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  • 1
    Electronic Resource
    Electronic Resource
    One carbon metabolism in methanogenic bacteria (1978)
    Springer
    Archives of microbiology 119 (1978), S. 49-57 
    Details
    ISSN: 1432-072X
    Keywords: C1 metabolism ; Methanogenesis ; Methylotrophy ; Methanosarcina Chemolithotrophy ; Autotrophy ; Growth yields ; Dehydrogenase ; Archaebacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two strains of Methanosarcina (M. Barkeri strain MS, isolated from sewage sludge, and strain UBS, isolated from lake sediments) were found to have similar cellular properties and to have DNA base compositions of 44 mol percent guanosine plus cytosine. Strain MS was selected for further studies of its one-carbon metabolism. M. barkeri grew autotrophically via H2 oxidation/CO2 reduction. The optimum temperature for growth and methanogenesis was 37°C. H2 oxidation proceeded via an F420-dependent NADP+-linked hydrogenase. A maximum specific activity of hydrogenase in cell-free extracts, using methyl viologen as electron acceptor, was 6.0 μmol min · mg protein at 37°C and the optimum pH (9.0). M. barkeri also fermented methanol andmethylamine as sole energy sources for growth. Cell yields during growth on H2/CO2 and on methanol were 6.4 and 7.2 mg cell dry weight per mmol CH4 formed, respectively. During mixotrophic growth on H2/CO2 plus methanol, most methane was derived from methanol rather than from CO2. Similar activities of hydrogenase were observed in cell-free extracts from H2/CO2-grown and methanol-grown cells. Methanol oxidation apparently proceeded via carrierbound intermediates, as no methylotrophy-type of methanol dehydrogenase activity was observed in cell-free extracts. During growth on methanol/CO2, up to 48% of the cell carbon was derived from methanol indicating that equivalent amounts of cell carbon were derived from CO2 and from an organic intermediate more reduced than CO2. Cell-free extracts lacked activity for key cell carbon synthesis enzymes of the Calvin cycle, serine path, or hexulose path.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00407927
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  • 2
    Electronic Resource
    Electronic Resource
    Metabolic regulation of carbon and electron flow as a function of pH during growth of Sarcina ventriculi (1991)
    Springer
    Archives of microbiology 155 (1991), S. 325-329 
    Details
    ISSN: 1432-072X
    Keywords: Anaerobic acidophile ; pH Adaptation ; Sarcina ventriculi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The physiology and biochemistry of Sarcina ventriculi was studied in order to determine adaptations made by the organism to changes in environmental pH. The organism altered carbon and electron flow from acetate, formate and ethanol production at neutral pH, to predominantly ethanol production at pH 3.0. Increased levels of pyruvate dehydrogenase (relative to pyruvate decarboxylase) and acetaldehyde dehydrogenase occurred when the organism was grown at neutral pH, indicating the predominance of carbon flux through the oxidative branch of the pathway for pyruvate metabolism. When the organism was grown at acid pH, there was a significant increase in pyruvate decarboxylase levels and a decrease in acetaldehyde dehydrogenase, causing flux through the non-oxidative branch of the pathway. CO2 reductase and formate dehydrogenase were not regulated as a function of growth pH. Pyruvate dehydrogenase possessed Michaelis-Menten kinetics for pyruvate with an apparent K m of 2.5 mM, whereas pyruvate decarboxylase exhibited sigmoidal kinetics, with a S0.5 of 12.0 mM. Differences in total protein banding patterns from cells grown at pH extremes suggested that synthesis of pyruvate decarboxylase and other enzymes was in part responsible for metabolic regulation of the fermentation products formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00243450
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  • 3
    Electronic Resource
    Electronic Resource
    Purification and characterization of membrane-bound hydrogenase from Methanosarcina barkeri MS (1994)
    Springer
    Archives of microbiology 161 (1994), S. 47-54 
    Details
    ISSN: 1432-072X
    Keywords: Key words:Methanosarcina barkeri– Hydrogenase – Membrane bound – F420 nonreactive – Cytochrome b– Hydrogen uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Hydrogenase was solubilized from the membrane of acetate-grown Methanosarcina barkeri MS and purification was carried out under aerobic conditions. The enzyme was reactivated under reducing conditions in the presence of H2. The enzyme showed a maximal activity of 120±40 µmol H2 oxidized ⋅ min−1 ⋅ mg−1 with methyl viologen as an electron acceptor, a maximal hydrogen production rate of 45±4 µmol H2 ⋅ min−1×mg−1 with methyl viologen as electron donor, and an apparent K m for hydrogen oxidation of 5.6±1.7 µM. The molecular weight estimated by gel filtration was 98,000. SDS-PAGE showed the enzyme to consist of two polypeptides of 57,000 and 35,000 present in a 1:1 ratio. The native protein contained 8±2 mol Fe, 8±2 mol S2−, and 0.5 mol Ni/mol enzyme. Cytochrome b was reduced by hydrogen in a solubilized membrane preparation. The hydrogenase did not couple with autologous F420 or ferredoxin, nor with FAD, FMN, or NAD(P)+. The physiological function of the membrane-bound hydrogenase in hydrogen consumption is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248892
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  • 4
    Electronic Resource
    Electronic Resource
    Cellulolytic and physiological properties of Clostridium thermocellum (1977)
    Springer
    Archives of microbiology 114 (1977), S. 1-7 
    Details
    ISSN: 1432-072X
    Keywords: Thermophilic ; Anaerobic cellulolytic bacteria ; Clostridium thermocellum ; Cellular growth properties ; Cellulose degradation ; Cellulase (exoglucanase and endoglucanase) production ; Cellulase properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three strains of Clostridium thermocellum obtained from various sources were found to have nearly identical deoxyribonucleic acid guanosine plus cytosine contents that ranged from 38.1–39.5 mole-%. All strain examined fermented only cellulose and cellulose derivatives, but not glucose, or xylose or other sugars. The principal cellulose fermentation products were ethanol, lactate, acetate, hydrogen and carbon dioxide. Growth of C. thermocellum on cellulose resulted in the production of extracellular cellulase that was non-oxygen labile, was thermally stable at 70° C for 45 min and adsorbed strongly on cellulose. Production of cellulase during fermentation correlated linearly with growth and cellulose degradation. Both the yield and specific activity of crude cellulase varied considerably with the specific growth substrates. Highest cellulase yield was obtained when grown on native cellulose, α-cellulose and low degree of polymerization cellulose but not carboxymethylcellulose or other carbohydrate sources. Cellulase activity was not detected when cells were grown on cellobiose. Crude extracellular protein preparations lacked proteolytic and cellobiase activity. The pH and temperafure optima for endoglucanase activity were 5.2 and 65° C, respectively, while that of the exoglucanase activity were 5.4 and 64° C, respectively. The specific activity at 60° c for exoglucanase and endoglucanase of crude cellulase obtained from cells grown on cellulose (MN 300) was 3.6 μmoles reducing sugar equivalents released per h (unit)/mg of protein and 1.5 μmole reducing sugar equivalent released per min (unit)/mg of protein, respectively. The yield of endoglucanase was 125 units per g of cellulose MN 300 degraded and that of exoglucanase was 300 units per g of cellulose MN 300 degraded. Glucose and cellobiose were the hydrolytic end products of crude cellulase action on cellulose, cellotraose and cellotriose in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429622
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  • 5
    Electronic Resource
    Electronic Resource
    Acetate metabolism inMethanosarcina barkeri (1978)
    Springer
    Archives of microbiology 119 (1978), S. 175-182 
    Details
    ISSN: 1432-072X
    Keywords: Methanogenesis ; Methylotrophy ; Methanosarcina ; Archaebacteria ; Acetate ; Anaerobes ; Methanogens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methanosarcina barkeri was grown by acetate fermentation in complex medium (N2 gas phase). The molar growth yield was 1.6–1.9 g cells/mol methane formed. Under these conditions 63–82% of the methane produced byMethanosarcina strains was derived from the methyl carbon of acetate, indicating that some methane was derived from other media components. Growth was not demonstrated in complex media lacking acetate or mineral acetate medium containing acetate but lacking H2/CO2, methanol, or trypticase and yeast extract. Acetate metabolism byM. barkeri strain MS was further exmined in mineral acetate medium containing H2/CO2 and/or methanol, but lacking cysteine. Under these conditions, more methane was derived from the methyl carbon of acetate than from the carboxyl carbon. Methanogenesis from the methyl group increased with increasing acetate concentration. The methyl carbon contributed up to 42% of the methane formed with H2/CO2 and up to 5% with methanol. Methanol stimulated the oxidation of the methyl group of acetate to CO2. The average rates of methane formation from acetate were 1.3 nomol/min ·ml/culture (0.04mg2 cell dry weight) in defined media (gas phase H2/CO2) and complex media (gas phase N2). Acetate contributed up to 60% of cell carbon formed under the growth conditions examined. Similar quantities of cell carbon were derived from the methyl and carboxyl carbons of acetate, suggesting incorporation of this compound as a two-carbon unit. Incorporated acetate was not preferentially localized in lipid material, as 70% of the incorporated acetate was found in the wall and protein cell fractions. Acetate catabolism was stimulated by pregrowing of cultures in media containing acetate, while acetate anabolism was not influenced. The results are discussed in terms of the differences between the mechanisms of acetate catabolism and anabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964270
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  • 6
    Electronic Resource
    Electronic Resource
    Thermoanaerobium brockii gen. nov. and sp. nov., a new chemoorganotrophic, caldoactive, anaerobic bacterium (1979)
    Springer
    Archives of microbiology 122 (1979), S. 41-48 
    Details
    ISSN: 1432-072X
    Keywords: Thermoanaerobium brockii ; Genus, Species description ; Obligate anaerobe ; Sugar and starch fermentation ; Ethanol production ; Lactic acid ; Thermophile ecology and physiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The isolation of a new anaerobic thermophilic bacterium, Thermoanaerobium brockii, from volcanic features is described. Successful enrichment required a complex medium containing glucose or other fermentable sugars and incubation temperatures of 55–80° C. Strains of T. brockii were gram positive, rods of uneven length that existed singly, in pairs, chains or filaments. Electron micrographs of thin sections of cell revealed a monolayered cell wall and a constrictive or “pinching off” cell division process. The organism was nonsporeforming, obligately anaerobic and chemoorganotrophic. The optimal temperature for growth was 65–70° C, the maxium was below 85° C and the minimum above 35° C. The doubling time at the optimal temperature for growth was about 1 h. The DNA base composition of three strains of T. brockii varied from 30.0–31.4 mol % guanosine plus cytosine. Fermentable carbohydrates included glucose, sucrose, maltose, lactose, cellobiose and insoluble starch. The fermentation products of cells grown on glucose were ethanol, lactic acid, acetic acid, hydrogen and carbon dioxide. Growth of all strains tested was inhibited by fairly low concentrations of cycloserine, penicillin, streptomycin, tetracycline and chloramphenicol. The possible ecological, evolutionary, and industrial significance, and taxonomic relationships of Thermoanaerobium are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408044
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  • 7
    Electronic Resource
    Electronic Resource
    Bacterial methanogenesis: Acetate as a methane precursor in pure culture (1975)
    Springer
    Archives of microbiology 104 (1975), S. 129-134 
    Details
    ISSN: 1432-072X
    Keywords: Methane Bacteria ; Methanosarcina barkeri ; Methanobacterium thermoautotrophicum ; Substrates for Methanogenesis ; Acetate Utilization ; Chemolithotrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pure cultures of methanogenic bacteria were shown to utilize acetate as a methanogenic substrate. In the presence of hydrogen, both Methanosarcina barkeri and Methanobacterium thermoautotrophicum rapidly converted acetate to methane. This reaction was shown to be dependent on the concentration of hydrogen and acetate. In the absence of hydrogen, acetate was not fermented by methane bacteria. Both the methyl and carboxyl position of acetate were reduced to methane. More 14C-methane was detected from methyl than carboxyl-labeled acetate. The utilization of acetate by cultures of M. thermoautotrophicum was enhanced by addition of CO2/HCO3 −. Methyl labeled acetate was shown to be incorporated into whole cells and converted to 14CO2 and 14CH4 in the presence of H2 and 25 mM CO2/HCO3 −. The importance of acetate utilization in microbial methanogenesis was discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00447312
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  • 8
    Electronic Resource
    Electronic Resource
    Isolation of auxotrophic mutants in support of ammonia assimilation via glutamine synthetase in Methanobacterium ivanovii (1986)
    Springer
    Archives of microbiology 144 (1986), S. 350-354 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium ; Ammonia assimilation enzymes ; GS-GOGAT pathway ; NH + 4 regulation ; M. ivanovii glutamine auxotrophs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Various enzymes involved in the initial metabolic pathway for ammonia assimilation by Methanobacterium ivanovii were examined. M. ivanovii showed significant activity of glutamine synthetase (GS). Glutamate synthase (GOGAT) and alanine dehydrogenase (ADH) were present, wheras, glutamate dehydrogenase (GDH) was not detected. When M. ivanovii was grown with different levels of NH + 4 (i.e. 2, 20 or 200 mM), GS, GOGAT and ADH activities varied in response to NH + 4 concentration. ADH was not detected at 2 mM level, but its activity increased with increased levels of NH + 4 in the medium. Both GS and GOGAT activities increased with decreasing concentrations of NH + 4 and were maximum when ammonia was limiting, suggesting that at low NH + 4 levels, GS and GOGAT are responsible for ammonia assimilation and at higher NH + 4 levels, ADH might play a role. Metabolic mutants of M. ivanovii that were auxotrophic for glutamine were obtained and analyzed for GS activity. Results indicate two categories of mutants: i) GS-deficient auxotrophic mutants and ii) GS-impaired auxotrophic mutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409884
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  • 9
    Electronic Resource
    Electronic Resource
    Regulation and function of ferredoxin-linked versus cytochrome b-linked hydrogenase in electron transfer and energy metabolism of Methanosarcina barkeri MS (1994)
    Springer
    Archives of microbiology 162 (1994), S. 26-32 
    Details
    ISSN: 1432-072X
    Keywords: Key words     Methanosarcina barkeri ; Hydrogenase ; Regulation ; ATP synthesis ; Ferredoxin ; F420
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract      Acetate-grown cells of Methanosarcina barkeri MS were found to form methane from H2 : CO2 at the same rate as hydrogen-grown cells. Cells grown on acetate had similar levels of soluble F420-reactive hydrogenase I, and higher levels of cytochrome-linked hydrogenase II compared to hydrogen-grown cells. The hydrogenase I and II activities in the crude extract of acetate-grown cells were separated by differential binding properties to an immobilized Cu2+ column. Hydrogenase II did not react with ferredoxin or F420, whereas hydrogenase I coupled to both ferredoxin and F420. A reconstituted soluble protein system composed of purified CO dehydrogenase, F420-reactive hydrogenase I fraction, and ferredoxin produced H2 from CO oxidation at a rate of 2.5 nmol/ min · mg protein. Membrane-bound hydrogenase II coupled H2 consumption to the reduction of CoM-S-S-HTP and the synthesis of ATP. The differential function of hydrogenase I and II is ascribed to ferredoxin-linked hydrogen production from CO and cytochrome b-linked H2 consumption coupled to methanogenesis and ATP synthesis, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050097
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  • 10
    Electronic Resource
    Electronic Resource
    Influence of culture parameters on lignin metabolism byPhanerochaete chrysosporium (1978)
    Springer
    Archives of microbiology 117 (1978), S. 277-285 
    Details
    ISSN: 1432-072X
    Keywords: White-rot fungi ; Nutrient nitrogen metabolism ; Fungus physiology ; Mycelial pellets ; pH ; Growth substrate ; Wood decay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Culture parameters influencing metabolism of synthetic14C-lignins to14CO2 in defined media have been studied in shallow batch cultures of the ligninolytic wood-destroying HymenomycetePhanerochaete chrysosporium Burds. Study of the effect of O2 concentration in the gas phase above non-agitated cultures indicated essentially complete absence of attack on the lignin polymer at 5% O2 in N2, and a 2- to 3-fold enhancement by 100% O2 as compared to air (21% O2). Agitation of the cultures resulting in the formation of mycelial pellets greatly suppressed lignin decomposition. The optimum culture pH for lignin decomposition was 4 to 4.5, with marked suppression above 5.5 and below 3.5. The source of nutrient nitrogen (NO 3 − , NH 4 + , amino acids) had little influence on lignin decomposition, but the concentration of nitrogen was critical; decomposition at 24 mM was only 25–35% of that at 2.4 mM N. Thiamine was the only vitamin required for growth and lignin decomposition. Under the optimum conditions developed, decomposition of 5 mg of synthetic lignin was accompanied by utilization of approximately 100 mg of glucose. The influence of the various culture parameters was analogous for metabolism of synthetic lignin labeled in the ring-,side chain-, and methoxyl carbon atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00738547
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