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1.
2.
Biochemical Evidence for Formate Transfer in Syntrophic Propionate-Oxidizing Cocultures of Syntrophobacter fumaroxidans and Methanospirillum hungatei 下载免费PDF全文
Frank A. M. de Bok Maurice L. G. C. Luijten Alfons J. M. Stams 《Applied microbiology》2002,68(9):4247-4252
The hydrogenase and formate dehydrogenase levels in Syntrophobacter fumaroxidans and Methanospirillum hungatei were studied in syntrophic propionate-oxidizing cultures and compared to the levels in axenic cultures of both organisms. Cells grown syntrophically were separated from each other by Percoll gradient centrifugation. In S. fumaroxidans both formate dehydrogenase and hydrogenase levels were highest in cells which were grown syntrophically, while the formate-H2 lyase activities were comparable under the conditions tested. In M. hungatei the formate dehydrogenase and formate-H2 lyase levels were highest in cells grown syntrophically, while the hydrogenase levels in syntrophically grown cells were comparable to those in cells grown on formate. Reconstituted syntrophic cultures from axenic cultures immediately resumed syntrophic growth, and the calculated growth rates of these cultures were highest for cells which were inoculated from the axenic S. fumaroxidans cultures that exhibited the highest formate dehydrogenase activities. The results suggest that formate is the preferred electron carrier in syntrophic propionate-oxidizing cocultures of S. fumaroxidans and M. hungatei. 相似文献
3.
Human elongation factor 1α: a polymorphic and conserved multigene family with multiple chromosomal localizations 总被引:1,自引:0,他引:1
4.
Frans P. Houwen Jeannette Plokker Alfons J. M. Stams Alexander J. B. Zehnder 《Archives of microbiology》1990,155(1):52-55
Enzyme measurements were carried out with crude cell-free extracts of the propionate oxidizing coculture of Syntrophobacter wolinii and Desulfovibrio G11. Using cell-free extracts of a pure culture of Desulfovibrio G11 as a blank, most of the enzymes involved in the methylmalonyl-CoA pathway for propionate oxidation, including a propionyl-CoA: oxaloacetate transcarboxylase, were demonstrated in S. wolinii. 相似文献
5.
Purification and some properties of the methyl-CoM reductase of Methanothrix soehngenii 总被引:1,自引:0,他引:1
Mike S.M. Jetten Alfons J.M. Stams Alexander J.B. Zehnder 《FEMS microbiology letters》1990,66(1-3):183-186
Abstract The methyl-CoM reductase from Methanothrix soehngenii was purified 18-fold to apparent homogeneity with 50% recovery in three steps. The native molecular mass of the enzyme estimated by gel-fitration was 280 kDa. SDS-polyacrylamide gel electrophoresis revealed three protein bands corresponding to M r 63 900, 41 700 and 30 400 Da. The methyl-coenzyme M reductase constitutes up to 10% of the soluble cell protein. The enzyme has K m apparent values of 23 μM and 2 mM for N -7-mercaptoheptanoylthreonine phosphate (HS- HTP = component B ) and methyl-coenzyme M (CH3 CoM) respectively. At the optimum pH of 7.0 60 nmol of methane were formed per min per mg protein. 相似文献
6.
Reductive dechlorination of 1,2-dichloroethane and chloroethane by cell suspensions of methanogenic bacteria 总被引:4,自引:0,他引:4
Christof Holliger Gosse Schraa Alfons J. M. Stams Alexander J. B. Zehnder 《Biodegradation》1990,1(4):253-261
Concentrated cell suspensions of methanogenic bacteria reductively dechlorinated 1,2-dichloroethane via two reaction-mechanisms: a dihalo-elimination yielding ethylene and two hydrogenolysis reactions yielding chloroethane and ethane, consecutively. The transformation of chloroethane to ethane was inhibited by 1,2-dichloroethane. Stimulation of methanogenesis caused an increase in the amount of dechlorination products formed, whereas the opposite was found when methane formation was inhibited. Cells of Methanosarcina barkeri grown on H2/CO2 converted 1,2-dichloroethane and chloroethane at higher rates than acetate or methanol grown cells.Abbreviations BrES
2-bromoethanesulfonic acid
- CA
chloroethane
- 1,2-DCA
1,2-dichloroethane
- F430
Ni(II)tetrahydro-(12, 13)-corphin with an uroporphinoid (III) ligand skeleton 相似文献
7.
Detection of urinary TNF, IL 1, and IL 2 after local BCG immunotherapy for bladder carcinoma 总被引:2,自引:0,他引:2
Intravesical application of bacillus Calmette-Guérin (BCG) is highly active against recurrences of superficial urothelial bladder carcinoma. In an attempt to monitor the immunological effects of this therapy, we analyzed the urine of patients following the sixth intravessical instillation, to show the presence of the monokines TNF and IL 1 and the lymphokine IL 2. Within 24 hours following the instillation, all (n = 10) patients exhibited a strong increase in urinary cytokine secretion, which was significantly different from the control group (n = 10), with respect to TNF L929 biological assay (P less than 0.01), TNF sandwich-ELISA (P less than 0.01), IL 2 CTL 6 biological assay (P less than 0.05), IL 2 sandwich-ELISA (P less than 0.005), and IL 1 sandwich-ELISA (P less than 0.05), but not to the IL 1 fibroblast biological assay. The maximum urinary secretion varied between individual patients and different cytokines, but was generally found within 2 to 8 hr after the instillation. A persistent high urinary activity was demonstrated in BCG-treated patients for IL 2 in sandwich-ELISA. These results reflect the local inflammatory response to BCG and suggest an immunomodulatory mode of action against urothelial carcinoma cells. Elucidation of the possible role of each urinary cytokine against this cancer warrants further investigations. 相似文献
8.
Alfons J. M. Stams 《Antonie van Leeuwenhoek》1994,66(1-3):271-294
In methanogenic environments organic matter is degraded by associations of fermenting, acetogenic and methanogenic bacteria. Hydrogen and formate consumption, and to some extent also acetate consumption, by methanogens affects the metabolism of the other bacteria. Product formation of fermenting bacteria is shifted to more oxidized products, while acetogenic bacteria are only able to metabolize compounds when methanogens consume hydrogen and formate efficiently. These types of metabolic interaction between anaerobic bacteria is due to the fact that the oxidation of NADH and FADH2 coupled to proton or bicarbonate reduction is thermodynamically only feasible at low hydrogen and formate concentrations. Syntrophic relationships which depend on interspecies hydrogen or formate transfer were described for the degradation of e.g. fatty acids, amino acids and aromatic compounds. 相似文献
9.
Anaerobic Degradation of Propionate by a Mesophilic Acetogenic Bacterium in Coculture and Triculture with Different Methanogens 总被引:4,自引:2,他引:2 下载免费PDF全文
A mesophilic acetogenic bacterium (MPOB) oxidized propionate to acetate and CO2 in cocultures with the formate- and hydrogen-utilizing methanogens Methanospirillum hungatei and Methanobacterium formicicum. Propionate oxidation did not occur in cocultures with two Methanobrevibacter strains, which grew only with hydrogen. Tricultures consisting of MPOB, one of the Methanobrevibacter strains, and organisms which are able to convert formate into H2 plus CO2 (Desulfovibrio strain G11 or the homoacetogenic bacterium EE121) also degraded propionate. The MPOB, in the absence of methanogens, was able to couple propionate conversion to fumarate reduction. This propionate conversion was inhibited by hydrogen and by formate. Formate and hydrogen blocked the energetically unfavorable succinate oxidation to fumarate involved in propionate catabolism. Low formate and hydrogen concentrations are required for the syntrophic degradation of propionate by MPOB. In triculture with Methanospirillum hungatei and the aceticlastic Methanothrix soehngenii, propionate was degraded faster than in biculture with Methanospirillum hungatei, indicating that low acetate concentrations are favorable for propionate oxidation as well. 相似文献
10.
A male patient carrying an interstitial deletion in Xp22.3 and affected by Kallmann syndrome, X-linked ichthyosis and mental retardation, but without chondrodysplasia punctata or short stature, was investigated with molecular probes from the distal Xp22.3 region. By means of a novel probe, M115, from the relevant region, the distal deletion breakpoint was shown to be between 3.18 and 3.57 Mb from Xptel. As the patient is not affected by X-linked recessive chondrodysplasia punctata, the gene for this disease can therefore be located to within an interval of less than one megabase proximal to the pseudoautosomal boundary. If the chondrodysplasia punctata gene is associated with a CpG island, this leaves only two islands at 2760 and 3180 kb from the Xp telomere as the most promising candidate sites for this gene. 相似文献