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PubMed1997

A rapid and simple method for estimating sulfate reduction activity and quantifying inorganic sulfides.

A simplified passive extraction procedure for quantifying reduced inorganic sulfur compounds from sediments and water is presented. This method may also be used for the estimation of sulfate reduction rates. Efficient extraction of FeS, FeS(inf2), and S(sup2-) was obtained with this procedure; however, the efficiency for S(sup0) depended on the form that was tested. Passive extraction can be used with samples containing up to 20 mg of reduced sulfur. We demonstrated the utility of this technique in a determination of both sulfate reduction rates and reduced inorganic sulfur pools in marine and freshwater sediments. A side-by-side comparison of the passive extraction method with the established single-step distillation technique yielded comparable results with a fraction of the effort.

Journal Article↗
PubMed1995

Cycloclasticus pugetii gen. nov., sp. nov., an aromatic hydrocarbon-degrading bacterium from marine sediments.

Three heterotrophic bacterial strains were isolated from different locations in Puget Sound, Washington, by using biphenyl as the principal carbon source. These strains grow by using a limited number of organic compounds, including the aromatic hydrocarbons naphthalene, phenanthrene, anthracene, and toluene, as sole carbon sources. These aerobic, gram-negative rods are motile by means of single polar flagella. Their 16S rRNA sequences indicate that they are all members of the gamma subdivision of the Proteobacteria. Their closet known relatives are the genera Methylobacter and Methylomonas (genera of methane-oxidizing bacteria), uncultured sulfur-oxidizing symbionts found in marine invertebrates, and clone FL5 containing 16S ribosomal DNA amplified from an environmental source. However, the Puget Sound bacteria do not use methane or methanol as a carbon source and do not oxidize reduced sulfur compounds. Furthermore, a 16S rRNA base similarity comparison revealed that these bacteria are sufficiently different from other bacteria to justify establishment of a new genus. On the basis of the information summarized above, we describe a new genus and species, Cycloclasticus pugetti, for these bacteria; strain PS-1 is the type strain of C. pugetti.

Base Composition↗
PubMed2006

Comparison of cultivation-dependent and molecular methods for studying the diversity of anoxygenic purple phototrophs in sediments of an eutrophic brackish lagoon.

Phototrophic anoxygenic purple bacteria play a key role in many aquatic ecosystems by oxidizing sulfur compounds and low-molecular-weight organic compounds using light as energy source. In this study, molecular methods based upon pufM gene (photosynthetic unit forming gene) were compared with culture-dependent methods to investigate anoxygenic purple phototrophic communities in sediments of an eutrophic brackish lagoon. Thirteen strains, belonging to eight different genera of purple phototrophic bacteria were isolated with a large dominance of the metabolically versatile purple non-sulfur bacteria (eight strains), some purple sulfur bacteria (three strains) and two strains belonging to the Roseobacter clade (aerobic phototrophs). The pufM genes amplified from the isolated strains were not detected by the molecular methods [terminal-restriction fragment length polymorphism (T-RFLP)] applied on in situ communities. An environmental clone library of the pufM gene was thus constructed from sediment samples. The results showed that most of the clones probably corresponded to aerobic phototrophic bacteria. Our results demonstrate that the culture-dependent techniques remain the best experimental approach for determining the diversity of phototrophic purple non-sulfur bacteria whereas the molecular approach clearly illustrated the abundance of organisms related to the Roseobacter clade in these eutrophic sediments.

Bacterial Proteins↗
PubMed1983

Sodium diethyl dithiocarbamate and the mononuclear phagocytic system in guinea pigs.

Sodium diethyl dithiocarbamate (DTC) is a low molecular weight sulfur compound which has been previously shown to have immunomodulatory properties. In the present report, the effects of DTC on the mononuclear phagocytic system were studied in guinea pigs. The colloidal gold clearance was enhanced in animals which received an i.v. injection of 10 mg DTC on day -13, but not in animals treated on day -8 with DTC. DTC treatment modified neither 99mTc sulfur colloid uptake nor activation markers in peritoneal macrophage monolayers. These results show that DTC which modulates both delayed hypersensitivity and antibody synthesis only enhances nonspecific binding of macrophages but leaves unaffected endocytosis and metabolic status of macrophages.

Animals↗
PubMed2006

Sulfide removal by moderate oxygenation of anaerobic sludge environments.

Introduction of a limited amount of oxygen to anaerobic bioreactors is proposed as a simple technique to lower the level of sulfide in the biogas. This paper presents the results of a bioreactor study and of batch experiments that were performed to obtain better insight into the fate of sulfur compounds and oxygen during micro-aerobic sulfide oxidation. Introduction of a low airflow (0.7-0.9 m(3)m(-3)d(-1), corresponding to an O(2)/S molar ratio of 8-10) to a fluidized bed reactor fed with low-sulfate vinasse was sufficient to reduce the biogas H(2)S-content to an undetectable level. Sulfide was initially oxidized to elemental sulfur, thiosulfate and - most probably - polysulfide. Significant sulfate production did not occur. Bioreactor sludge sampled from the reactor after three weeks' micro-aerobic operation was much faster in oxidizing sulfur than bioreactor sludge sampled during fully anaerobic reactor operation. The reaction proceeded faster with increasing O(2)/sulfide ratios.

Anaerobiosis↗
PubMed2003

Isolation and characterization of a sulfur-oxidizing chemolithotroph growing on crude oil under anaerobic conditions.

Molecular approaches have shown that a group of bacteria (called cluster 1 bacteria) affiliated with the epsilon subclass of the class Proteobacteria constituted major populations in underground crude-oil storage cavities. In order to unveil their physiology and ecological niche, this study isolated bacterial strains (exemplified by strain YK-1) affiliated with the cluster 1 bacteria from an oil storage cavity at Kuji in Iwate, Japan. 16S rRNA gene sequence analysis indicated that its closest relative was Thiomicrospira denitrificans (90% identity). Growth experiments under anaerobic conditions showed that strain YK-1 was a sulfur-oxidizing obligate chemolithotroph utilizing sulfide, elemental sulfur, thiosulfate, and hydrogen as electron donors and nitrate as an electron acceptor. Oxygen also supported its growth only under microaerobic conditions. Strain YK-1 could not grow on nitrite, and nitrite was the final product of nitrate reduction. Neither sugars, organic acids (including acetate), nor hydrocarbons could serve as carbon and energy sources. A typical stoichiometry of its energy metabolism followed an equation: S(2-) + 4NO(3)(-) --> SO(4)(2-) + 4NO(2)(-) (Delta G(0) = -534 kJ mol(-1)). In a difference from other anaerobic sulfur-oxidizing bacteria, this bacterium was sensitive to NaCl; growth in medium containing more than 1% NaCl was negligible. When YK-1 was grown anaerobically in a sulfur-depleted inorganic medium overlaid with crude oil, sulfate was produced, corresponding to its growth. On the contrary, YK-1 could not utilize crude oil as a carbon source. These results suggest that the cluster 1 bacteria yielded energy for growth in oil storage cavities by oxidizing petroleum sulfur compounds. Based on its physiology, ecological interactions with other members of the groundwater community are discussed.

Anaerobiosis↗
PubMed2002

Atmospheric DMSO degradation in the gas phase: Cl-DMSO reaction. Temperature dependence and products.

The reactions of Cl atoms and ClO radicals with CH3-SOCH3 (DMSO) have been studied using the discharge flow method with direct detection of DMSO, CO, and products by mass spectrometry. The absolute rate constant at room temperature measured for reaction 1, (CH3)2SO + Cl --> products, was k(1) = (1.7 +/- 0.3) x 10(-11) cm3 molecule(-1) s(-1). For reaction 2, (CH3)2SO + ClO --> products, only an upper limit could be established, k(2) < or = 6 x 10(-14) cm3 molecule(-1) s(-1) Reaction 1 has been found to proceed through adduct formation and further decomposition involving the cleavage of the C-S bound. The pressure effect on the Cl-DMSO reaction from 0.5 to 3 Torr was negligible, and the temperature dependence in the range 273-335 K was also very slight. The results obtained are related to previous studies of sulfur compounds, and the atmospheric implications are also discussed in relation to the homogeneous sinks of DMSO. Tropospheric lifetimes of DMSO based on average Cl and ClO concentrations and the measured rate constants have been calculated showing that the contribution of reaction 1 must be of minor relevance in the marine boundary layer. Reaction 2 is so slow that it does not play any role within the atmospheric sulfur chemistry.

Air Pollutants↗
PubMed2004

Apparent redundancy of electron transfer pathways via bc(1) complexes and terminal oxidases in the extremophilic chemolithoautotrophic Acidithiobacillus ferrooxidans.

Acidithiobacillus ferrooxidans is an acidophilic chemolithoautotrophic bacterium that can grow in the presence of either the weak reductant Fe(2+), or reducing sulfur compounds that provide more energy for growth than Fe(2+). We have previously shown that the uphill electron transfer pathway between Fe(2+) and NAD(+) involved a bc(1) complex that functions only in the reverse direction [J. Bacteriol. 182, (2000) 3602]. In the present work, we demonstrate both the existence of a bc(1) complex functioning in the forward direction, expressed when the cells are grown on sulfur, and the presence of two terminal oxidases, a bd and a ba(3) type oxidase expressed more in sulfur than in iron-grown cells, besides the cytochrome aa(3) that was found to be expressed only in iron-grown cells. Sulfur-grown cells exhibit a branching point for electron flow at the level of the quinol pool leading on the one hand to a bd type oxidase, and on the other hand to a bc(1)-->ba(3) pathway. We have also demonstrated the presence in the genome of transcriptionally active genes potentially encoding the subunits of a bo(3) type oxidase. A scheme for the electron transfer chains has been established that shows the existence of multiple respiratory routes to a single electron acceptor O(2). Possible reasons for these apparently redundant pathways are discussed.

Acidithiobacillus↗
PubMed2003

Aroma extract dilution analysis of Cv. Marion (Rubus spp. hyb) and Cv. Evergreen (R. laciniatus L.) blackberries.

Cultivar Marion and Evergreen blackberry aromas were analyzed by aroma extract dilution analysis. Sixty-three aromas were identified (some tentatively) by mass spectrometry and gas chromatography-retention time; 48 were common to both cultivars, and 27 have not been previously reported in blackberry fruit. A comparison of cultivars shows that both have comparable compound types and numbers but with widely differing aroma impacts, as measured by flavor dilution (FD) factors. Ethyl 2-methylbutanoate, ethyl 2-methylpropanoate, hexanal, furanones (2,5-dimethyl-4-hydroxy-3-(2H)-furanone, 2-ethyl-4-hydroxy-5-methyl-3-(2H)-furanone, 4-hydroxy-5-methyl-3-(2H)-furanone, 4,5-dimethyl-3-hydroxy-2-(5H)-furanone, and 5-ethyl-3-hydroxy-4-methyl-2-(5H)-furanone), and sulfur compounds (thiophene, dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, 2-methylthiophene, and methional) were prominent in Evergreen (FD 512-2048). Except for ethyl 2-methylpropanoate, these same compounds were also prominent in Marion, but the FD factors varied significantly (FD 8-256) from Evergreen. The aroma profile of blackberry is complex, as no single volatile was unanimously described as characteristically blackberry.

Chromatography, Gas↗
PubMed2006

Geomicrobiological exploration and characterization of a novel deep-sea hydrothermal system at the TOTO caldera in the Mariana Volcanic Arc.

Novel hydrothermal activities accompanying effluent white smokers and elemental sulfur chimney structures at the north-east lava dome of the TOTO caldera depression in the Mariana Volcanic Arc have been explored and characterized by geochemical and microbiological surveys. White smoker hydrothermal fluids were observed in the potential hydrothermal activity centre of the field and represented the maximal temperature of 170 degrees C and the lowest pH of 1.6. The chimney structures, all consisting of elemental sulfur (sulfur chimney), were also unique to the TOTO caldera hydrothermal field. Microbial community structures in a sulfur chimney and its formation hydrothermal fluid with a high concentration of hydrogen sulfide (15 mM) have been investigated by culture-dependent and -independent analyses. 16S rRNA gene clone analysis and fluorescence in situ hybridization (FISH) analysis revealed that epsilon-Proteobacteria dominated the microbial communities in the sulfur chimney structure and formed a dense microbial mat covering the sulfur chimney surface. Archaeal phylotypes were consistently minor components in the communities and related to the genera Thermococcus, Pyrodictium, Aeropyrum, and the uncultivated archaeal group of 'deep-sea hydrothermal vent euryarchaeotal group'. Cultivation analysis suggested that the chemolithoautotrophs might play a significant ecological role as primary producers utilizing gas and sulfur compounds provided from hydrothermal fluids.

Archaea↗
PubMed2005

X-ray absorption near-edge structure analysis of arsenic species for application to biological environmental samples.

Arsenic is an element that is ubiquitous in the environment and is known to form compounds with toxic, even carcinogenic properties. Arsenic toxicity is a function of its chemical form (species). Identification of arsenic species is necessary to accurately determine the transformation and fate of arsenicals as well as the actual risk posed by arsenic contamination. We report X-ray absorption near-edge structure (XANES) measurements of 16 biologically important arsenic compounds. Solid and aqueous standards were studied for differences in XANES spectral features, white line positions, stability during exposure to the beam, and stability between two beam exposures separated by 48 h. Samples containing As(III) (11870.0-11871.7+/-0.5 eV) and As(V) (11872.6-11875.3+/-0.5 eV) were easily distinguished by white line energies and could be further subdivided into a total of seven groups. Valuable examples include As(III)-sulfur compounds (11870.0+/-0.5 eV), arsenobetaine and arsenocholine (11872.6+/-0.5 eV), and a dimethyl arsinyl riboside (11873.3+/-0.5 eV). A growing number of environmental and biological studies use X-ray absorption spectroscopy (XAS) results to complement their more traditional analyses. Results provided here are intended to help make XAS more accessible to new users interested in the study of arsenic in the environment.

Arsenic↗
PubMed2004

Comparison of the chemopreventive efficacies of garlic powders with different alliin contents against aflatoxin B1 carcinogenicity in rats.

Garlic (Allium sativum) is well known for its beneficial effects on health and particularly for its chemopreventive potential against cancer. The present study was designed to compare the chemopreventive efficacies of several garlic powders with various levels of alliin, a precursor of active sulfur compounds. For this purpose we used the medium-term hepatocarcinogenesis protocol (resistant hepatocyte model), which allows the detection of preneoplasic foci expressing the placental form of glutathione S-transferase (GST-P) as an end-point. Rats were fed diets containing three garlic powders (5% of the diet) with various alliin contents for 3 weeks. Garlic powders were obtained from bulbs grown on soils with different levels of sulfur fertilization. During the period of garlic feeding hepatocarcinogenesis was initiated by administration of 10 i.p. injections of 0.025 mg/kg body weight aflatoxin B1 (AFB1). The rats were later submitted to 2-acetylaminofluorene treatment and partial hepatectomy, and GST-P foci were detected and quantified. Consumption of diets containing garlic powders decreased the appearance and size of hepatic GST-P foci. A strong reduction was observed in rats fed garlic containing the highest level of alliin. In addition, increased alliin content of the garlic powder was associated with a proportional decrease in the number and area of preneoplastic foci. Elsewhere, garlic powder ingestion increased hepatic ethoxyresorufin deethylase, glutathione S-transferase and UDP glucuronosyl transferase activities while no modification of nifedipine oxidase activity was found. We also observed an increase in the levels of GST A5 and AFB1 aldehyde reductase. It is suggested that garlic partly exerts its anticarcinogenic effects through increasing enzymes involved in AFB1 detoxification. This study highlights the possibility of controlling the cultivation conditions to improve the chemopreventive efficacy of garlic.

Aflatoxin B1↗
PubMed2004

Effect of the type of frying culinary fat on volatile compounds isolated in fried pork loin chops by using SPME-GC-MS.

The effect of the type of frying culinary fat (olive oil, sunflower oil, butter, and pig lard) on volatile compounds isolated from fried pork loin chops (m. Longissimus dorsi) was measured by SPME-GC-MS. Frying modified the fatty acid composition of lipids from pork loin chops, which tended to be similar to that of the culinary fat used to fry. Volatile compounds formed from the oxidation of fatty acids increased, such as aldehydes, ketones, alcohols, and hydrocarbons. Besides, each culinary fat used modified the volatile profiles in fried meat differently. Sunflower oil-fried pork loin chops presented the highest aldehyde aliphatic content, probably due to their highest content of polyunsaturated acids. Hexanal, the most abundant aldehyde in fried samples, presented the most elevated content in sunflower oil-fried pork loin chops. In addition, these samples presented more heterocyclic compounds from the Maillard reaction than other fried samples. Volatiles detected in olive oil-fried pork loin chops were mainly lipid-derived compounds such as pentan-1-ol, hexanal, hept-2-enal, nonanal, decanal, benzaldehyde, and nonan-2-one. Butter-fried pork loins were abundant in ketones with a high number of carbons (heptan-2-one, nonan-2-one, undecan-2-one, tridecanone, and heptadecan-2-one). Pig lard-fried pork loin chops presented some Strecker aldehydes isolated in only these samples, such as 2-methylbutanal and 3-(methylthio)propanal, and a sulfur compound (dimethyl disulfide) related to Strecker aldehydes.

Alcohols↗
PubMed1982

Emission of hydrogen sulfide from sulfur dioxide-fumigated pine trees.

Pine (Pinus silvestris L.) trees subjected to relatively low concentration of SO(2) in the field emit H(2)S from the needles, as demonstrated by gas chromatographic analysis after preconcentration on a molecular sieve. H(2)S is the only reduced sulfurous compound emitted from SO(2) fumigated leaves. The emission is light and SO(2) concentration dependent. Pine trees in the field and in laboratory experiments continue to emit H(2)S several hours after the termination of prolonged SO(2) fumigation. The maximum emission rates observed from pine trees in the field and in laboratory experiments, 14 and 20 nanomoles per milligram chlorophyll per hour respectively, are about the activity expected for the sulfur assimilation pathway in the chloroplasts.

Journal Article↗
PubMed1985

Lung injury in guinea pigs caused by multiple exposures to submicron zinc oxide mixed with sulfur dioxide in a humidified furnace.

Sulfur dioxide, water vapor, and ultrafine particles rich in oxides of zinc and other surface-deposited trace elements are important products of coal combustion. In order to study the toxicity of zinc oxide generated under conditions simulating combustion, guinea pigs were exposed in a nose-only apparatus for 3 h on 6 consecutive days to 6 mg/m3 of submicron zinc oxide particles (count median diameter of 0.05 micron, sigma g 2.0), which were generated in a humid furnace and mixed with 1 ppm sulfur dioxide. The exposures caused increases in lung weight and [3H] thymidine labeling index of terminal bronchiolar cell nuclei and inflammation of the proximal portion of the alveolar duct. The lung weights and labeling index had returned to normal and inflammatory changes had nearly resolved by 72 h after the last exposure. Total lung capacity, vital capacity, functional residual volume, alveolar volume, and diffusing capacity for carbon monoxide were decreased following exposure and had not returned to normal by 72 h after the last exposure. Large airways were not affected by the repeated exposures, as indicated by normal morphology of trachea and bronchi, unchanged secretory cell concentration, and unaltered epithelial permeability to horseradish peroxidase. These results are essentially identical to changes we reported in guinea pigs exposed to zinc oxide alone, suggesting that surface-deposited sulfur compounds, which are important determinants of the response to a single exposure to these ultrafine particles, become less important as exposure progresses.

Animals↗
PubMedDate not supplied

Sulfur metabolism in bacteria associated with cheese.

Metabolism of sulfur in bacteria associated with cheese has long been a topic of interest. Volatile sulfur compounds, specifically methanethiol, are correlated to desirable flavor in Cheddar cheese, but their definitive role remains elusive. Only recently have enzymes been found that produce this compound in bacteria associated with cheese making. Cystathionine beta- and gamma-lyase are found in lactic acid bacteria and are capable of producing methanethiol from methionine. Their primary function is in the metabolism of cysteine. Methionine gamma-lyase produces methanethiol from methionine at a higher efficiency than the cystathionine enzymes. This enzyme is found in brevibacteria, bacilli, and pseudomonads. Addition of brevibacteria containing this enzyme improves Cheddar cheese flavor. Despite recent progress in sulfur metabolism more information is needed before cheese flavor associated with sulfur can be predicted or controlled.

Amino Acids, Sulfur↗
PubMedDate not supplied

Desulfurization of diesel oils by a newly isolated dibenzothiophene-degrading Nocardia sp. strain CYKS2.

A dibenzothiophene (DBT)-degrading bacterial strain was isolated from dyeing industry wastewater and identified as Nocardia sp. CYKS2. The newly isolated bacterial strain Nocardia sp. CYKS2 was able to convert DBT to 2-hydroxybiphenyl (2-HBP) as the dead-end metabolite through a sulfur-specific pathway. Other organic sulfur compounds, such as thiophene derivatives, thiazole derivatives, sulfides, and disulfides were also desulfurized by Nocardia sp. CYKS2. In batch culture, 0.2 mM DBT was completely desulfurized in 60 h. After DBT was depleted, neither cell growth nor 2-HBP production was observed. When a model oil which DBT was dissolved in hexadecane was treated with growing cells, DBT was desulfurized from 10 mM to about 2 mM in 80 h. In this case, desulfurization rate was 0.279 mg-sulfur/(L-dispersion.h), which was about 2.5 times higher than that in the previous case of batch culture. When diesel oil was treated, the sulfur content decreased from 0.3 to 0.24 wt % in 48 h. A volumetric phase ratio of oil to water was 1/10 in this case. The sulfur decreased from 0.3 to 0.2 wt % in 48 h, when the volumetric phase ratio was 1/20. The desulfurization rates were 0.909 and 0.992 mg-sulfur/(L-dispersion.h), respectively.

Biodegradation, Environmental↗
PubMed1983

Role of o-acetylserine in hydrogen sulfide emission from pumpkin leaves in response to sulfate.

In the presence of excess sulfate, cysteine synthesis in pumpkin (Cucurbita pepo) leaves is not limited by sulfate reduction, but by the availability of O-acetylserine. Feeding of O-acetylserine or its metabolic precursors S-acetyl-coenzyme-A and coenzyme A to leaf discs enhanced the incorportion of [(35)S]sulfate into reduced sulfur compounds, mainly into cysteine, at the cost of lowered H(2)S emission; the uptake and reduction of sulfate is not affected by these treatments. beta-Fluoropyruvate, an inhibitor of the generation of S-acetyl-coenzyme A via pyruvate dehydrogenase, stimulated H(2)S emission in response to sulfate. This stimulation is overcompensated by addition of O-acetylserine, S-acetyl-coenzyme A, or coenzyme A. These results indicate that, in the presence of high amounts of sulfate, excess sulfur is reduced and emitted as H(2)S into the atmosphere. The H(2)S emitted seems to be produced by liberation from a precursor of cysteine rather than by cysteine desulfhydration.

Journal Article↗