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PubMed2001

Effect of various dairy packaging materials on the headspace analysis of ultrapasteurized milk.

Milk from three different dairies (each a separate trial: 1, 2, and 3) was standardized to 2% fat and processed at 140.6, 129.4, 118.3, and 107.2 degrees C (temperatures 1, 2, 3, and 4, respectively) for 2 s and packaged into six different packaging boards [standard (A) milk boards with standard seam, juice boards with standard (B) and J- bottom (D) seams, barrier boards with standard (C) and J-bottom (E) seams, and foil (F) boards with J-bottom seam] resulting in 24 different treatments. A Shimadzu 15A series chromatograph equipped with a Porapak-P column was used to measure the headspace of the milk stored at 6.7 degrees C for 1, 2, 3, 5, 10, and 15 wk of storage. Gas chromatographic headspace analysis for sulfur compounds showed that hydrogen sulfide, methanethiol, and dimethyl sulfide were detected in milk processed at 140.6, 129.4, 118.3, and 107.2 degrees C. In addition, dimethyl disulfide was detected in milk processed at 140.6 and 129.4 degrees C, and dimethyl trisulfide was detected at 140.6 degrees C. Milk processed at 140.6 degrees C contained the most sulfur compounds. Samples C1, E1, and F1 retained the most hydrogen sulfide and methanethiol at 6 d of storage. Methanethiol appeared to be heat-induced. At wk 6, a slightly hammy or cardboardy flavor was detected for milk packaged in boards with standard seams (A, B, and C), and a slightly cooked flavor was detected for milk packaged in barrier and foil boards with J-bottom (E and F) seams. The hammy or cardboardy flavor intensified with storage time, and all of the cooked flavor dissipated at wk 10.

Animals↗
PubMed2001

Organically bound sulfur in refractory organic substances.

The sulfur compounds of refractory organic substances (ROS) of different origin have been characterized. Total organic sulfur was determined by elemental analysis. Sulfur-containing amino acids methionine and cystine were analyzed chromatographically after hydrolysis with HCl or by proteolytic digestion using enzymes. The results obtained from elemental analysis show that the total amount of sulfur is strongly dependent on the origin of the samples, because of different environmental factors during the formation of ROS. For naturally occurring samples isolated from soil seepage water, bog lake water and ground water the carbon-to-sulfur atomic ratios (C/S) decrease with the stage of humification, because of preferential loss of carbon. In humic acids (HA) isolated from secondary effluent the high value of the nitrogen-to-sulfur ratio (N/S) was indicative of a large amount of protein-derived nitrogen and sulfur compounds. In the solutions from acid hydrolysis the total amount of amino acid carbon related to the dissolved organic carbon (DOC) was generally less than 5%. Percentages of cystine related to all the amino acids detected were in the range 4 to 16%; methionine was below the detection limit for most samples. The results show that cystine is very important among the amino acids released. Enzymatic release generally resulted in smaller amounts of amino acids, indicating that these molecules are not only present in bioavailable protein-like structures. The data were compared with those from other approaches reported in the literature for the speciation of sulfur forms in ROS, including potentiometric titration, differential reduction methods, and spectroscopic investigations.

Amino Acids, Sulfur↗
PubMed2000

A new facultatively autotrophic hydrogen- and sulfur-oxidizing bacterium from an alkaline environment.

An alkaliphilic bacterium, strain AHO 1, was isolated from an enrichment culture with hydrogen at pH 10 inoculated with a composite sample of sediments from five highly alkaline soda lakes (Kenya). This bacterium is a gram-negative, nonmotile, rod-shaped, obligately aerobic, and facultatively autotrophic hydrogen-oxidizing organism. It was able to oxidize reduced sulfur compounds to sulfate during heterotrophic growth. It utilized a wide range of organic compounds as carbon and energy sources and grew mixotrophically with hydrogen and acetate. With sulfur compounds, mixotrophic growth was observed only in acetate-limited continuous culture. The normal pH range for autotrophic growth with hydrogen was pH 8.0-10.25, with a pH optimum at 9-9.5. Growth at pH values lower than 8.0 was extremely slow. Heterotrophic growth with acetate was optimal at pH 10.0. The hydrogen-oxidizing activity of whole cells was maximal at pH 9.0 and still substantial up to pH 11. NAD-dependent hydrogenase activity was found in the soluble fraction of the cell-free extract, but no methylene blue-dependent activity in either the soluble or membrane fractions was observed. On the basis of its pH profile, the soluble hydrogenase of strain AHO 1 was a typical pH-neutral enzyme. Phylogenetic analysis revealed that strain AHO 1 belongs to the alpha-3 subgroup of the Proteobacteria with a closest relation to a recently described alkaliphilic aerobic bacteriochlorophyll a-containing bacterium "Roseinatronobacter thiooxidans."

Alkalies↗
PubMed2002

The gamma-glutamyltransferase activity and non-protein sulfhydryl compounds levels in rat kidney of different age groups.

The present work was aimed to obtain information about age-dependent changes of gamma-glutamyltransferase (GGT) activity and the levels of non-protein sulfhydryl compounds (NPSH) in rat kidneys. In addition, protein-bound cysteine (PB-Cys), sulfane sulfur compounds and reactive oxygen species (ROS) were estimated. The results indicate that the activity of GGT and NPSH levels in the kidneys are reduced with age. At the same time, a significant increase in the level of protein-bound cysteine was observed. Simultaneously, the content of sulfane sulfur compounds was increased in the group of the oldest animals. These findings indicate that the capacity for extracellular glutathione degradation and, in consequence, the availability of cysteine for intracellular glutathione biosynthesis may be impaired. The increased PB-Cys level indicates potentiation of the thiolation reaction, i.e. development of protein-mixed disulfides. These results reveal age dependent disturbances in the thiol-disulfide equilibrium in the kidneys which leads to an imbalance between pro- and antioxidatory processes.

Aging↗
PubMed1999

Effect of noble metal conditioners on bonding between prosthetic composite material and silver-palladium-copper-gold alloy.

STATEMENT OF PROBLEM: Mechanical retentive devices and the application of complicated surface preparation have been indispensable for bonding composite material to the metal substructure of restorations. PURPOSE: This study evaluated the priming effects of 4 metal conditioners on bonding between a prosthetic veneering material and a silver-palladium-based casting alloy. MATERIAL AND METHODS: Four primers designed for conditioning noble metal alloys (Alloy Primer, Metaltite, Metal Primer II, and V-Primer) were assessed (all materials contain organic sulfur compounds). Cast disk specimens made of silver-palladium-copper-gold alloy (Castwell M.C.12) were primed with 1 of the 4 primers, and bonded with a light-activated prosthetic composite material (Axis). Shear testing was performed before and after thermocycling for evaluation of bond durability. RESULTS: All primed groups showed improved 24-hour bond strengths compared with the unprimed group. After thermocycling, 3 groups primed with the Metal Primer II, Alloy Primer, and Metaltite agents exhibited the highest bond strength. CONCLUSION: Use of 1-liquid metal conditioners containing sulfur compounds was a simple and useful method for improving bonding between the alloy and the composite material tested.

Composite Resins↗
PubMed2002

Identification of a thiosulfate utilization gene cluster from the green phototrophic bacterium Chlorobium limicola.

Chlorobium is an autotrophic, green phototrophic bacterium which uses reduced sulfur compounds to fix carbon dioxide in the light. The pathways for the oxidation of sulfide, sulfur, and thiosulfate have not been characterized with certainty for any species of bacteria. However, soluble cytochrome c-551 and flavocytochrome c (FCSD) have previously been implicated in the oxidation of thiosulfate and sulfide on the basis of enzyme assays in Chlorobium. We have now made a number of observations relating to the oxidation of reduced sulfur compounds. (1) Western analysis shows that soluble cytochrome c-551 in Chlorobium limicola is regulated by thiosulfate, consistent with a role in the utilization of thiosulfate. (2) A membrane-bound flavocytochrome c-sulfide dehydrogenase (which is normally a soluble protein in other species) is constitutive and not regulated by sulfide as expected for an obligately autotrophic species dependent upon sulfide. (3) We have cloned the cytochrome c-551 gene from C. limicola and have found seven other genes, which are also presumably involved in sulfur metabolism and located near that for cytochrome c-551 (SoxA). These include genes for a flavocytochrome c flavoprotein homologue (SoxF2), a nucleotidase homologue (SoxB), four small proteins (including SoxX, SoxY, and SoxZ), and a thiol-disulfide interchange protein homologue (SoxW). (4) We have established that the constitutively expressed FCSD genes (soxEF1) are located elsewhere in the genome. (5) Through a database search, we have found that the eight thiosulfate utilization genes are clustered in the same order in the Chlorobium tepidum genome (www.tigr.org). Similar thiosulfate utilization gene clusters occur in at least six other bacterial species but may additionally include genes for rhodanese and sulfite dehydrogenase.

Amino Acid Sequence↗
PubMed2004

Tongue-cleaning methods: a comparative clinical trial employing a toothbrush and a tongue scraper.

BACKGROUND: It is estimated that approximately 85% of all halitosis cases have their origin within the mouth; of these, 50% are caused by tongue residues. Previous studies have established that hydrogen sulfide and mercaptans are the primary components of halitosis. Thus, tongue cleaning gains importance as a means of halitosis management. METHODS: This investigation compared the efficacy of two mechanical methods for tongue cleaning through a handheld sulfide monitor. This crossover trial was carried out with 10 healthy subjects, 20 to 50 years old. Before the baseline measurement of the volatile sulfur compounds (VSCs), the subjects were instructed to refrain from any tongue cleaning method for 48 hours. The 10 participants were then placed in one of two groups (five each): 1) first week: tongue scraper, second week: soft-bristle toothbrush; 2) first week: toothbrush, second week: tongue scraper, with a 48-hour wash-out period between each week. RESULTS: The baseline measurements were compared with those of the end of each week using the Dunn method (alpha = 0.01). The tongue scraper showed a 75% reduction in VSCs, while the toothbrush only achieved a 45% reduction in VSCs. CONCLUSION: Although the tongue coating was removed by both methods, the tongue scraper performed better in reducing the production of volatile sulfur compounds.

Adult↗
PubMed2004

Dynamics of sulfur amino acids in mammalian brain: assessment of the astrocytic-neuronal cysteine interaction by a mathematical hybrid model.

A mathematically hybrid model was used to analyze three mechanisms by which cysteine could be produced in the brain to be used as preferential substrate in the synthesis of neuronal glutathione. In that way, the fluxes of sulfur-compounds at the brain-blood barrier were integrated with their transport in astrocytes and neurons, and with their metabolism in astrocytes. We concluded that cysteine, in contrast with its precursor cystine, would not be taken up from the blood at the blood-brain barrier, but instead it must be lost continuously from astrocytes. Cysteine efflux is produced because the uptake of cystine in astrocytes is much greater than their cysteine demand to synthesize glutathione, hypotaurine and taurine. Once in the interstitial parenchyma, cysteine would be taken for the neurons, as backwardly by the endothelial cells. Remarkably, a close sulfur-macro balance can be maintained only if the surplus of the produced cysteine is transferred from the endothelial cells to the blood together with significant amounts of other sulfur-compounds, probably taurine and hypotaurine. In addition, the results obtained shown that alternative mechanisms of cysteine generation (i.e., nonenzymatic-thiol-disulfide exchange reaction, enzymatic cleavage of the glutathione effluxed from astrocytes) are not quantitatively significant under physiological conditions, in situ.

Animals↗
PubMed2004

High incidence of suicide by burning in Masjid-i-Sulaiman (southwest of Iran), a polluted area with natural sour gas leakage.

Masjid-i-Sulaiman (MIS) is located in the southwest of Iran. Unfortunately, some parts of MIS are contaminated by subsurface leakage of natural gas containing H(2)S. In order to investigate the possible effect(s) of chronic exposure to sulfur compounds on suicidal behavior, the present study was done. In the 2-year period, 561 individuals attempted suicide (260 men and 301 women). Completed suicide comprised of 19 men and 32 women. The rate per 100,000 person-years was 19.9 for men and 34.8 for women aged over 15 years. Forty-two (13 men and 29 women) of 561 patients were self-immolators by fire with a male:female ratio 0.45. This represents 22.4 burns per 100,000 person-years and is equivalent to 7.4% of all suicide attempts. Thirty-three of 42 patients died (78.6%) who were 9 men and 24 women with male:female ratio 0.37. There is statistically significant differences between sex groups (P((2)) = 0.0091). The self-inflicted burn was the most frequent method for lethal suicide. Winter was the most common season for self-burning followed by spring. Statistical analysis showed significant difference between seasons for self-inflicted burn (P((2)) = 0.00001). Analysis of correlation showed statistically positive correlation coefficient between mean values of all reactive sulfur compounds and seasonal frequency of suicide (r = 0.923, P((1)) = 0.038).

Adult↗
PubMedDate not supplied

[Two new species of microaerophilic sulfur spirilla, Spirillum winogradskii sp. nov. and Spirillum kriegii sp. nov].

New microaerophilic sulfur-oxidizing spirilla were isolated from hydrogen sulfide sludge of wastewater treatment plants. Strains D-427 and D-430 have spiral cells that are highly motile due to bipolar flagellum bundles covered with mucous sheaths. Under a phase-contrast microscope, these bundles are visible as single polar flagella. Spheroplasts are formed in the stationary growth phase. Both strains are obligate organotrophs able to oxidize a number of reduced sulfur compounds. The oxidation of sulfide and polysulfide leads to the formation of intracellular globules of elemental sulfur; thiosulfate oxidation results in tetrathionate accumulation in the medium. The cells are unable to utilize reduced sulfur compounds in the energy metabolism; their oxidation is caused by a chemical interaction with H2O2 and O2, synthesized in the electron transport chain. Both strains are obligate microaerophiles with an optimal oxygen concentration in the gas phase of 2 and 0.8% for strains D-427 and D-430, respectively. The strains utilize a limited number of organic acids as growth substrates, mainly tricarboxylic-acid-cycle intermediates. The DNA G+C content is 38.0 mol % (T(m)) for strain D-427 and 38.9 mol % for strain D-430. Phylogenetic analysis, based on the comparison of 16S rRNA gene sequences, revealed that the new isolates of sulfur spirilla are the most closely related to Spirillum volutans, the type species of the genus (97.4% similarity). They were assigned to the genus Spirillum within the class Beta-proteobacteria as two new species, S. winogradskii sp. nov. (D-427T = DSM 12756T) and S. kriegii sp. nov. (B-430T = BKM B-2372T). The emended description of the genus Spirillum is provided.

Genotype↗
PubMed2001

Volatile constituents of Chinese chive (Allium tuberosum Rottl. ex Sprengel) and rakkyo (Allium chinense G. Don).

Volatile components were isolated from Chinese chive and rakkyo by simultaneous steam distillation-solvent extraction and analyzed by GC and GC-MS. Sulfur compounds account for 88 and 94% of the total volatiles in the isolated extract of Chinese chive and rakkyo, respectively. In addition to the sulfur compounds commonly reported in the genus Allium, 27 novel volatile sulfur-containing components were found in the isolated extracts of both species. Among them were a sulfide, disulfides, trisulfides, and tetrasulfides with ethyl, butyl, and pentyl groups.

Allium↗
PubMed1998

Biocatalytic sulfur removal from fuels: applicability for producing low sulfur gasoline.

Environmental regulations are driving R&D efforts to produce low sulfur fuels, including diesel fuel and gasoline for motor vehicles. Biocatalytic sulfur removal from fuels has potential applicability for producing low sulfur gasoline. Microbial biocatalysts have been identified that can biotransform sulfur compounds found in fuels, including ones that selectively remove sulfur from dibenzothiophene heterocyclic compounds. Most attention is give to the 4S pathway of Rhodococcus, which can remove sulfur from substituted and unsubstituted dibenzothiophenes, including sulfur compounds that hinder chemical catalysis and that resist removal by mild hydrotreatment. Various bioreactor and bioprocess designs are being tested for use with biocatalysts, including recombinant biocatalysts, for use in removing sulfur from fuels and feedstocks within the petroleum refinery stream. With bioprocess improvements that enhance biocatalyst stability, achieve faster kinetics, improve mass transfer limitations, temperature and solvent tolerance, as well as broaden substrate specificity to attack a greater range of heterocyclic compounds, biocatalysis may be a cost-effective approach to achieve the production of low sulfur gasoline. The challenge will be to accomplish these improvements by the time the regulations for low sulfur gasoline and other vehicle fuels go into effect in order to be competitive with emerging nonbiological desulfurization technologies.

Fossil Fuels↗
PubMed1993

Evaluation of the contribution of chronic skin irritation and selected compositional parameters to the tumorigenicity of petroleum middle distillates in mouse skin.

Two-year skin carcinogenicity studies were conducted in C3H mice to assess the effects of irritation and selected compositional parameters on the carcinogenic potential of four petroleum liquids. Three samples (lightly refined paraffinic oil, LRPO; lightly hydrodesulfurized specialty oil, LHSO; jet fuel, JF) can be generically classified as middle distillates, i.e. distillation occurs between 350 and 700 degrees F (175-370 degrees C). The fourth sample was a Steam Cracked Gas Oil (SCGO) that distilled within the same range. In studies that assess the effects of irritation on tumorigenicity, LRPO was tested undiluted or was diluted to 50% and 25% in either mineral oil (which eliminated irritation of the skin) or toluene (which did not). Undiluted LRPO elicited tumors in 8% of the mice. Both dilution procedures eliminated tumorigenic potential. Thus, it was possible to maintain a visible level of skin irritation equivalent to that elicited by undiluted LRPO without inducing tumors. SCGO elicited a chronic irritant state grossly equivalent to LRPO but was not tumorigenic. Jet Fuel A (JF) was tested undiluted using both a standard skin painting protocol and an intermittent dosing schedule in which treatment was suspended periodically to allow skin irritation to resolve. The standard treatment protocol of JF resulted in both marked skin irritation and tumors in 44% of the mice. However, using the intermittent schedule, the tumor yield was reduced to 2%. Collectively these data demonstrate that tumor formation is not a necessary sequelae to chronic skin irritation. Conversely, prevention of a marked chronic irritant state was accompanied by decreased tumor yield. These data suggest that the chronic irritant state may be a necessary but not sufficient condition for tumor formation. In studies to assess the effects of compositional parameters, a lightly hydrodesulfurized specialty oil (LHSO) similar to LRPO but refined to have negligible levels of sulfur compounds (3 ppm), elicited chronic irritant and tumor responses (10%) similar to LRPO. Thus, the level of sulfur compounds does not appear to affect the tumorigenic activity for products in this boiling range. The SCGO which did not produce tumors contained only aromatic hydrocarbons, a finding consistent with previous reports that aromatics may not be the source of tumorigenic potential in petroleum fractions boiling between 350 and 700 degrees F (175-370 degrees C).

Animals↗
PubMed1972

Bacteriogenic sulfur in air pollution.

On a yearly basis, the major source of atmospheric sulfur compounds in and near Salt Lake City, Utah, is industrial. Isotopic studies suggest that the next most important source is bacteriogenic sulfur released by anaerobes from muds. On a seasonal basis, the bacteriogenic source of sulfur compounds may rival the industrial source in importance.

Air Pollution↗
PubMed2006

Cancer chemoprevention by garlic and garlic-containing sulfur and selenium compounds.

As early as 1550 B.C., Egyptians realized the benefits of garlic as a remedy for a variety of diseases. Many epidemiological studies support the protective role of garlic and related allium foods against the development of certain human cancers. Natural garlic and garlic cultivated with selenium fertilization have been shown in laboratory animals to have protective roles in cancer prevention. Certain organoselenium compounds and their sulfur analogs have been identified in plants. Organoselenium compounds synthesized in our laboratory were compared with their sulfur analogs for chemopreventive efficacy. Diallyl selenide was at least 300-fold more effective than diallyl sulfide in protecting against 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary adenocarcinomas in rats. In addition, benzyl selenocyanate inhibited the development of DMBA-induced mammary adenocarcinomas and azoxymethane-induced colon cancer in rats and benzo[a]pyrene-induced forestomach tumors in mice. The sulfur analog, benzyl thiocyanate, had no effect under the same experimental conditions. Furthermore, we showed that 1,4-phenylenebis(methylene)selenocyanate, but not its sulfur analog, significantly inhibited DMBA-DNA adduct formation and suppressed DMBA-induced mammary carcinogenesis. Collectively, these results indicate that structurally distinctive organoselenium compounds are superior to their corresponding sulfur analogs in cancer chemoprevention. Additionally, synthetic aromatic selenocyanates are more effective cancer chemopreventive agents than the naturally occurring selenoamino acids. Because plants are capable of utilizing selenium in a manner similar to that in sulfur assimilation pathways, future studies should aim at determining whether, under appropriate conditions, these potent cancer chemopreventive synthetic selenium compounds can be synthesized by garlic and related allium foods.

Animals↗
PubMed2025

Genome-based exploration of volatile flavor diversity from food yeast species.

Yeast shares a longer than 10 000-year history with humans in food fermentation by producing various volatile flavor compounds that contribute to the final taste and aroma of foods. Yeast-associated volatile flavor compounds include esters, benzenoids, sulfur compounds, and phenolic derivatives, which enhance the sensory complexity of fermented foods and beverages. Genome-scale technologies have advanced and transformed our understanding of the genetic and evolutionary drivers of volatile flavor diversity. The conventional approach to aroma enrichment and flavor balancing through single-strain optimization has been redefined through yeast cofermentation strategies, such as the pairing of Saccharomyces cerevisiae with nonconventional yeast species. This minireview summarizes the latest genomic insights into volatile flavor compound formation through ester, benzenoid, sulfur, and phenolic pathways in various yeast species and highlights the shaping of the next generation of food fermentation innovation via cofermentation combined with omics analysis, followed by a future perspective on synthetic biology for industrial applicability.

Volatile Organic Compounds↗