Showing papers on "Methanogen published in 1993"

The Biochemistry of archaea (archaebacteria)

Abstract: The archaea - their history and significance, C.R. Woese list of contributors central metabolism of the archaea, M.J. Danson bioenergetics of extreme halophites, V.P. Skulachev biochemistry of methanogenesis, L. Daniels and B. Mukhopadhyay bioenergetics and transport in methanogens and related thermophilic archaea, P. Schonheit signal transduction in halobacteria, D. Oesterhelt and W. Marwan ion transport rhodopsins (bacteriorhodopsin and halorhodopsin) - structure and function, J.K. Lanyi proteins of extreme thermophiles, R. Hensel cell envelopes of archaea - structure and chemistry, O. Kandler and H. Konig membrane lipids of archaea, M. Kates the membrane-bound enzymes of the archaea, L.I. Hochstein chromosome structure, DNA topoisomerases, and DNA polymerases in archaebacteria (archaea), P. Forterre and C. Elie transcription in archaea, W. Zillig et al translation in archaea, R. Amilis et al the structure, function and evolution of archaeal ribosomes, C. Ramirez et al halobacterial genes and genomes, L.C. Schalkwyk structure and function of methanogen genes, J.R. Palmer and J.N. Reeve archaeal hyperthermophile genes, J.Z. Dalgaard and R.A. Garrett epilogue, W.F. Doolittle.

Effects of hydrogen and formate on the degradation of propionate and butyrate in thermophilic granules from an upflow anaerobic sludge blanket reactor.

Abstract: Degradation of propionate and butyrate in whole and disintegrated granules from a thermophilic (55 degrees C) upflow anaerobic sludge blanket reactor fed with acetate, propionate, and butyrate as substrates was examined. The propionate and butyrate degradation rates in whole granules were 1.16 and 4.0 mumol/min/g of volatile solids, respectively, and the rates decreased 35 and 25%, respectively, after disintegration of the granules. The effect of adding different hydrogen-oxidizing bacteria (both sulfate reducers and methanogens), some of which used formate in addition to hydrogen, to disintegrated granules was tested. Addition of either Methanobacterium thermoautotrophicum delta H, a hydrogen-utilizing methanogen that does not use formate, or Methanobacterium sp. strain CB12, a hydrogen- and formate-utilizing methanogen, to disintegrated granules increased the degradation rate of both propionate and butyrate. Furthermore, addition of a thermophilic sulfate-reducing bacterium (a Desulfotomaculum sp. isolated in our laboratory) to disintegrated granules improved the degradation of both substrates even more than the addition of methanogens. By monitoring the hydrogen partial pressure in the cultures, a correlation between the hydrogen partial pressure and the degradation rate of propionate and butyrate was observed, showing a decrease in the degradation rate with increased hydrogen partial pressure. No significant differences in the stimulation of the degradation rates were observed when the disintegrated granules were supplied with methanogens that utilized hydrogen only or hydrogen and formate. This indicated that interspecies formate transfer was not important for stimulation of propionate and butyrate degradation.

Conversion of Methanol and Methylamines to Methane and Carbon Dioxide

Abstract: The first report on methane formation from a methylated one-carbon compound, notably methanol, goes back to 1920 (Groenewegen, 1920). In the thirties, methylotrophic methanogens were systematically studied in the laboratory of Kluy ver and Van Niel (1936). Here, Barker (1936) enriched an organism, then called Methanococcus mazei, which was capable of growth not only on methanol, but also on butanol and acetone. The organism was not pure and the original cultures were lost. Only about 40 years later, the methanogen that met the original description was reisolated and renamed Methanosarcina mazei (Mah, 1980; Mah and Kuhn, 1984). The first methylotroph obtained in axenic culture, and in fact one of the first pure methanogenic species, was isolated by Schnellen (1936), a student of Kluyver. Again, the original cultures of the organism, Methanosarcina barkeri, were lost. M. barkeri has been reisolated as a number of distinct strains from a variety of sources. The type strain, MS, was obtained by Bryant in 1966 (Bryant, 1966; Bryant and Boone, 1987). Biochemically, M. barkeri is the best studied methylotrophic methanogen and most of the work reviewed in this chapter refers to it.

Microbial characteristics of methanogenic sludge consortia developed in thermophilic U ASB reactors

Abstract: The effect of temperature on granulation and microbial interaction of anaerobic sludges grown in thermophilic upflow anaerobic sludge bed (UASB) reactors was investigated at two different temperatures, 55°C (Run 1) and 65°C (Run 2). Each run consisted of two phases. Phase 1 was conducted by feeding acetate for a period of 200 days. In Phase 2, both reactors were fed a mixture of acetate and sucrose for a further 100 days. During Phase 1, no granulation occurred in the sludge of either run. Microscopic observation revealed that the predominant methanogen was Methanothrix in Run 1, whereas Methanobacterium-like bacteria existed to a significant extent in Run 2. The acetate-utilizing methanogenic activity of both sludges increased with increasing test temperature in the range 55–65°C. Since the acetate-grown sludges exhibited far higher H2-utilizing methanogenic activity than acetate-utilizing methanogenic activity, it is suggested that a syntrophic association of acetate-oxidizing bacteria with hydrogenotrophic methanogens was responsible for a considerable portion of the overall acetate elimination in thermophilic anaerobic sludge. During Phase 2, granules coated with either filamentous bacteria or cocci-type bacteria (both presumably acid-forming bacteria) were successfully established in Run 1 and Run 2, respectively. Since the acetate-utilizing methanogenic activities of the granular sludges were four to five times higher than those of the acetate-grown sludges (Phase 1), the co-existence of these “coating bacteria” appeared to contribute to the enclosing of acetate consumers inside granules.

A new polymorphic methanogen, closely related to Methanocorpusculum parvum, living in stable symbiosis within the anaerobic ciliate Trimyema sp.

Abstract: Summary: A new anaerobic microbial consortium has been discovered: the partners are the ciliated protozoon Trimyema sp. and a single species of methanogen. The consortium has been maintained in culture for more than four years. Each ciliate contains up to 300 symbiotic bacteria; many are relatively small and irregularly disc-shaped, and these are distributed throughout the host's cytoplasm, whereas those which are attached to the ciliate's hydrogenosomes are significantly larger and profusely dentate. This attachment is interpreted as an adaptation to maximize capture by the bacteria of the H2 escaping from hydrogenosomes. The 16S rRNA gene of the symbionts has been partially sequenced, and fluorescent oligonucleotide probes have been constructed and used to detect the different morphotypes of the symbiont within the ciliate. The symbionts belong to a new species of archaeobacterium which is a close relative of the free-living methanogen Methanocorpusculum parvum.

Dichloromethane as the sole carbon source for an acetogenic mixed culture and isolation of a fermentative, dichloromethane-degrading bacterium

Abstract: Dichloromethane (DCM) is utilized by the strictly anaerobic, acetogenic mixed culture DM as a sole source of carbon and energy for growth. Growth with DCM was linear, and cell suspensions of the culture degraded DCM with a specific activity of 0.47 mkat/kg of protein. A mass balance of 2 mol of chloride and 0.42 mol of acetate per mol of DCM was observed. The dehalogenation reaction showed similar specific activities under both anaerobic and aerobic conditions. Radioactivity from [14C]DCM in cell suspensions was recovered largely as 14CO2 (58%), [14C]acetate (23%), and [14C]formate (11%), which subsequently disappeared. This suggested that formate is a major intermediate in the pathway from DCM to acetate. Efforts to isolate from culture DM a pure culture capable of anaerobic growth with DCM were unsuccessful, although overall acetogenesis and the partial reactions are thermodynamically favorable. We then isolated bacterial strains DMA, a strictly anaerobic, gram-positive, endospore-forming rod, and DMB, a strictly anaerobic, gram-negative, endospore-forming homoacetogen, from culture DM. Both strain DMB and Methanospirillum hungatei utilized formate as a source of carbon and energy. Coculture of strain DMA with either M. hungatei or strain DMB in solid medium with DCM as the sole added source of carbon and energy was observed. These data support a tentative scheme for the acetogenic fermentation of DCM involving interspecies formate transfer from strain DMA to the acetogenic bacterium DMB or to the methanogen M. hungatei.

Introduction to microbial and thermal methane

Abstract: Commercially, important accumulations of natural gas contain methane formed by two distinctly different processes. Microbial methane, produced biologically by methanogens, makes up roughly 20 percent of all known commercial gas accumulations, whereas thermal methane, generated during the thermochemical alteration of organic matter, accounts for the remaining 80 percent. Microbial and thermal methane can often be distinguished by isotopic and molecular ratios such as [delta][sup 13]C, [delta]D, and methane/(ethane+propane) [C[sub 1]/(C[sub 2]+C[sub 3])]. Microbial methane is produced in strictly anaerobic environments such as numerous aquatic environments, both marine and freshwater. Methanogens exist at surprising depths in the Earth's crust, at temperatures as high as 97[degrees]C. The primary metabolic processes by which methanogens gain energy are fermentation of acetate (CH[sub 3]COO-) and reduction of CO[sub 2]. Other processes can occur depending upon the species of methanogen and the type of available organic matter (such as conversion of formate, methanol, methylamines, and methylated reduced sulfur compounds to methane), but in most cases these processes are not significant ones in nature. CO[sub 2] reduction dominates in marine sediments, whereas acetate fermentation is most common in freshwater sediments. Thermal or thermogenic methane is formed as organic-rich sediments move through progressively higher thermal maturity regimes foundmore » during increasing depths of burial. Thermal methane results from the thermochemical decomposition of organic matter. During early thermal maturation, thermal methane is accompanied by other hydrocarbon and non-hydrocarbon gases and is often associated with crude oil. At the highest thermal maturities, methane alone is formed by cracking of carbon-carbon bonds in kerogen, bitumen, and oils. 18 refs., 5 figs., 2 tabs.« less

Catabolism of Dimethylsulfide and Methane Thiol by Methylotrophic Methanogens

Abstract: We demonstrated the ability of several methylotrophic methanogens to degrade dimethylsulfide and methane thiol to hydrogen sulfide, methane, and carbon dioxide. This is the first report of the growth of a pure culture of methanogen on methane thiol. Methanolobus siciliae HI350, a methylotrophic methanogen isolated from an oil well, was grown routinely on trimethylamine. When this culture was inoculated into a medium with 5 mM dimethyl sulfide, it began producing methane and hydrogen sulfide after a lag of several weeks. Methane production was slow, with an apparent microbial growth rate of 0.0033 h-1 (about 3% as fast as growth on trimethylamine or methanol). The lag was shorter when 2 mM methane thiol was substrate. When a culture of M. siciliae HI350 growing on dimethylsulfide was subcultured on dimethylsulfide, the lag disappeared and growth rate was higher (0.087 h-1). Dimethylsulfide-grown cultures also had no lag when transferred to media with methane thiol. Studies of cell-free extracts suggested that enzymes for the degradation of dimethylsulfide and methane thiol were inducible, whereas those for the degradation of methanol and trimethylamine were constitutive. Degradation of dimethylsulfide or methane thiol was complete, and stoichiometric quantities of methane and hydrogen sulfide were formed. Most surprisingly, this strain could be adapted to grow with high concentrations of dimethylsulfide or methane thiol, as high as 30 mM. Other methanogens which have been reported to catabolize dimethylsulfide are Methanolobus siciliae T4/M, Methanohalophilus zhilinaeae WeN5, Methanohalophilus oregonensis WALL, and strain GS-16. The M. siciliae strains and strain GS-16 were also able to use methane thiol as their catabolic substrate (other strains were not tested). We tested other methylotrophic methanogens for their ability to use dimethylsulfide at concentrations which did not inhibit their ability to degrade trimethylamine and found the following cultures unable to catabolize dimethylsulfide: Methanococcoides methylutens TMA-10, Methanolobus tindarius Tindari 3, Methanolobus vulcani PL-12/M, Methanohalophilus mahii SLP, Methanohalophilus halophilus Z-7982, Methanosarcina mazeii LYC, and Methanosarcina mazeii C 16.

Methanogen Genes and the Molecular Biology of Methane Biosynthesis

Abstract: Methanogenic bacteria (methanogens) produce methane (natural gas; sometimes called biogas) as the end product of their energy-generating metabolism. This biochemical process, termed methanogenesis, is the rate-limiting and final step in the anaerobic biodegradation of organic compounds. It occurs naturally in freshwater and marine sediments, marshes, paddy fields, geothermal springs, and in the digestive tracts of invertebrates and vertebrates. Termites and ruminants are major sources of biologically produced methane. Approximately 65% of the methane released to the atmosphere, equal to approximately 1% of the atmospheric carbon cycle, is of biological origin; the remainder is produced geologically from wells, mines, and natural vents (Ehhalt, 1974; Daniels, 1984).

Isolation of propionate degrading bacterium in co-culture with a methanogen from a cattle dung biogas plant.

Abstract: Various anaerobic hydrolytic and methanogenic bacteria active in cattle dung biogas plants are reported in the literature. Anaerobic bacteria with ability to use volatile fatty acids constitute a vital bridge between hydrolytic bacteria and methanogenic bacteria. The present paper describes the isolation ofSyntrophobacter wolinii a propionate degrading bacterium in co-culture with a hydrogen utilizing methanogenviz.,Methanobacterium formicicum from the fermenting slurry of cattle dung biogas plant. Earlier studies on propionate and butyrate degradation indicatedMethanospirillum hungatei as the hydrogen utilizing partner of the co-culture whereas in the present studies this was not the case. Temperature 35° C, pH 7.5 and 20 mM of propionate were found optimal for growth and activity of co-culture.

Bioenergetic studies of Methanosphaera stadtmanae, an obligate H2–methanol utilising methanogen

Abstract: In Methanosphaera stadtmanae producing methane from the reduction of methanol with H2, sodium (> 0.3 mM Na+) was not required for methanogenesis or ATP synthesis. The ATPase inhibitor N,N′-dicycloh...

Reaction method for immobilized microorganism

Abstract: PURPOSE:To accomplish treatment with immobilized microorganisms economically in high efficiency by contact with a reactive substrate of such immobilized microorganisms obtained by dehydrating at a specified temperature microorganisms either cultured or collected from the natural world followed by drying CONSTITUTION:Microorganisms selected from bacteria representing aerobic microorganism treatment sludge such as activated sludge (eg Aerobacter), acidic bacteria representing anaerobic bacteria treatment sludge such as for methane fermentation, and methanogen (methane bacteria), are dehydrated at <=70 degC and dried in a solid form to obtain immobilized microbial cells with a water content of <=85wt% Thence, the microbial cells are cut or ground to uniformize granular size into immobilized microorganisms 1-5mm in granular diameter A reactor is then packed with the microorganisms at a specified packing rate followed by introducing a reactive substrate such as synthetic effluent into the reactor to effect reaction while feeding air to treat the effluent, thus giving desired treated water

Application of analytical microbial ecology to the anaerobic conversion of biomass to methane.

Abstract: Lipid biomarker and radiotracer analysis, microcosms, and the inhibitors oxygen and chloroform were used to monitor the operation of a unique design of high-solids high-productivity methanogenic reactor. The 2 reactors examined gave an example of a microbial community adapted to the batch feeding schedule and very high methane production. The second reactor had been damaged by overfeeding. It had adapted to high acetate and ammonia concentrations, low pH and productivity. Under oxygen inhibition, methanogens were out-competed by facultative anaerobes, rather than killed. While chloroform inhibition abolished radiolabeled acetate incorporation into methane, label was incorporated into archaeal ether lipids, possibly indicating an unknown methanogen adaptation to toxic stress. The utility of analytical microbial ecology to practical problems is discussed.

Anaerobic treatment of organic waste water containing sulfate ion

Abstract: PURPOSE:To anaerobically treat an org. waste water contg. sulfate ion while maintaining high BOD load and BOD removing rate by methane fermentation. CONSTITUTION:An org. waste water contg. sulfate ion is anaerobically treated by methane fermentation in a treating tank 1. The gas generated from the tank is desulfurized in a desulfurization tank 8 and introduced continuously and quantitatively into a liq. in the treating tank through a diffuser 10 and circulated, and the hydrogen sulfide concn. in the gas is decreased below 10,000ppm. Consequently, the concn. of the hydrogen sulfide deteriorating the activity of methanogen is lowered above 70mg/L, and high BOD load and BOD removing rate are simultaneously maintained.