Showing papers on "Methanosarcina barkeri published in 1981"

Anaerobic Degradation of Lactate by Syntrophic Associations of Methanosarcina barkeri and Desulfovibrio Species and Effect of H(2) on Acetate Degradation.

Abstract: When grown in the absence of added sulfate, cocultures of Desulfovibrio desulfuricans or Desulfovibrio vulgaris with Methanobrevibacter smithii (Methanobacterium ruminantium), which uses H2 and CO2 for methanogenesis, degraded lactate, with the production of acetate and CH4. When D. desulfuricans or D. vulgaris was grown in the absence of added sulfate in coculture with Methanosarcina barkeri (type strain), which uses both H2-CO2 and acetate for methanogenesis, lactate was stoichiometrically degraded to CH4 and presumably to CO2. During the first 12 days of incubation of the D. desulfuricans-M. barkeri coculture, lactate was completely degraded, with almost stoichiometric production of acetate and CH4. Later, acetate was degraded to CH4 and presumably to CO2. In experiments in which 20 mM acetate and 0 to 20 mM lactate were added to D. desulfuricans-M. barkeri cocultures, no detectable degradation of acetate occurred until the lactate was catabolized. The ultimate rate of acetate utilization for methanogenesis was greater for those cocultures receiving the highest levels of lactate. A small amount of H2 was detected in cocultures which contained D. desulfuricans and M. barkeri until after all lactate was degraded. The addition of H2, but not of lactate, to the growth medium inhibited acetate degradation by pure cultures of M. barkeri. Pure cultures of M. barkeri produced CH4 from acetate at a rate equivalent to that observed for cocultures containing M. barkeri. Inocula of M. barkeri grown with H2-CO2 as the methanogenic substrate produced CH4 from acetate at a rate equivalent to that observed for acetate-grown inocula when grown in a rumen fluid-vitamin-based medium but not when grown in a yeast extract-based medium. The results suggest that H2 produced by the Desulfovibrio species during growth with lactate inhibited acetate degradation by M. barkeri.

Nickel requirement and factor F430 content of methanogenic bacteria.

Abstract: Methanobacterium thermoautotrophicum has been reported to require nickel for growth and to contain high concentrations of a nickel tetrapyrrole designated factor F430. In this communication it is shown that all methanogenic bacteria investigated incorporated nickel during growth and also synthesized factor F430. This was also true for Methanobrevibacter smithii, which is dependent on acetate as a carbon source, and for Methanosarcina barkeri growing on acetate or methanol as energy sources. Other bacteria, including Acetobacterium woodii and Clostridium thermoaceticum, contained no factor F430. It is further shown that two yellow nickel-containing degradation products were formed from factor F430 when heated at pH 7. This finding explains why several forms of factor F430 were found in methanogenic bacteria when a heat step was employed in the purification procedure.

Influence of corrinoid antagonists on methanogen metabolism

Abstract: Iodopropane inhibited cell growth and methane production when Methanobacterium thermoautotrophicum, Methanobacterium formicicum, and Methanosarcina barkeri were cultured on H2-CO2. Iodopropane (40 microM) inhibited methanogenesis (30%) and growth (80%) when M. barkeri was cultured mixotrophically on H2-CO2-methanol. The addition of acetate to the medium prevented the observed iodopropane-dependent inhibition of growth. The concentrations of iodopropane that caused 50% inhibition of growth of M. barkeri on either H2-CO2, H2-CO2-methanol, methanol, and acetate were 112 +/- 6, 24 +/- 2, 63 +/- 11, and 4 +/- 1 microM, respectively. Acetate prevented the iodopropane-dependent inhibition of one-carbon metabolism. Cultivation of M. barkeri on H2-CO2-methanol in bright light also inhibited growth and methanogenesis to a greater extent in the absence than in the presence of acetate in the medium. Acetate was the only organic compound examined that prevented iodopropane-dependent inhibition of one-carbon metabolism in M. barkeri. The effect of iodopropane and acetate on the metabolic fates of methanol and carbon dioxide was determined with 14C tracers when M. barkeri was grown mixotrophically on H2-CO2-methanol. The addition of iodopropane decreased the contribution of methanol to methane and cell carbon while increasing the contribution of CO2 to cell carbon. Regardless of iodopropane, acetate addition decreased the contribution of methanol and CO2 to cell carbon without decreasing their contribution to methane. The corrinoid antagonists, light and iodopropane, appeared most specific for methanogen metabolic reactions involved in acetate synthesis from one-carbon compounds and acetate catabolism.

Influence of sulphur-containing compounds on the growth of Methanosarcina barkeri in a defined medium

Abstract: Optimal growth of Methanosarcina barkeri occurred in a defined medium containing methanol when 2.5–4 mM sodium sulphide was added giving a concentration of 0.04–0.06 mM dissolved sulphide (HS−+S2−. When the sulphide concentration was too low for optimal growth (e.g., 0.1 mM Na2S added) the addition of the redox resin ‘Serdoxit’ acted as a sulphide reservoir and caused a significant stimulation of growth. Furthermore it could be demonstrated that iron sulphide, zinc sulphide or L-methionine could also act as sulphur sources while the addition of sodium sulphate to sulphide-depleted media failed to restore growth. The amino acid L-cysteine (0.85 mM) stimulated growth but could not replace Na2S.

The Methanogenic Bacteria

Abstract: The methanogenic bacteria are unique among pro-karyotes because they produce a hydrocarbon, methane, as a major product of anaerobic metabolism. This physiological property was proposed in 1956 by H. A. Barker as the main taxonomic characteristic of a morphologically diverse group of bacteria which he termed the Methanobacteriaceae. The taxonomy of this physiological family has been obfuscated by the difficulty of obtaining members in pure culture. Consequently, various species were named on the basis of the types of substrates converted to methane by “purified” (i.e., enrichment) cultures containing a predominant morphological type suspected of methanogenesis. Only three species, Methanobacterium formicicum, Methano-coccus vannielii, and Methanosarcina barkeri, were isolated in axenic culture by the time of Barker’s review of these organisms (Barker, 1956).

Effect of trace elements and vitamins on the growth of Methanosarcina barkeri

Abstract: Growth of Methanosarcina barkeri on methanol as energy source was found to be dependent on cobalt and molybdenum. In the presence of 10−6 M Co and 5 × 10−7M Mo optimal growth occurred. Furthermore it could be demonstrated that nickel and selenium each in a concentration of 10−7 M stimulated the growth of this methanogenic bacterium while the following elements tested in the range of 10−7 M to 10−3 had no influence: B, Cr, Cu, Mn, Pb. The requirement of Co and Ni for optimal growth are in accordance with the results that the cells contain the Co containing corrinoid Factor III (0.1 – 0.2 mg 5-hydroxylbenzimidazolylcyanocobamide per g wet cells) and Factor F430, a nickel component. Studies on the vitamin dependency of M. barkeri showed that this strain needs only the vitamin riboflavin for the growth in a defined medium. Under these conditions a cell density of 2.6 g dry cells/l could be obtained in a fed batch culture.

Coenzyme M derivatives and their effects on methane formation from carbon dioxide and methanol by cell extracts of Methanosarcina barkeri.

Abstract: Extracts of Methanosarcina barkeri reduced methanol and CO2 to CH4 in the presence of H2 and converted methanol stoichiometrically into CH4 and CO2 in the absence of H2. In dialyzed cell-free extracts these reactions were stimulated by 2-mercaptoethanesulfonic acid (coenzyme M) and some derivatives (acetyl and formylcoenzyme M and the oxidized form of coenzyme M), which could be converted to coenzyme M by enzyme systems present in the extracts. Methylcoenzyme M could not be used in these systems.

Conversion of Cellulose to Methane and Carbon Dioxide by Triculture of Acetivibrio cellulolyticus, Desulfovibrio sp., and Methanosarcina barkeri.

Abstract: The fermentation of cellulose by monocultures of Acetivibrio cellulolyticus and cocultures of A. cellulolyticus-Methanosarcina barkeri, A. cellulolyticus-Desulfovibrio sp., and A. cellulolyticus-M. barkeri-Desulfovibrio sp. was studied. The monoculture produced ethanol, acetate, H(2), and CO(2). More acetate and less ethanol was formed by the cocultures than by the monoculture. Acetate was utilized by M. barkeri in coculture with A. cellulolyticus after a lag period, whereas ethanol was metabolized by the sulfate reducer only under conditions of low H(2) partial pressure, i.e., when cocultured with A. celluloyticus-M. barkeri or when grown together with the methanogen. Only the three-component culture carried out the rapid conversion of cellulose to CO(2) and methane. Furthermore, this culture hydrolyzed the most cellulose-85% of that initially present. This amount was increased to 90% by increasing the population of M. barkeri in the triculture. Methane production was also increased, and a quicker fermentation rate was achieved.

Immobilization of the methanogenic bacterium Methanosarcina barkeri

Abstract: Whole cells of the methanogen Methanosarcina barkeri were immobilized in an alginate network which was crosslinked with Ca2+ ions. The rates of methanol conversion to methane of entrapped cells were found to be in the same range as the corresponding rates of free cells. Furthermore, immobilized cells were active for a longer period than free cells. The particle size of the spherical alginate beads (1.2 mm-3.7 mm ϕ) and thus diffusion had no obvious influence on the turnover of methanol. The half-value period for methanol conversion activity determined in a buffer medium was approximately 4 days at 37°C for entrapped cells. The apparent Km value K for such cells was nearly 140mM and the Vmax value was about 1.2 μmol methanol/min/mg entrapped protein. Therefore the high rates of methanol degradation measured, e.g., 0.5 μmol methanol/min/mg entrapped protein, indicated that the immobilization technique preserved the cellular functions of this methanogenic bacterium.

Levels of coenzyme F420, coenzyme M, hydrogenase, and methylcoenzyme M methylreductase in acetate-grown Methanosarcina

Abstract: Methanosarcina barkeri strain 227 maintained on an acetate medium for 2 years was found to possess hydrogenase, methylcoenzyme M methylreductase, coenzyme F420, and coenzyme M. The levels of these constituents in acetate-grown cells were similar to those found in cells of the same strain grown on methanol or hydrogen and carbon dioxide.

Formation of trideuteromethane from deuterated trimethylamine or methylamine by Methanosarcina barkeri.

Abstract: Methanosarcina barkeri was grown on trimethylamine, methylamine, or methanol containing completely deuterated methyl groups. Methane was collected and analyzed in a mass spectrometer. It contained 79 to 83% CD3H and 14 to 18% CD2H2. This demonstrated that the methyl groups of the above compounds served primarily as direct precursors of methane.

Uni- and Dicarbon Metabolism of Methanosarcina Barkeri Strain Ms in Defined Medium

Abstract: The contributions of C-2 and C-1 labelled acetate to CH4 and CO2 were examined in acetate adapted culture of Methanosarcina barkeri grown in mineral medium The methyl group of acetate accounted for the majority of CH4 produced; however, 15% of the C-2 of acetate was oxidized to 14CO2 This oxidation correlated with the concurrent reduction of the carboxyl group 14CH4 was produced from 14C-1 acetate in amounts slightly less than the values detected for 14C-2 acetate conversion to CO2 Acetate adapted cells were capable of simultaneous metabolism of both methanol and acetate during growth in a medium that contained 50 mM of each substrate The rate of 14CH4 generation from 14C-2 acetate was logrithmic and faster than that observed during unitrophic growth on acetate The rate of 14CO2 production from 14C-2 acetate was twice that of unitrophic cultures After methanol depletion the rate of 14CH4 production remained unchanged, while 14CO2 production decreased two-fold In mixotrophic growth studies with 120 mM methanol and 50 mM acetate the rate of 14CH2 production from 14C-2 acetate decreased several fold over that observed in unitrophic or in the equal (substrate) mixotrophic cultures However, μ CH4 decreased 2-fold which suggests that methanol toxcity was the cause of this effect