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PubMed1995

Bacterial growth with chlorinated methanes.

Chlorinated methanes are important industrial chemicals and significant environmental pollutants. While the highly chlorinated methanes, trichloromethane and tetrachloromethane, are not productively metabolized by bacteria, chloromethane and dichloromethane are used by both aerobic and anaerobic methylotrophic bacteria as carbon and energy sources. Some of the dehalogenation reactions involved in the utilization of the latter two compounds have been elucidated. In a strictly anaerobic acetogenic bacterium growing with chloromethane, an inducible enzyme forming methyltetrahydrofolate and chloride from chloromethane and tetrahydrofolate catalyzes dehalogenation of the growth substrate. A different mechanism for the nucleophilic displacement of chloride is observed in aerobic methylotrophic bacteria utilizing dichloromethane as the sole carbon and energy source. These organisms possess the enzyme dichloromethane dehalogenase which, in a glutathione-dependent reaction, converts dichloromethane to inorganic chloride and formaldehyde, a central metabolite of methylotrophic growth. Sequence comparisons have shown that bacterial dichloromethane dehalogenases belong to the glutathione S-transferase enzyme family, and within this family to class Theta. The dehalogenation reactions underlying aerobic utilization of chloromethane by a pure culture and anaerobic growth with dichloromethane by an acetogenic mixed culture are not known. It appears that they are based on mechanisms other than nucleophilic attack by tetrahydrofolate or glutathione.

Bacteria↗
PubMed1987

Rest and exercise cardiac output and diffusing capacity assessed by a single slow exhalation of methane, acetylene, and carbon monoxide.

To study rest and exercise pulmonary capillary blood flow (Qc) and diffusing capacity (DLexh) assessed by the rapid analysis of methane, acetylene, and carbon monoxide during a single, slow exhalation, we evaluated 36 subjects during first-pass radionuclide angiography (RNA). At rest (N = 36) and at exercise (N = 21) there was no difference in the respective measurements of cardiac output (Qc = 6.0 +/- 1.7 and CORNA = 6.9 +/- 2.5 at rest; Qc = 13.7 +/- 3.2 and CORNA = 14.5 +/- 4.1 at exercise, L/min, mean +/- SD, r = .80). Mild maldistribution of ventilation, as manifested by an increased phase 3 alveolar slope for methane (CH4 slope), did not significantly influence the results. CH4 slope and DLexh did increase significantly with exercise, while total lung capacity remained unchanged (CH4 slope: 6.2 +/- 5.0 vs 12.5 +/- 6.8% delta CH4/L, mean +/- SD, p less than 0.001; Dsb: 27.7 +/- 9.2 vs 42.0 +/- 17.9 ml/min/mm Hg, mean +/- SD, p less than 0.001; TLC: 5.47 +/- .20 vs 5.96 +/- 1.20 L, mean +/- SD). DLexh was related to CORNA (r = .68) and RNA stroke volume (r = .50). Qc was significantly less than CORNA in the subset of studies with valvular regurgitation (VHD) (N = 7). On the other hand, Qc was significantly greater than CORNA in the setting of coronary artery disease (CAD) and severe wall motion abnormalities (N = 7). These differences may be attributed to regurgitant fractions in VHD, and the influence of wall motion abnormalities on the estimation of left ventricular volume by the area-length method in CAD. These two noninvasive methods compare well at rest and exercise in clinical subjects and may provide complementary information in certain cardiopulmonary diseases.

Acetylene↗
PubMed2004

Study on methane fermentation and production of vitamin B12 from alcohol waste slurry.

We studied biogas fermentation from alcohol waste fluid to evaluate the anaerobic digestion process and the production of vitamin B12 as a byproduct. Anaerobic digestion using acclimated methanogens was performed using the continuously stirred tank reactor (CSTR) and fixed-bed reactor packed with rock wool as carrier material at 55 degrees C. We also studied the effects of metal ions added to the culture broth on methane and vitamin B12 formation. Vitamin B12 production was 2.92 mg/L in the broth of the fixed-bed reactor, twice that of the CSTR. The optimum concentrations of trace metal ions added to the culture liquid for methane and vitamin B12 production were 1.0 and 8 mL/L for the CSTR and fixed-bed reactor, respectively. Furthermore, an effective method for extracting and purifying vitamin B12 from digested fluid was developed.

Alcohols↗
PubMed2000

Development of a modified three-stage methane production process using food wastes.

A modified three-stage system was developed for the rapid production of methane from food wastes. The primary stage was a semianaerobic hydrolysis/acidogenic system, in which approx 4100 mg/L of volatile fatty acids (VFAs) was produced at a hydraulic retention time (HRT) of 2 d. The operation temperature and pH were 30 degrees C and 5.0-5.5, respectively. The non-degraded materials were removed through a hole at the bottom of the reactor. The secondary stage was an anaerobic acidogenic system equipped with an upflow anaerobic sludge blanket (UASB) type of fermentor. VFA was accumulated up to 6100 mg/L by the addition of Clostridium butyricum to the reactor at an HRT of 2 d. The optimum temperature and pH range were 35 degrees C and 5.0-5.5, respectively. The tertiary methanogenic stage produced CH4 and CO2 from the VFA in the UASB reactor. Methane content was 72% of the total gas volume, and the yield was 0.45-0.50 m3/kg of volatile solids at an HRT of 12 d. The operation temperature and pH were 41 degrees C and 7.6-7.9, respectively. The three-stage process exhibited an unusually high total chemical oxygen demand reduction rate up to 95%. Total nitrogen decreased to 96% and < 10 mg/L of total phosphorus remained in the final effluent.

Aerobiosis↗
PubMed2005

Identification of gas emanated from human skin: methane, ethylene, and ethane.

We investigated whether methane, ethylene and ethane gas can be detected in gas emanating from human skin, which is called skin gas. Skin gas was collected with a homemade stainless-steel trap system, which was cooled with liquid nitrogen, and analyzed with a gas chromatograph fitted with a flame ionization detector (FID). Skin-gas samples were obtained by covering a hand for 30 min with a polyfluorovinyl bag in which pure helium gas was introduced. The bag, the trap system and GC were set up online to avoid any contamination by air. Methane, ethylene and ethane in skin gas were successfully collected at an average amount emanated for 30 min (from ten subjects) of 150 +/- 63, 20 +/- 11 and 17 +/- 8 [mean +/- SD] pg/cm2, respectively.

Adult↗
PubMedDate not supplied

Ammonia, methane, and nitrous oxide emission from pig slurry applied to a pasture in New Zealand.

Much animal manure is being applied to small land areas close to animal confinements, resulting in environmental degradation. This paper reports a study on the emissions of ammonia (NH3), methane (CH4), and nitrous oxide (N2O) from a pasture during a 90-d period after pig slurry application (60 m3 ha-1) to the soil surface. The pig slurry contained 6.1 kg total N m-3, 4.2 kg of total ammoniacal nitrogen (TAN = NH3 + NH4) m-3, and 22.1 kg C m-3, and had a pH of 8.14. Ammonia was lost at a fast rate immediately after slurry application (4.7 kg N ha-1 h-1), when the pH and TAN concentration of the surface soil were high, but the loss rate declined quickly thereafter. Total NH3 losses from the treated pasture were 57 kg N ha-1 (22.5% of the TAN applied). Methane emission was highest (39.6 g C ha-1 h-1) immediately after application, as dissolved CH4 was released from the slurry. Emissions then continued at a low rate for approximately 7 d, presumably due to metabolism of volatile fatty acids in the anaerobic slurry-treated soil. The net CH4 emission was 1052 g C ha-1 (0.08% of the carbon applied). Nitrous oxide emission was low for the first 14 d after slurry application, then showed emission peaks of 7.5 g N ha-1 h-1 on Day 25 and 15.8 g N ha-1 h-1 on Day 67, and decline depending on rainfall and nitrate (NO3) concentrations. Emission finally reached background levels after approximately 90 d. Nitrous oxide emission was 7.6 kg N ha-1 (2.1% of the N applied). It is apparent that of the two major greenhouse gases measured in this study, N2O is by far the more important tropospheric pollutant.

Agriculture↗
PubMedDate not supplied

Application technique and slurry co-fermentation effects on ammonia, nitrous oxide, and methane emissions after spreading: II. Greenhouse gas emissions.

The aim of this study was to investigate the effect of different application techniques on greenhouse gas emission from co-fermented slurry. Ammonia (NH3), nitrous oxide (N2O), and methane (CH4) emissions were measured in two field experiments with four different application techniques on arable and grassland sites. To gather information about fermentation effects, unfermented slurry was also tested, but with trail hose application only. Co-fermented slurry was applied in April at a rate of 30 m3 ha(-1). Measurements were made every 4 h on the first day after application and were continued for 6 wk with gradually decreasing sampling frequency. Methane emissions were <150 g C ha(-1) from co-fermentation products and seemed to result from dissolved CH4. Only in the grassland experiment were emissions from unfermented slurry significantly higher, with wetter weather conditions probably promoting CH4 production. Nitrous oxide emission was significantly increased by injection on arable and grassland sites two- and threefold, respectively. Ammonia emissions were smallest after injection or trail shoe application and are discussed in the preceding paper. We evaluated the climatic relevance of the measured gas emissions from the different application techniques based on the comparison of CO2 equivalents. It was evident that NH3 emission reduction, which can be achieved by injection, is at least compensated by increased N2O emissions. Our results indicate that on arable land, trail hose application with immediate shallow incorporation, and on grassland, trail shoe application, bear the smallest risks of high greenhouse gas emissions when fertilizing with co-fermented slurry.

Ammonia↗
PubMed2006

Enhancing waste decomposition and methane production in simulated landfill using combined anaerobic reactors.

The design of leachate recirculation to enhance municipal solid waste decomposition, methane production and microbial activities was taken into account in this study by using the combined anaerobic reactors of a simulated high organic content landfill reactor and a stabilized fixed film anaerobic reactor. The latter aimed to treat high strength leachate from the simulated landfill reactor before recirculation back to the former reactor. The results showed the possibility to apply this technique to high organic waste landfill where rapid and accumulative acids formed in the leachate were removed and treated by a fixed film anaerobic reactor. In addition, the treated leachate when circulated back to the simulated bioreactor landfill helps accelerate waste decomposition and methane production by providing buffer capacity as well as diluting organic content in the leachate to achieve the favourable conditions for acidogen and methanogen, respectively, to rapidly enter into the methanogenesis phase.

Acids↗
PubMed2003

Genomic markers of ancient anaerobic microbial pathways: sulfate reduction, methanogenesis, and methane oxidation.

Genomic markers for anaerobic microbial processes in marine sediments-sulfate reduction, methanogenesis, and anaerobic methane oxidation-reveal the structure of sulfate-reducing, methanogenic, and methane-oxidizing microbial communities (including uncultured members); they allow inferences about the evolution of these ancient microbial pathways; and they open genomic windows into extreme microbial habitats, such as deep subsurface sediments and hydrothermal vents, that are analogs for the early Earth and for extraterrestrial microbiota.

Bacteria, Anaerobic↗
PubMed1999

Direct measurements of methane emissions from grazing and feedlot cattle.

Methane (CH4) emissions from animals represent a significant contribution to anthropogenically produced radiatively active trace gases. Global and national CH4 budgets currently use predictive models based on emission data from laboratory experiments to estimate the magnitude of the animal source. This paper presents a method for measuring CH4 from animals under undisturbed field conditions and examines the performance of common models used to simulate field conditions. A micrometeorological mass difference technique was developed to measure CH4 production by cattle in pasture and feedlot conditions. Measurements were made continuously under field conditions, semiautomatically for several days, and the technique was virtually nonintrusive. The method permits a relatively large number of cattle to be sampled. Limitations include light winds (less than approximately 2 m/s), rapid wind direction changes, and high-precision CH4 gas concentration measurement. Methane production showed a marked periodicity, with greater emissions during periods of rumination as opposed to grazing. When the cattle were grazed on pasture, they produced .23 kg CH4 x animal(-1) x d(-1), which corresponded to the conversion of 7.7 to 8.4% of gross energy into CH4. When the same cattle were fed a highly digestible, high-grain diet, they produced .07 kg CH4 x animal(-1) x d(-1), corresponding to a conversion of only 1.9 to 2.2% of the feed energy to CH4. These measurements clearly document higher CH4 production (about four times) for cattle receiving low-quality, high-fiber diets than for cattle fed high-grain diets. The mass difference method provides a useful tool for "undisturbed" measurements on the influence of feedstuffs and nutritional management practices on CH4 production from animals and for developing improved management practice for enhanced environmental quality.

Animal Feed↗
PubMed2002

Effect of calf age and dam breed on intake, energy expenditure, and excretion of nitrogen, phosphorus, and methane of beef cows with calves.

The effects of calf age and dam breeds of different milk yield potential on turnover of energy and nutrients were followed in 16 Simmental and 16 Angus beef cows with Angus-sired calves. Calf ages investigated were 1, 4, 7, and 10 mo. The forage offered for ad libitum access consisted of hay for the calves and of a constant mixture of grass silage, meadow hay, and straw (1:0.7:0.3 on a DM basis) for the cows. Calves of 10 mo of age received an additional 2.6 kg DM/d of crushed barley. The animals were kept in groups of four cows and four calves except in the respiration chambers, where only one cow (tethered) and her calf (loose) were grouped together. Indicator techniques were applied to obtain individual data on feces and urine volumes during group housing. In the Simmental cows, heavier on average by 22 kg, voluntary DMI was higher than in the Angus cows (14.0 vs 12.3 kg/d). In calves, DMI from supplementary feeds was 1.6, 3.9, and 6.3 kg/d, on average, at 4, 7, and 10 mo of age, respectively. Dam breed had no significant effect on DMI and ADG of calves and on BW changes of cows. System retention of energy, N, and P showed a curvilinear development with calf age. System energy expenditure, which linearly increased with calf age, was higher with Simmental than with Angus dams (11%), even when adjusted for metabolic BW (8%). Energy loss through methane linearly increased with NDF intake and, consequently, with calf age from 18 to 30 MJ/d (446 to 751 L/d) for cows and calves together. Similarly, fecal and urinary N excretion and fecal P excretion steadily increased with calf age. In calves, the easily volatile N percentage of manure N rapidly decreased from very high levels in young calves. The resulting changes in inclination to gaseous N loss during manure storage for 8 wk were more than compensated by alterations in N intake of the calves, resulting in an increased total system N loss with progressing lactation. Overall, the present results indicate a difference between Angus and Simmental in efficiency of nutrient and energy utilization that might be explained by the difference in amount of delivery of nutrients to the calves via milk vs forage. Suggestions are made as to how the emissions of N, P, and methane, which were excessive in relation to productivity, could be reduced by nutritional means.

Age Factors↗
PubMed1982

Nutritive value of methane fermentation residue in diets fed to feedlot steers.

Nutritive value of the methane fermentation residue (MFR) from the effluent of a large scale thermophilic methane generator was determined in diets fed to feedlot steers. The MFR contained 22.2% dry matter and 21.9% crude protein (dry basis). Two diets containing 10.6% (dry basis) MFR were formulated using the Urea Fermentation Potential (UFP) system such that in one diet N was in excess (-1.6 UFP) while in the other diet energy was in excess (+2.6 UFP). These two diets were compared in a California Net Energy trial with a feedlot diet (-.3 UFP) containing the same ingredients except the MFR. Six steers were fed in a replicated 3(2) Latin square metabolism trial and 70 steers were fed in a 118-d comparative-slaughter, feedlot trial. Digestibilities of dry matter, organic matter, crude protein, acid detergent fiber, ash, total digestible nutrients (TDN) and metabolizable energy were depressed (all P less than .05) in the MFR-containing diets. Steers fed the MFR-containing diets had lower (P less than .05) rates of gain and increased (P less than .05) feed requirements per unit gain. Net energies for maintenance and gain were slightly lower for the MFR-containing diets than the control diet. Crude protein digestibility for the MFR calculated by difference, for the -UFP and the +UFP diets were 37.8 and 50.7%, while corresponding values for TDN were 28.8 and 12.8%, respectively. Concentrations of potentially toxic elements in kidney, liver and muscle as well as flavor and tenderness of steaks were not affected by feeding MFR.

Animals↗
PubMed1999

Effect of the addition of fumarate on methane production by ruminal microorganisms in vitro.

The effect of fumarate used as a feed additive on the reduction of methanogenesis in the rumen was evaluated by in vitro experiments. The addition of fumarate to the culture of mixed ruminal microorganisms that were fermenting hay powder and concentrate reduced methane production. Most fumarate was metabolized to propionate, and a slight increase was noted in other volatile fatty acids. Fumarate was utilized by mixed bacteria but not by mixed protozoa. Fibrobacter succinogenes, Selenomonas ruminantium ssp. ruminantium, Selenomonas ruminantium ssp. lactilytica, Veillonella parvula, and Wollinella succinogenes oxidized H2 by using fumarate as a final electron acceptor, suggesting that these bacteria compete with methanogens for H2, which is the main substrate for methanogenesis in the rumen. However, the affinity of these bacteria to H2 was lower than their affinity to methanogens. These fumarate-utilizing bacteria metabolized malate to products that were similar to those from fumarate, suggesting the possession of fumarate dehydratase. Fibrobacter succinogenes, V. parvula, and W. succinogenes utilized formate, another substrate for methanogenesis, as an electron donor for fumarate reduction. The affinity of these bacteria to formate was higher than the affinity methanogenes have for formate. When methanogens were cocultured with an equal cellular amount of each of the fumarate-utilizing bacteria, methane production was markedly decreased, not only from formate, but also from H2. These results suggest that the addition of fumarate to ruminant feed reduces methanogenesis and enhances propionate production in the rumen.

Adenosine Triphosphate↗
PubMedDate not supplied

[Geochemical characteristics of the carbonate constructions formed during microbial oxidation of methane under anaerobic conditions].

The aragonite constructions of the Black Sea are formed in a stable anaerobic zone and are a perfect object to study the natural mechanism of anaerobic methane oxidation. The most probable pathway of methane oxidation is its methanogen-mediated reaction with bicarbonates, dissolved in seawater, with the formation of water and acetate, which is then consumed by other components of the anaerobic community. Comparison of the delta 13C values of carbonate minerals and organic matter once more demonstrated that the formation of the organic matter of biomass is accompanied by intense fractionation of carbon isotopes, as a result of which the total organic matter of biomass acquires an extremely light isotopic composition, characterized by delta 13C values as low as -83.8@1000.

Acetates↗
PubMedDate not supplied

[Phylogenetic diversity of the archaeal component in microbial mats on coral-like structures associated with methane seeps in the Black Sea].

With the use of molecular ecology methods, the archaea component of microbial mats on coral-like structures associated with methane seeps occurring at a depth of about 200 m in the Black Sea was investigated without the isolation of pure cultures. Using archaea-specific 16S rRNA-targeted oligonucleotide primes, long fragments of genes were amplified, cloned, and sequenced and their phylogenetic analysis was carried out. It was shown that archaea in microbial mats on coral-like structures are represented by two dominant phylotypes that belong to the kingdoms Crenarchaeota and Euryarchaeota and are not specifically related to any described archaea species. The possible role of the revealed archaea in the process of anaerobic methane oxidation is discussed.

Animals↗
PubMedDate not supplied

[Activity of methane-oxidizing bacteria in the adsorbed state].

Adsorption of pure cultures of methane oxidizing bacteria, Methylosinus trichosporium 20 and Methylococcus ucrainicus 21, on glass and coal was studied; the former strain was sorbed on both sorbents, the latter strain was sorbed on coal but not on glass. The rate of methane oxidation by the cells of adsorbed microorganisms was higher than in the case of free cells, and increased with a decrease in dimensions of the sorbent particles.

Adsorption↗
PubMedDate not supplied

[Effect of products of thermophilous methane fermentation on the fermentation of fruit must by Saccharomyces vini].

Experiments were carried out to study the effect of extracts from products of thermophilous methane fermentation at a dose of 0.7+2.0 ml/100 ml on the proliferation and fermentation activity of yeast Saccharomyces vini of the Yablochnaya-7 and Vishnevaya-33 race during their cultivation in the Hansen medium and in the apple and cranberry must with a normal and elevated content of sugar and acid. In some experiments the must was enriched in (NH4)2HPO4 at a dose of 0.3 g/l. Additions of small amounts of products of thermophilous methane fermentation accelerated fermentation of fruit musts with a normal sugar content and to a greater extent musts with an increased sugar content (27%). In the must enriched in (NH4)2HPO4 an almost complete (over 98%) fermentation of sugar developed for 27 days. In the must with an increased acidity (due to citric acid added to bring titrable acidity to 25 g/l) additions of the preparation also accerlerated the begining of the fermentation and increased its intensity.

Fruit↗
PubMed1969

Intestinal hydrogen and methane of men fed space diet.

Intestinal bacteria form two gases, hydrogen (H2) and methane (CH4), that could constitute a fire hazard in a closed chamber. So H2 and CH4 pass from the anus but these gases are also transported by the blood to the lungs and removed to the atmosphere. Several factors affect gas formation: 1) amount and kind of fermentable substrate; 2) abundance, types, and location of microflora; and 3) psychic and somatic conditions that affect the gut. We evaluated the first factor by studying men fed different diets and have also recorded influences of uncontrollable factors. One group of 6 men ate Gemini-type diet (S) and another received a bland formula (F), for 42 days. Breath and rectal gases were analyzed during the first and final weeks. Flatus gases varied widely within dietary groups but much more gas was generated with diet S than with F. In the first 12-hour collection, subjects fed S passed 3 to 209 ml (ATAP) of rectal H2 (avg 52) and 24 to 156 ml (avg 69) from the lungs (assuming normal pulmonary ventilation). With F, these values were 0 to 3 ml (avg 1) and 6 to 36 ml (avg 20). Subjects were calmer during the second test. Gas production was lower with S than initially; F values were unchanged. Methane differed idiosyncratically, presumably due to differences in flora. Computed from 12-hour values, maximum potential daily H2 and CH4 are per man: for S, 730 ml and 382 ml; for F, 80 and 222 ml. Volumes would be larger at reduced spacecraft and suit pressures.

Bacteria↗