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PubMedDate not supplied

[Microbiological processes of the carbon and sulfur cycle in cold methane seeps in the North Atlantic].

Functioning of microbial communities in surface sediments of the Haakon Mosby underwater mud volcano (lat. 72 degrees N) and in gas seepage fields of the Vestnesa Ridge was investigated using Mir-1 and Mir-2 deep-sea submersibles during the 40th expedition of the research vessel Academician Mstislav Keldysh. Large areas of sedimentary deposits of the Haakon Mosby mud volcano (HMMV) and pockmarks of the Vestnesa Ridge (VR) are covered with bacterial mats 0.1 to 0.5 cm thick. The microbial community making up bacterial mats of the HMMV was predominated by large filamentous bacteria with filaments measuring up to 100 microns in length and 2 to 8 microns in width. The occurrence of rosettes allowed the observed filamentous bacteria to be referred to the morphologically similar genera Leucothrix or Thiothrix. Three morphological types of filamentous bacteria were identified in bacterial mats covering VR pockmarks. Filaments of type one are morphologically similar with representatives of the genera Thioploca or Desmanthos. Type two filaments had numerous inclusions of sulfur and resembled representatives of the genus Thiothrix. The third morphological type was constituted by single filaments made up of tightly connected disk-like cells and can, apparently, be assigned to the genus Beggiatoa. The rates of methane oxidation (up to 1570 microliters C/(dm3 day)) and sulfate reduction (up to 17 mg S/(dm3 day)) measured in surface sediments of HMMV and VR were close to the maximum rates of these processes observed in badly polluted regions of the northwestern shelf of the Black Sea. High rates of microbiological processes correlated with the high number of bacteria. The rate of methane production in sediments studied was notably lower and ranged from 0.1 to 3.5 microliters CH4/(dm3 day). Large areas of the HMMV caldera were populated by pogonophoras, represented by the two species, Sclerolinum sp. and Oligobrachia sp. The mass development of Sclerolinum sp. in the HMMV caldera was by the activity of aerobic methane-oxidizing bacteria localized inside the cells of these animals. Bacterial cells were also found in the trophosome tissue of Oligobrachia sp., but in cells of these bacteria, we did not observe the membrane structures typical of methanotrophs. The localization pattern of pogonophoras on the surface of reduced sediments suggests that the predominant bacteria in Oligobrachia tissues are sulfur-oxidizing endosymbionts.

Bacteria↗
PubMed2002

[Determination of chloroform and tetrachloro-methane in water with capillary column-microECD].

The method of determination of chloroform and tetrachloro-methane in water with capillary column-microECD had better and wider linear range and lower detection limit. At the range of 0-10 micrograms/L chloroform and 0-1 microgram/L tetrachloro-methane, the regression equation were calculated as Y = 1.959X + 4.816 (r = 0.9910) and Y = 3.947X + 42.58 (r = 0.9970). The lowest detection limit were 0.1032 microgram/L chloroform and 0.01219 microgram/L tetrachloro-methane. This method not only simplified the operating processes, but also increase the sensitivity, and reavled better precision and accuracy.

Carbon Tetrachloride↗
PubMedDate not supplied

Screening for restriction endonucleases in methane-oxidizing bacteria.

51 methane-oxidizing bacteria strains such as Methylomonas methanica, M. rubra, Methylococcus capsulatus, M. thermophilus, M. luteus, M. ucrainicus, M. whittenburyi, Methylosinus trichosporium, M. sporium, Methylocystis parvus isolated from various ecological niches and geographical regions of the Ukraine and also the strains received from R. Whittenbury and Y. Heyer were screened for restriction endonucleases. Type II restriction endonucleases were detected in IMV B-3112 (= 12 b), IMV B-3027 (= 26), IMV B-3019 (= 9 c), IMV B-3017 (= 17 c), IMV B-3226 (= 26 v), IMV B-3033 (= Y), IMV B-3100 (= 100) and IMV B-3494 (= 1E494). The results obtained were indicative of relatively high frequency of restriction enzymes occurrence in methane-oxidizing bacteria. There were Kpn I (Asp 7181) restriction endonuclease isoschizomers in crude extracts of IMV B-3112, B-3017, B-3019, B-3027 isolated from fresh-water silt as well as in IMV B-3226 strain isolated from waste-water silt. Although these isolates had bee previously considered as untypical strains of M. ucrainicus, more detailed study of their properties allowed placing them with Methylovarius luteus (= Methylococcus luteus). IMV B-3494 strain was identified as Methylococcus capsulatus. Strain IMV B-3033 had earlier been allocated to Methylovarius whittenburyi (= Methylococcus whittenburyi). Specificity of restriction endonucleases of this strain was not tested. Therefore, for the first time restriction endonucleases were detected in methane-oxidizing bacteria. 8 strains (3 species) among 51 strains (13 species) were found to produce restriction endonucleases displaying three different types of specificity in the least. Producers of restriction endonucleases having Kpn I (Asp 7181) specificity were isolated from different water and silt samples of the Dnieper flood-land more than 20 years ago.

DNA Restriction Enzymes↗
PubMed1986

Sensitizing capacity of 4,4(1)-dihydroxy-(hydroxymethyl)-diphenyl methanes in the guinea pig.

The sensitizing capacity of 4,4(1)-dihydroxy-3-(hydroxymethyl)-diphenyl methane (4,4(1)-H-3-HPM), 4,4(1)-dihydroxy-3,3(1)-di-(hydroxymethyl)-diphenyl methane 4,4(1)-H-3,3(1)--HPM) and 4,4(1)-dihydroxy-3,5-di-(hydroxymethyl)-diphenyl methane (4,4(1)-H-3,5-HPM) was investigated using the guinea pig maximization text. These compounds are known contact sensitizers in phenol-formaldehyde resins (P-F-R). The study was performed in order to assess and compare the degrees of the sensitizing capacities of these chemically related substances. The animals were also rechallenged with the sensitizer and 5 related compounds, all known to be present in P-F-R, in order to study the cross-reaction patterns. 4,4(1)-H-3,3(1)-HPM was demonstrated to be a strong sensitizer and 4,4(1)-H-3-HPM and 4,4(1)-H-3,5-HPM to be moderate sensitizers. With 4,4(1)-H-3,3(1)-HPM as the sensitizer, 4,4(1)-H-3-HPM and 4,4(1)-H-3,5-HPM were cross-reacting substances and simple methylol phenols were possible cross-reacting compounds. Possible cross-reactivity were indicated between the three 4,4(1)-H-HPM when 4,4(1)-H-3-HPM and 4,4(1)-H-3,5-HPM respectively were the sensitizers. The chemical investigation by high pressure liquid chromatography indicated that the compounds tested were pure and separable.

Animals↗
PubMed1988

The biosynthesis and assembly of protein A of soluble methane monooxygenase of Methylococcus capsulatus (Bath).

Protein A of soluble methane monooxygenase (EC 1.14.13.25) of Methylococcus capsulatus (Bath) is the hydroxylase component of the enzyme complex, capable of inserting an atom of oxygen into methane. The protein possesses an unusual non-heme iron center consisting of two mu-hydroxo-bridged antiferromagnetically coupled iron atoms. It was possible to remove the iron center of protein A by subjecting the protein to freeze/thaw cycles or by dialysis against 8-hydroxyquinoline. Incubation of iron-depleted protein A with iron-EDTA and dithiothreitol resulted in the reassembly of the iron center of protein A as judged by restoration of enzyme activity (typically approximately 3 times the original activity) and by ESR spectroscopic methods. Reconstitution was inhibited by a number of metal ions, but none of the metals tested proved capable of replacing iron in the oxidation of methane. A number of iron-chelating agents exhibited weak inhibition of reconstitution. The KM(app) for iron in the reconstitution reaction was 133 microM. In vitro translation of total RNA isolated from M. capsulatus (Bath) produced protein A subunits equal to the native molecular weight, suggesting that there is no precursor form of this protein. Addition of the in vitro translated protein A to the reconstitution system resulted in low levels of hydroxylase activity suggesting that the subunits of protein A are self-assembling, a supposition supported by the presence of only one protein band on nondenaturing gels. Taken together, these data suggest that the subunits of protein A are synthesized in their native, mature form and self-assemble into an apoprotein A, into which the iron center is inserted.

Cations, Divalent↗
PubMed1985

Contact allergy to dihydroxydiphenyl methanes (bisphenol F).

16 patients with contact allergy to phenol-formaldehyde resins (P-F-R) were patch tested with 3 dihydroxydiphenyl methanes (bisphenol F). The chemical investigation by high pressure liquid chromatography indicated that the dihydroxydiphenyl methanes (HPM) were pure and separable. 9 patients reacted to at least one HPM and all these gave positive test responses to 2,4(1)-HPM. 3 patients reacted simultaneously to 2,4(1)-HPM and 4,4(1)-HPM and one of these 3 patients reacted simultaneously to all 3 HPM. No positive test responses were noted in 100 controls. 8 of the 9 patients were also patch tested with 8 compounds with similar chemical structures to the HPM. Possible cross-reactions were observed in 2 patients for 4-hydroxydiphenyl methane, 4,4(1)-dihydroxydiphenyl-2-propane (bisphenol A) and diethylstilbestrol. The 3 reported sensitizers may, theoretically, be generated during the manufacture of P-F-R. 2,4(1)-HPM and 4,4(1)-HPM have been demonstrated and there have been indications of 2,2(1)-HPM in the P-F-R used in the routine test series at the department.

Benzhydryl Compounds↗
PubMed2003

Gas-phase reaction of CCl2F2 (CFC-12) with methane.

Gas-phase reaction of CFC-12 (CCl2F2) with methane was carried out in a plug flow reactor over the temperature range of 873-1123 K. The major organic halocarbons formed during the reaction were C2F4, C2H2F2, CHClF2, CH3Cl, C3H2F6 and CCl3F. The formation of all products except C2H2F2 decreased with temperature, while the selectivity to C2H2F2 (difluoroethylene) increased with temperature and reached approximately 80% at 1123 K. Under these reaction conditions, methane acts as hydrogen and carbon source, resulting in the formation of an unsaturated C2 hydrofluorocarbon from two C1 precursors.

Chlorofluorocarbons, Methane↗
PubMed2004

Standards development of global warming gas species: methane, nitrous oxide, trichlorofluoromethane, and dichlorodifluoromethane.

Environmental scientists from federal agencies, such as the National Oceanic and Atmospheric Administration (NOAA), and academia have long suspected that increasing anthropogenic inputs of various trace gases into the atmosphere can cause changes in the earth's climate and protective ozone layer. Nitrous oxide and methane, cited in the Kyoto Protocol, as well astrichlorofluoromethane (CFC-11) and dichlorodifluoromethane (CFC-12), cited in the Montreal Protocol, are all greenhouse gases and are implicated in the destruction of the stratospheric ozone layer. The lack of national standards prompted research to determine the feasibility of preparing accurate and stable standards containing these four compounds. Development of these standards would support the measurement of these species by those in the atmospheric research community not having their own source of standards. A suite of eight primary gas standards containing methane, nitrous oxide, CFC-11, and CFC-12 in a balance of air were prepared gravimetrically to bracket the ambient atmospheric concentrations. The combined uncertainties (uc) were calculated from error propagation analysis that included the weighing data from the gravimetric preparation and other sources of error such as the purity analysis of the compounds and air matrix. The expanded uncertainties (U) for the gravimetric standards were < 0.5% as calculated from the equation U = kuc, where the coverage factor k is equal to 2 for a 95% confidence interval. Analyses of the suite of standards by gas chromatography with flame-ionization and electron capture detection resulted in average absolute residuals of < 0.25% from regression models. The NIST suite of eight gravimetric standards was used to determine the concentrations in two standardsfrom NOAA. Those analyses resulted in bias across the two laboratories of < or = 2.1%.

Air Pollutants↗
PubMed1993

Antifungal agents, II: Synthesis and antifungal activities of aryl-1H-pyrrol-2-yl-1H-imidazol-1-yl-methane derivatives with unsaturated chains.

The synthesis and antifungal activities of aryl-1H-pyrrol-2-yl-1H-imidazol-1-yl-methanes having allyl, crotyl, and acrylate chains linked to the N-pyrrole atom and substituted at phenyl ring by Cl, F, CH3, and NO2 groups are reported. In vitro tests against Candida albicans and Candida spp. showed 2,4-dichlorophenyl-1-allyl-1H-pyrrol-2-yl-1H-imidazol-1-yl-methane to be the most potent derivative with activities comparable to those of ketoconazole and slightly inferior to those of bifonazole and miconazole. Some structure-activity relationships are discussed.

Antifungal Agents↗
PubMed2006

Activation barriers for DNA alkylation by carcinogenic methane diazonium ions.

Methylation reactions of the DNA bases with the methane diazonium ion, which is the reactive intermediate formed from several carcinogenic methylating agents, were examined. The SN2 transition states of the methylation reactions at N7, N3, and O6 of guanine; N7, N3, and N1 of adenine; N3 and O2 of cytosine; and O2 and O4 of thymine were calculated using the B3LYP density functional method. Solvation effects were examined using the conductor-like polarizable continuum method and the combined discrete/SCRF method. The transition states for reactions at guanine N3, adenine N7, and adenine N1 are influenced by steric interactions between the methane diazonium ion and exocyclic amino groups. Both in the gas phase and in aqueous solution, the methylation reactions at N atoms have transition states that are looser, and generally occur earlier along the reaction pathways than reactions at O atoms. The forming bonds in the transition states in water are 0.03 to 0.13 A shorter than those observed in the gas phase, and the activation energies are 13 to 35 kcal/mol higher. The combined discrete/SCRF solvation energy calculations using base-water complexes with three water molecules yield base solvation energies that are larger than those obtained from the CPCM continuum method, especially for cytosine. Reactivities calculated using barriers obtained with the discrete/SCRF method are consistent with the experimentally observed high reactivity at N7 of guanine.

Alkylation↗
PubMed2006

Methane activation by chromium oxide cations in the gas phase: a theoretical study.

Density Functional Theory, in its B3LYP formulation, was used to explore quantitative details of the potential energy hypersurfaces for the C-H bond activation reaction of methane by chromium dioxide cation. Both doublet ground and quartet excited states of the cation were considered, and all the minima and transition states localized along the paths leading to the formation of the experimentally observed products were characterized. All the calculated paths involve spin inversions that decrease the barrier heights of the involved transition states but do not play a significant role. Reaction pathways were also studied employing the nonhybrid BP86 functional, the reparametrized B3LYP* functional, and the CCSD(T) approach. Because other examples in the literature indicate that sequential ligation enhances the reactivity of bare transition metals cations, the state-selective reactivity of the chromium monoxide cation with respect to methane was also investigated and compared with that of the bare cation.

Cations↗
PubMed1999

Effects of heavy metals on methane production in tropical rice soils.

In a laboratory incubation study, the effect of select heavy metals on methane (CH(4)) production in three rice soils was investigated under flooded conditions. Heavy metals behaved differently in their effect on methanogenesis in different soils and methane-producing bacteria. Cd, Cu, and Pb inhibited CH(4) production in all the soils. Zn stimulated CH(4) production in the alluvial soil, but inhibited it in laterite and acid sulfate soils. Cr effectively inhibited CH(4) production in the alluvial soil, but stimulated it in laterite and acid sulfate soils. The stimulatory effect of Zn and the inhibitory effect of Cr on methanogenesis in alluvial soil were attributed to their stimulation or inhibition of methanogenic bacterial population.

Bacteria↗
PubMed1987

Evidence for methane and ammonia in the coma of comet P/Halley.

Methane and ammonia abundances in the coma of Halley are derived from Giotto IMS data using an Eulerian model of chemical and physical processes inside the contact surface to simulate Giotto HIS ion mass spectral data for mass-to-charge ratios (m/q) from 15 to 19. The ratio m/q = 19/18 as a function of distance from the nucleus is not reproduced by a model for a pure water coma. It is necessary to include the presence of NH3, and uniquely NH3, in coma gases in order to explain the data. A ratio of production rates Q(NH3)/Q(H2O) = 0.01-0.02 results in model values approximating the Giotto data. Methane is identified as the most probable source of the distinct peak at m/q = 15. The observations are fit best with Q(CH4)/Q(H2O) = 0.02. The chemical composition of the comet nucleus implied by these production rate ratios is unlike that of the outer planets. On the other hand, there are also significant differences from observations of gas phase interstellar material.

Ammonia↗
PubMed1977

Autonomous growth fluctuations of the methane oxidizing bacterial strain M 102 in batch and continuous culture.

The growth rates of the methane oxidizing strain M 102 were unstable. In unlimited batch cultures they ranged from 0 to 1.4 d-1 with most frequent values around 0.25 d-1. The yield coefficients were between 0.1 and 1.6 mg dry weight per mg methane and varied from 1.1 to 0.4 even in a continuous culture with the limiting substrate in the gas phase. It was possible to prove intermittent release and uptake of organic compounds by the definition of a "net" yield coefficient and its theoretical boundaries. The response of the fluctuations to varying dilution frequencies and culture volumes showed analogies to controlled systems. The simultaneous variations in the age distribution and in the excretion pattern revealed the dependence of the dividing stages on a product of the young cells. The mathematical description of the findings suggests that the young cells favor division at their own disadvantage. The consequent autonomous synchronisations are the reason for the unstable growth rates of strain M 102.

Bacteria↗
PubMed1980

Characterization of an acetate-decarboxylating, non-hydrogen-oxidizing methane bacterium.

A methanogenic bacterium, commonly seen in digested sludge and referred to as the "fat rod" or Methanobacterium soehngenii, has been enriched to a monoculture and is characterized. Cells are gramnegative, non-motile and appear as straight rods with flat ends. They form filaments which can grow to great lengths. The structure of the outer cell envelop is similar to Methanospirillum hungatii. The organism grows on a mineral salt medium with acetate as the only organic component. Acetate is the energy source, and methane is formed exclusively from the methyl group. Acetate and carbon dioxide act as sole carbon source and are assimilated in a molar ratio of about 1.9:1. The reducing equivalents necessary to build biomass from these two precursors are obtained from the total oxidation of some acetate. Hydrogen is not used for methane formation and is not needed for growth. Formate is cleaved into hydrogen and carbon dioxide. Coenzyme M was found to be present at levels of 0.35 nmol per mg of dry cells and F420 amounted to 0.55 microgram per mg protein. The mean generation time was 9 days at 33 degrees C.

Acetates↗
PubMed1979

Complete degradation of carbohydrate to carbon dioxide and methane by syntrophic cultures of Acetobacterium woodii and Methanosarcina barkeri.

Methanosarcina barkeri (strain MS) grew and converted acetate to CO2 and methane after an adaption period of 20 days. Growth and metabolism were rapid with gas production being comparable to that of cells grown on H2 and CO2. After an intermediary growth cycle under a H2 and CO2 atmosphere acetate-adapted cells were capable of growth on acetate with formation of methane and CO2. When acetate-adapted Methanosarcina barkeri was co-cultured with Acetobacterium woodii on fructose or glucose as substrate, a complete conversion of the carbohydrate to gases (CO2 and CH4) was observed.

Acetates↗
PubMed1985

Methanosphaera stadtmaniae gen. nov., sp. nov.: a species that forms methane by reducing methanol with hydrogen.

Methanosphaera stadtmaniae is a non-motile, Gram-positive spherical-shaped organism that obtains energy for growth by using hydrogen to reduce methanol to methane. It does not produce methane from hydrogen and carbon dioxide, formate, acetate or methylamines and cannot grow with hydrogen and carbon monoxide, nitrate, fumarate, sulfate or choline. Its pH optimum is 6.5 to 6.9 and its temperature optimum is 36 degrees to 40 degrees C. It is not inhibited by bile salts, inhibitors of the synthesis of folic acid coenzymes, cephalothin or clindamycin but is inhibited by metronidazole, bacitracin, monensin, lasalocid, or bromoethanesulfonate. It requires acetate, carbon dioxide, isoleucine, ammonium, and thiamin for growth and biotin is stimulatory. It does not contain cytochromes and the mol % G + C of its DNA is 25.8. The composition of its cell wall and 16 S rRNA and its immunological fingerprint are consistent with characterization of the organism as a member of a new genus of the family Methanobacteriaceae. The habitat of the type strain is the human large intestine.

DNA, Bacterial↗
PubMedDate not supplied

High frequency discharge experiment. I: Formation of organic compounds from methane and ammonia.

Investigations of the synthesis of organic compounds from methane and ammonia were carried out by using high frequency discharges. The radical of CN was observed in the early phase of the discharge. Therefore it is considered that the CN radical contributes to the successive reaction steps. An important intermediate, a tetramer of hydrogen cyanide was observed to be formed at room temperature. The amounts of this compound progressively increased with time. It was speculated that the purines which were identified in the refluxed sample were synthesized through the above tetramer. Compounds which are thought to be heterocyclic (max:250-265nm) were initially formed in the sample trapped at liquid nitrogen temperature. After hydrolysis with hydrochloric acid, Gly, Asp Ala, etc. were observed in the sample. Overall yield of organic compounds was estimates at 5-6% based on input carbon of methane.

Ammonia↗