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At least 19 recordsLinked to original sources
PubMed2000

Cultivation and in situ detection of a thermophilic bacterium capable of oxidizing propionate in syntrophic association with hydrogenotrophic methanogens in a thermophilic methanogenic granular sludge.

The thermophilic, anaerobic, propionate-oxidizing bacterial populations present in the methanogenic granular sludge in a thermophilic (55 degrees C) upflow anaerobic sludge blanket reactor were studied by cultivation and in situ hybridization analysis. For isolation of propionate-degrading microbes, primary enrichment was made with propionate as the sole energy source at 55 degrees C. After several attempts to purify the microbes, a thermophilic, syntrophic, propionate-oxidizing bacterium, designated strain SI, was isolated in both pure culture and coculture with Methanobacterium thermoautotrophicum. Under thermophilic (55 degrees C) conditions, strain SI oxidized propionate, ethanol, and lactate in coculture with M. thermoautotrophicum. In pure culture, the isolate was found to ferment pyruvate. 16S ribosomal DNA sequence analysis revealed that the strain was relatively close to members of the genus Desulfotomaculum, but it was only distantly related to any known species. To elucidate the abundance and spatial distribution of organisms of the strain SI type within the sludge granules, a 16S rRNA-targeted oligonucleotide probe specific for strain SI was developed and applied to thin sections of the granules. Fluorescence in situ hybridization combined with confocal laser scanning microscopy revealed that a number of rod-shaped cells were present in the middle and inner layers of the thermophilic granule sections and that they formed close associations with hydrogenotrophic methanogens. They accounted for approximately 1.1% of the total cells in the sludge. These results demonstrated that strain SI was one of the significant populations in the granular sludge and that it was responsible for propionate oxidation in the methanogenic granular sludge in the reactor.

Bacteria↗
PubMed1995

Sulfate reduction by a syntrophic propionate-oxidizing bacterium.

The syntrophic propionate-oxidizing bacterium MPOB was able to grow in the absence of methanogens by coupling the oxidation of propionate to the reduction of sulfate. Growth on propionate plus sulfate was very slow (mu = 0.024 day-1). An average growth yield was found of 1.5 g (dry weight) per mol of propionate. MPOB grew even slower than other sulfate-reducing syntrophic propionate-oxidizing bacteria. The growth rates and yields of strict sulfate-reducing bacteria (Desulfobulbus sp.) grown on propionate plus sulfate are considerably higher.

Acetates↗
PubMed1990

In vivo propionate oxidation as a prognostic indicator in disorders of propionate metabolism.

Biochemical markers such as plasma and urinary metabolite concentrations and in vitro enzyme activity are of limited prognostic value in the most common disorders of propionate metabolism, methylmalonic acidaemia (MMA) and propionic acidaemia (PA). In vivo propionate oxidation was compared with conventional prognostic measures as predictors of clinical severity in seven children with MMA and six with PA. Propionate oxidation was measured using a continuous infusion of [1-13C]propionate and was expressed as the rate of appearance of 13CO2 as a percentage of the propionate infusion rate. Children with MMA (mean oxidation 51.2%, range 17.5-91.6, P less than 0.05) and with PA (mean oxidation 36.3%, range 3.0-91.1, P = NS) oxidised substantially less propionate than controls (mean oxidation 81.9%, range 69.4-101.0, n = 5). Percentage oxidation was a better predictor of the clinical severity score (r = 0.75, P less than 0.01) than was in vitro enzyme activity, plasma propionate or methylmalonate concentration or urinary metabolite excretion. Studies were repeated after an interval of 1-3 weeks in six of the subjects; the percentage oxidation in each subject was virtually unchanged between studies (coefficient of variation 8.6%). These results suggest that in vivo oxidation measurements using [13C]propionate are both reproducible and prognostically useful in disorders of propionate metabolism.

Adolescent↗
PubMed1967

The regulation of propionate oxidation in Prototheca zopfii.

1. Whole cell suspensions of Prototheca zopfii grown on propionate oxidize propionate, acrylate, malonic semialdehyde and acetate immediately, whereas acetate-grown cells only oxidize acrylate or propionate rapidly after a lag of 20-30min. This adaptation to propionate is slowed down by 8-azaguanine or p-fluorophenylalanine, and is not influenced by adding an ammonium salt or an amino acid mixture. 2. The adaptation involves induction of the enzymes of beta-oxidation of propionate. 3. A small proportion (5-8%) of the activities of propionyl-CoA dehydrogenase, beta-hydroxypropionate dehydrogenase and malonic semialdehyde dehydrogenase are consistently associated with mitochondria isolated from propionate-grown cells. 4. Such mitochondria will oxidize propionyl-CoA, beta-hydroxypropionate and malonic semialdehyde, and the respiration rates with these substrates in the presence of inorganic phosphate are ADP-dependent. 5. Mitochondria from acetate-grown cells do not contain detectable activities of the enzymes of propionate oxidation.

Acetates↗
PubMed2000

Energetics of syntrophic propionate oxidation in defined batch and chemostat cocultures.

Propionate consumption was studied in syntrophic batch and chemostat cocultures of Syntrophobacter fumaroxidans and Methanospirillum hungatei. The Gibbs free energy available for the H(2)-consuming methanogens was <-20 kJ mol of CH(4)(-1) and thus allowed the synthesis of 1/3 mol of ATP per reaction. The Gibbs free energy available for the propionate oxidizer, on the other hand, was usually >-10 kJ mol of propionate(-1). Nevertheless, the syntrophic coculture grew in the chemostat at steady-state rates of 0.04 to 0. 07 day(-1) and produced maximum biomass yields of 2.6 g mol of propionate(-1) and 7.6 g mol of CH(4)(-1) for S. fumaroxidans and M. hungatei, respectively. The energy efficiency for syntrophic growth of S. fumaroxidans, i.e., the biomass produced per unit of available Gibbs free energy was comparable to a theoretical growth yield of 5 to 12 g mol of ATP(-1). However, a lower growth efficiency was observed when sulfate served as an additional electron acceptor, suggesting inefficient energy conservation in the presence of sulfate. The maintenance Gibbs free energy determined from the maintenance coefficient of syntrophically grown S. fumaroxidans was surprisingly low (0.14 kJ h(-1) mol of biomass C(-1)) compared to the theoretical value. On the other hand, the Gibbs free-energy dissipation per mole of biomass C produced was much higher than expected. We conclude that the small Gibbs free energy available in many methanogenic environments is sufficient for syntrophic propionate oxidizers to survive on a Gibbs free energy that is much lower than that theoretically predicted.

Culture Media↗
PubMed1998

Investigation of the fumarate metabolism of the syntrophic propionate-oxidizing bacterium strain MPOB.

The growth of the syntrophic propionate-oxidizing bacterium strain MPOB in pure culture by fumarate disproportionation into carbon dioxide and succinate and by fumarate reduction with propionate, formate or hydrogen as electron donor was studied. The highest growth yield, 12.2 g dry cells/mol fumarate, was observed for growth by fumarate disproportionation. In the presence of hydrogen, formate or propionate, the growth yield was more than twice as low: 4.8, 4.6, and 5.2 g dry cells/mol fumarate, respectively. The location of enzymes that are involved in the electron transport chain during fumarate reduction in strain MPOB was analyzed. Fumarate reductase, succinate dehydrogenase, and ATPase were membrane-bound, while formate dehydrogenase and hydrogenase were loosely attached to the periplasmic side of the membrane. The cells contained cytochrome c, cytochrome b, menaquinone-6 and menaquinone-7 as possible electron carriers. Fumarate reduction with hydrogen in membranes of strain MPOB was inhibited by 2-(heptyl)-4-hydroxyquinoline-N-oxide (HOQNO). This inhibition, together with the activity of fumarate reductase with reduced 2,3-dimethyl-1,4-naphtoquinone (DMNH2) and the observation that cytochrome b of strain MPOB was oxidized by fumarate, suggested that menequinone and cytochrome b are involved in the electron transport during fumarate reduction in strain MPOB. The growth yields of fumarate reduction with hydrogen or formate as electron donor were similar to the growth yield of Wolinella succinogenes. Therefore, it can be assumed that strain MPOB gains the same amount of ATP from fumarate reduction as W. succinogenes, i. e. 0.7 mol ATP/mol fumarate. This value supports the hypothesis that syntrophic propionate-oxidizing bacteria have to invest two-thirds of an ATP via reversed electron transport in the succinate oxidation step during the oxidation of propionate. The same electron transport chain that is involved in fumarate reduction may operate in the reversed direction to drive the energetically unfavourable oxidation of succinate during syntrophic propionate oxidation since (1) cytochrome b was reduced by succinate and (2) succinate oxidation was similarly inhibited by HOQNO as fumarate reduction.

Adenosine Triphosphatases↗
PubMed1982

Accumulation and disposal of tricarboxylic acid cycle intermediates during propionate oxidation in the isolated perfused rat heart.

The role of the metabolite disposal mechanisms in the regulation of the tricarboxylic acid cycle pool size was studied in isolated perfused rat hearts oxidizing 2 mM propionate. Malate and succinate accumulated during the propionate metabolism. A further 118% increase in the malate concentration and 600% increase in the succinate concentration and a slight inhibition of the propionate uptake were observed during a subsequent KCl-induced arrest of the heart metabolizing propionate. When the mechanical activity of the heart was restored, the malate and succinate concentrations returned to the same levels as before the arrest of the heart, but the propionate uptake did not rise significantly. The mean disposal rates of the tricarboxylic acid cycle metabolites during the cardiac arrest and subsequent restoration of the activity were 1.4 and 2.4 mumol/min per g dry weight, respectively during cardiac arrest the malate carbon disposed was almost totally recovered as C3 compounds, whereas after the increase in the ATP-consumption most of it was oxidized. The result show that propionate is oxidized by heart muscle at an appreciable rate but the disposal rate of the tricarboxylic acid cycle intermediates is not tightly regulated by the cellular energy state. Although the metabolite pool size of the tricarboxylic acid cycle responds to change in the ATP consumption, the energy state appears to have a greater effect on the fate of the C3 compounds formed than on the actual rate of C4 compound disposition.

Alanine↗
PubMed1996

Purification and characterization of malate dehydrogenase from the syntrophic propionate-oxidizing bacterium strain MPOB.

Malate dehydrogenase from the syntrophic propionate-oxidizing bacterium strain MPOB was purified 42-fold. The native enzyme had an apparent molecular mass of 68 kDa and consisted of two subunits of 35 kDa. The enzyme exhibited maximum activity with oxaloacetate at pH 8.5 and 60 degrees C. The Ka for oxaloacetate was 50 microM and for NADH 30 microM. The Km values for L-malate and NAD were 4 and 1.1 mM, respectively. Substrate inhibition was found at oxaloacetate concentrations higher than 250 microM. The N-terminal amino acid sequence of the enzyme was similar to the sequences of a variety of other malate dehydrogenases from plants, animals and micro-organisms.

Amino Acid Sequence↗
PubMed1996

Purification and characterization of fumarase from the syntrophic propionate-oxidizing bacterium strain MPOB.

Fumarase from the syntrophic propionate-oxidizing bacterium strain MPOB was purified 130-fold under anoxic conditions. The native enzyme had an apparent molecular mass of 114 kDa and was composed of two subunits of 60 kDa. The enzyme exhibited maximum activity at pH 8.5 and approximately 54 degrees C. The Km values for fumarate and L-malate were 0.25 mM and 2.38 mM, respectively. Fumarase was inactivated by oxygen, but the activity could be restored by addition of Fe2+ and &beta;-mercaptoethanol under anoxic conditions. EPR spectroscopy of the purified enzyme revealed the presence of a [3Fe-4S] cluster. Under reducing conditions, only a trace amount of a [4Fe-4S] cluster was detected. Addition of fumarate resulted in a significant increase of this [4Fe-4S] signal. The N-terminal amino acid sequence showed similarity to the sequences of fumarase A and B of Escherichia coli (56%) and fumarase A of Salmonella typhimurium (63%).

Amino Acid Sequence↗
PubMed1989

Substrate disposal in metabolic disease: a comparison between rates of in vivo propionate oxidation and urinary metabolite excretion in children with methylmalonic acidemia.

The relative importance of endogenous metabolism and urinary metabolite excretion was assessed in vivo in six children with methylmalonic acidemia by examining the kinetics of the immediate precursor to methylmalonate, propionate. Total production and oxidation of propionate were measured by means of a continuous infusion of (1-13C)propionate and were compared with the urinary excretion of propionate metabolites. Propionate oxidation was substantial (mean 48.9 mumol/kg/hr +/- SD 18.0) and, in four children, exceeded urinary metabolite excretion (mean urinary excretion in all subjects 40 mumol/kg/hr +/- 25). The sum of urinary excretion and oxidation rates (88 mumol/kg/hr +/- 29) approximated the total propionate production (93.4 +/- 37.0), suggesting that these routes together constitute the major mechanisms of propionate disposal. These results suggest that propionate oxidation is an important route of disposal in methylmalonic acidemia. Variations in the relative proportions of propionate disposal through oxidation and urinary excretion may be one reason for the often poor correlation between clinical status and urinary metabolite excretion. Measurement of urinary metabolite concentration alone may not always reflect clinical status and responses to treatment accurately.

Humans↗
PubMed1989

Fermentable dietary fibers elevate urinary methylmalonate and decrease propionate oxidation in rats deprived of vitamin B-12.

This study examines the effect of dietary fiber supplements of different degrees of bacterial fermentability on biochemical indicators of vitamin B-12 deficiency in rats. Groups of rats were fed a fiber-free diet deficient in vitamin B-12 or the fiber-free diet diluted with 5% of a poorly fermentable dietary fiber (cellulose, lignin or alginic acid) or a highly fermentable fiber (pectin, guar gum or xylan). Poorly fermentable fibers had no significant effect on apparent B-12 status, whereas the highly fermentable fibers significantly increased urinary methylmalonic acid and depressed oxidation of [14C]propionate to 14CO2. Pectin consistently induced significantly greater effects than did xylan or guar gum. The data are consistent with the hypothesis that fermentable fibers stimulate bacterial propionate production and exaggerate certain biochemical indicators of B-12 deficiency. Since pectin had a more pronounced effect than did other fermentable fibers, the possibility that pectin may also interfere with B-12 absorption requires further study.

Animals↗
PubMed1996

Population dynamics of propionate-oxidizing bacteria under methanogenic and sulfidogenic conditions in anaerobic granular sludge.

Laboratory-scale upflow anaerobic sludge-bed reactors were inoculated with industrial granular sludge and fed with either propionate or propionate and sulfate. The population dynamics of the propionate-oxidizing bacteria Desulfobulbus sp. and the syntrophically growing strain SYN7 were studied in reactors by dot blot and in situ hybridization with 16S rRNA-based oligonucleotide probes.

Bacteria, Anaerobic↗
PubMed1993

[13C]propionate oxidation in wild-type and citrate synthase mutant Escherichia coli: evidence for multiple pathways of propionate utilization.

The metabolism of propionate was examined in wild-type Escherichia coli and cells lacking citrate synthase by high-resolution 13C n.m.r. Spectra of cell extracts from wild-type E. coli show that glutamate becomes highly enriched in 13C when 13C-enriched propionate is the sole carbon source. No glutamate labelling was detected when the tricarboxylic acid cycle was blocked either by deletion of citrate synthase or by inhibition of succinate dehydrogenase by malonate. The 13C fractional enrichment in glutamate C-2, C-3 and C-4 in wild-type cells was quantitatively and qualitatively different when [2-13C]propionate as opposed to [3-13C]propionate was supplied. Approximately equal labelling occurred in the C-2, C-3 and C-4 positions of glutamate when [3-13C]propionate was available, and multiplets due to carbon-carbon spin-spin coupling were observed. However, in cells supplied with [2-13C]propionate, very little 13C appeared in the glutamate C-4 position, and the remaining glutamate resonances all appeared as singlets. The unequal and non-identical labelling of glutamate in cells supplied with [2-13C]- as opposed to [3-13C]propionate is consistent with the utilization of propionate by E. coli via two pathways, oxidation of propionate to pyruvate and carboxylation of propionate to succinate. These intermediates are further metabolized to glutamate by the action of the tricarboxylic acid cycle. The existence of an organized tricarboxylic acid cycle is discussed as a consequence of the ability to block utilization of propionate in tricarboxylic acid-cycle-defective E. coli.

Acetyl Coenzyme A↗
PubMed1996

Detection and localization of syntrophic propionate-oxidizing bacteria in granular sludge by in situ hybridization using 16S rRNA-based oligonucleotide probes.

In situ hybridization with fluorescent oligonucleotides was used to detect and localize microorganisms in the granules of two lab-scale upflow anaerobic sludge blanket reactors that had been fed for several months with either sucrose or a mixture of volatile fatty acids. Sections of the granules were hybridized with 16S rRNA-targeted oligonucleotide probes for Bacteria, Archaea, specific phylogenetic groups of methanogens, and two syntrophic propionate-oxidizing strains, MPOB and KOPROP1. Cells of the syntrophic strain KOPROP1 were not detected in either type of sludge granules. Hybridizations of the sucrose-fed granules showed an outer layer of mainly bacterial microcolonies with different morphologies. More inwards of these granules, a layer of different methanogenic microcolonies mixed with large colonies of the syntrophic strain MPOB could be detected. The MPOB colonies were intertwined with hydrogen- or formate-consuming methanogens, indicating their syntrophic growth. The granules fed with volatile fatty acids showed an outer layer of mainly bacteria and then a thick layer of Methanosaeta-like methanogens mixed with a few bacteria and a layer of methanogens mixed with syntrophic MPOB microcolonies. The centers of both sludge types consisted of large cavities and methanogenic microcolonies. These results indicate a juxtapositioning of syntrophic bacteria and methanogens and provide additional evidence for a layered microbial architecture of anaerobic granular sludge.

Bacteria↗
PubMed2002

Desulfotomaculum thermobenzoicum subsp. thermosyntrophicum subsp. nov., a thermophilic, syntrophic, propionate-oxidizing, spore-forming bacterium.

From granular sludge from a laboratory-scale upflow anaerobic sludge bed reactor operated at 55 degrees C with a mixture of volatile fatty acids as feed, a novel anaerobic, moderately thermophilic, syntrophic, spore-forming bacterium, strain TPO, was enriched on propionate in co-culture with Methanobacterium thermoautotrophicum Z245. The axenic culture was obtained by using pyruvate as the sole source of carbon and energy. The cells were straight rods with pointed ends and became lens-shaped when sporulation started. The cells were slightly motile. The optimum growth temperature was 55 degrees C and growth was possible between 45 and 62 degrees C. The pH range for growth of strain TPO was 6-8, with an optimum at pH 7-7.5. Propionate was converted to acetate, CO2 and CH4 by a co-culture of strain TPO with Methanobacterium thermoautotrophicum Z245. In pure culture, strain TPO could grow fermentatively on benzoate, fumarate, H2/CO2, pyruvate and lactate. Sulphate could serve as inorganic electron acceptor when strain TPO was grown on propionate, lactate, pyruvate and H2/CO2. The G+C content was 53.7 mol%. Comparison of 16S rDNA sequences revealed that strain TPO is related to Desulfotomaculum thermobenzoicum (98%) and Desulfotomaculum thermoacetoxidans (98%). DNA-DNA hybridization revealed 88.2% reassociation between strain TPO and D. thermobenzoicum and 83.8% between strain TPO and D. thermoacetoxidans. However, both organisms differ physiologically from strain TPO and are not capable of syntrophic propionate oxidation. It is proposed that strain TPO should be classified as new subspecies of D. thermobenzoicum as D. thermobenzoicum subsp. thermosyntrophicum.

Anaerobiosis↗
PubMed1997

Propionate oxidation in Escherichia coli: evidence for operation of a methylcitrate cycle in bacteria.

Escherichia coli grew in a minimal medium on propionate as the sole carbon and energy source. Initially a lag phase of 4-7 days was observed. Cells adapted to propionate still required 1-2 days before growth commenced. Incorporation of (2-13C), (3-13C) or (2H3)propionate into alanine revealed by NMR that propionate was oxidized to pyruvate without randomisation of the carbon skeleton and excluded pathways in which the methyl group was transiently converted to a methylene group. Extracts of propionate-grown cells contained a specific enzyme that catalyses the condensation of propionyl-CoA with oxaloacetate, most probably to methylcitrate. The enzyme was purified and identified as the already-known citrate synthase II. By 2-D gel electrophoresis, the formation of a second propionate-specific enzyme with sequence similarities to isocitrate lyases was detected. The genes of both enzymes were located in a putative operon with high identities (at least 76% on the protein level) with the very recently discovered prp operon from Salmonella typhimurium. The results indicate that E. coli oxidises propionate to pyruvate via the methylcitrate cycle known from yeast. The 13C patterns of aspartate and glutamate are consistent with the further oxidation of pyruvate to acetyl-CoA. Oxaloacetate is predominantly generated via the glyoxylate cycle rather than by carboxylation of phosphoenolpyruvate.

Amino Acid Sequence↗