica, the degradation of L-methionine was accompanied by the formation of the transamination product 4-methylthio-2-oxobutyric acid. A branched-chain aminotransferase gene (YlBCA1) of Y. lipolytica was amplified, and the L-methionine-degrading activity and the aminotransferase activity were measured in a genetically modified strain and compared to those of the parental strain. Our work shows that L-methionine degradation via transamination is involved in formation of VSCs in Y. lipolytica.

Amino Acid Sequence↗
PubMed2003

Breath-odor evaluation by detection of volatile sulfur compounds--correlation with organoleptic odor ratings.

Volatile sulfur compounds are known to be major contributors to oral malodor, and their detection by gas chromatography (GC) is a commonly used method for evaluating breath odor in clinical trials. A custom-designed breath-sampling GC system was developed for this purpose. A clinical study was performed to compare the performance of this instrumental method to organoleptic evaluation by trained odor judges. A statistically significant correlation was found between the measured levels of volatile sulfurs and the ratings of the odor judges. Both methods performed similarly in evaluating the breath-freshening effects of two test products. These results demonstrate the strength of the GC method for evaluating breath odor and predicting the breath-freshening effects of oral-care products.

Adult↗
PubMed2001

Kinetics of oxidation of odorous sulfur compounds in aqueous alkaline solution with H2O2.

Sulfur species oxidation is a crucial issue wastewater treatment. The production of sulfur compounds like H2S,CH3SH, C2H5SH, disulfides and dimethyle sulfide generates odorous nuisances for the neighborhood. The oxidation of these species by H2O2 in alkaline solution has been investigated. The results showed that thiols CH3SH and C2H5SH react with H202 only in their dissociated form RS- with rate constants respectively k = 8.81 +/- 0.48 M-1s-1 and 8.37 +/- 0.63 M-1.s-1. Mercaptans oxidation produces 100 % of dimethyldisulfide or diethyldisulfide. The oxidation of disulfides shows a difference of reactivity between H2O2 and HO2- towards sulfur species. Increasing the pH accelerates significantly the reactions in the case of CH3SSCH3. The oxidation rate can be described as: r = k[RSSR][H2O2][RSSR][H2O2] + k[RSSR][HO2-] [RSSR][HO2-] with k[RSSR][H2O2] = 1.2 x 10(-4) +/- 0.2 x 10(-4) M-1s-1 and k[RSSR][HO2-] = 3.4 x 10(-4) +/- 0.6 x 10(-4) M-1.s-1 for CH3SSCH3. Dimethyl sulfide presents a reactivity different from disulfides. The oxidation rate can also be described as: r = k[CH3SCH3][H2O21][CH3SCH3][H2O2] + k[CH3SCH3][HO-] [CH3SCH3][HO2-], however, oxidation rate decreases with pH increase. k[CH3SCH3][H2O2] = 12.8 x 10(-3) +/- 0.96 x 10(-3) M-1.s-1 and k[CH3SCH3][HO2-] = 4 x 10(-3) +/- 0.3 x 10(-3) M-1.s-1.

Hydrogen Peroxide↗
PubMed2004

Ionizing radiation and antioxidants affect volatile sulfur compounds, lipid oxidation, and color of ready-to-eat Turkey bologna.

Bologna was processed from ground turkey breast meats containing one of four antioxidant treatments (none, rosemary extract, sodium erythorbate, and sodium nitrite). After it was cooked, the bologna was sliced, sealed in gas impermeable bags, exposed to 0, 1.5, and 3.0 kGy gamma-radiation, and then stored at 5 degrees C for up to 8 weeks. Thiobarbuturic acid reactive substances (TBARS), color, and volatile sulfur compounds were measured every 2 weeks during storage. Irradiation had no consistent effect on TBARS values. The rosemary extract and sodium nitrite inhibited, while erythorbate increased, TBARS values, independent of radiation dose or storage time. Irradiation promoted redness and reduced yellowness of the control (no antioxidant) bologna at weeks 0 and 2. The use of nitrite and rosemary extract inhibited the changes in color due to irradiation. Several volatile sulfur compounds (hydrogen sulfide, methanethiol, methyl sulfide, and dimethyl disulfide), measured using a pulsed flame photometric detector, increased with radiation dose. However, none of the antioxidants had any substantial effect on volatile sulfur compounds induced by irradiation. Our results suggest that antioxidants did not consistently affect irradiation-induced volatile sulfur compounds of turkey bologna although they did significantly impact color and lipid oxidation.

Animals↗
PubMed2006

Volatile organic sulfur compounds in a stratified lake.

Three volatile organic sulfur compounds (VOSCs), dimethyl sulfide (DMS), carbon disulfide (CS(2)), and dimethyl disulfide (DMDS), were detected in the stratified water column of a lake (Linsley Pond) in Connecticut. The compounds DMS and DMDS appeared in both the oxic and the anoxic portions of the water column, CS(2) was primarily found in anoxic hypolimnion. Algal metabolism and/or bacterial degradation of sulfur-containing amino acids or other organic materials are potential sources of VOSCs in the oxic lake water. Reactions of hydrogen sulfide with organic compounds and microbial degradation of organic matter may be responsible for the production of VOSCs in the anoxic lake water. The vertical distribution patterns of these three VOSCs varied from month to month in the summer, but the daily profiles obtained in one 5-day period in the summer displayed consistency. No clear diurnal pattern for any of the three VOSCs was observed. Based on observation that these VOSCs were not present in surface and near surface waters of Linsley Pond, freshwater inputs of reduced sulfur compounds to the atmosphere may be insignificant.

Carbon Disulfide↗
PubMed1998

Abatement of volatile organic sulfur compounds in odorous emissions from the bio-industry.

Compounds of interest in this work are methanethiol (MeSH), dimethyl sulfide (Me2S), dimethyl polysulfides (Me2Sx) and carbon disulfide (CS2) since these volatiles have been identified as predominant odorants in the emission of a wide range of activities in the bio-industry (e.g. aerobic waste water treatment plants, composting plants, rendering plants). In these processes, the occurrence of volatile organic sulfur compounds is mainly related to the presence of anaerobic microsites with consecutive fermentation of sulfur containing organic material and/or to the breakdown of the latter due to thermal heating. Due to the chemical complexity of these low-concentrated waste gas streams and the high flow rates to be handled, mainly biotechnological techniques and scrubbers can be used to control the odour emission. When using biofilters or trickling filters, inoculation with specific microorganisms and pH-control strategies should be implemented to optimise the removal of volatile organic sulfur compounds. In scrubbers, chemical oxidation of the volatile organic sulfur compounds can be obtained by dosing hypochlorite, ozone or hydrogen peroxide to the scrubbing liquid. However, optimal operational conditions for each of these abatement techniques requires a further research in order to guarantee a long-term and efficient overall odour abatement.

Anaerobiosis↗
PubMed1989

The capacity of subgingival microbiotas to produce volatile sulfur compounds in human serum.

Hydrogen sulfide is formed by the subgingival microbiotas of periodontal pockets. The capacity of these microbiotas to form various volatile sulfur compounds in human serum was studied. Bacterial samples from nine deep periodontal pockets were incubated for 7 days in human serum and the amounts of volatile sulfur compounds and the degradation of serum proteins were determined. Hydrogen sulfide was the predominant volatile sulfur compound, but also methyl mercaptan was formed in significant amounts. Only traces of dimethyl sulfide and dimethyl disulfide were detected. There was an extensive degradation of the serum proteins. In most of the reaction mixtures hydrogen sulfide reached highly toxic levels.

Bacteria↗
PubMed1993

Reducing sulfur compounds of the colon impair colonocyte nutrition: implications for ulcerative colitis.

BACKGROUND: Mercaptides (sodium hydrogen sulfide and sodium methanethiol) and mercapto-fatty acid (sodium mercaptoacetate) are reducing agents that help to maintain anaerobic conditions in the colonic lumen. The metabolic effect of these agents on n-butyrate and glucose oxidation in human colonocytes is unknown. METHODS: Isolated human colonocytes were prepared from 31 colectomy specimens, and generation of oxidative metabolites from [1-14C]n-butyrate and [6-14C]glucose was measured in the presence and absence of reducing agents. Injury to cells was judged by diminished production of metabolites. RESULTS: The injurious action of mercaptides at all sites of the colon was of the order of sodium hydrogen sulfide > methanethiol > mercaptoacetate. Significant inhibition of n-butyrate (< 0.005) but not glucose oxidation was observed with sodium hydrogen sulfide in the ascending colon, splenic flexure, and rectosigmoid region. Hydrogen sulfide more significantly inhibited fatty acid oxidation in the rectosigmoid than in the ascending colon (P < 0.02). CONCLUSIONS: Metabolic effects of sodium hydrogen sulfide on butyrate oxidation along the length of the colon closely mirror metabolic abnormalities observed in active ulcerative colitis, and the increased production of sulfide in ulcerative colitis suggests that the action of mercaptides may be involved in the genesis of ulcerative colitis.

Colitis, Ulcerative↗
PubMed1962

Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactilyticus. II. Stoichiometry with inorganic sulfur compounds.

Woolfolk, C. A. (University of Washington, Seattle). Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactilyticus. II. Stoichiometry with inorganic sulfur compounds. J. Bacteriol. 84:659-668. 1962.-Extracts of Micrococcus lactilyticus (Veillonella alcalescens) are capable of utilizing molecular hydrogen for the reduction of metabisulfite (pyrosulfite) to thiosulfate via dithionite as an intermediate. The first step of metabisulfite reduction (i.e., to dithionite) is reversible, and, when dithionite is added as a substrate, there is an evolution of molecular hydrogen accompanied by the formation of equilibrium concentrations of metabisulfite. Kinetic studies indicate that dithionite may be directly reduced to thiosulfate without the formation of sulfoxylate as an intermediate. Although tetrathionate is reduced to thiosulfate with an uptake of hydrogen, polythionates probably are not formed as intermediates in the reduction of metabisulfite to thiosulfate.

Hydrogen↗