Desulfuromonas Acetoxidans Research Articles

Sulphur and sulphate reduction with acetate and propionate in an aerobic process for sulphide removal

Sulphide production rates of sulphur-and sulphate-reducing bacteria up to 50 mg per biomass support particle per day were observed in an aerated sulphide-removal reactor with polyurethane (PUR) foam as carrier material. The optimal pH and temperature for the sulphide-producing bacteria were 8.0 and 30°C respectively. Raschig rings and four types of cube-shaped PUR particles were tested as carrier materials. When using PUR particles, the sulphide production rate was always between 3% and 4% of the sulphide removal rate, dependent on the dimensions and pore size of the polyurethane support particles. With the Raschig rings this ratio was only 2% and for reactors in which no carrier materials were present it was even lower (0.6%). Media containing different mixtures of acetate, propionate, sulphur and sulphate inoculated under anoxic conditions with sludge from the aerated reactor showed the presence of acetate-degrading sulphur-reducing, but not of acetate-degrading sulphate-reducing, bacteria. With propionate as sole electron donor no degradation occurred in the presence of sulphur within 2 weeks, whereas sulphate-dependent propionate oxidation started after 5–6 days incubation. Bacteria were isolated and resembled Desulfuromonas acetoxidans and Desulfobulbus propionicus morphologically and physiologically.

Low-spin sulfite reductases: A new homologous group of non-heme iron-siroheme proteins in anaerobic bacteria

Two new low molecular weight proteins with sulfite reductase activity, isolated from Methanosarcina barkeri (DSM 800) and Desulfuromonas acetoxidans (strain 5071), were studied by EPR and optical spectroscopic techniques. Both proteins have visible spectra similar to that of the low-spin sulfite reductase of Desulfovibrio vulgaris strain Hildenborough and no band at 715 nm, characteristic of high-spin Fe3+ complexes in isobacteriochlorins is observed. EPR shows that as isolated the siroheme is in a low-spin ferric state (S = 1/2) with g-values at 2.40, 2.30 and 1.88 for the Methanosarcina barkeri enzyme and g-values at 2.44, 2.33 and 1.81 for the Desulfuromonas acetoxidans enzyme. Chemical analysis shows that both proteins contain one siroheme and one [Fe4S4] center per polypeptidic chain. These results suggest that the low molecular weight, low-spin non-heme iron siroheme proteins represent a new homologous class of sulfite reductases common to anaerobic microorganisms.

Phospholipid Ester-linked Fatty Acid Biomarkers of Acetate-oxidizing Sulphate-reducers and Other Sulphide-forming Bacteria

Summary: The phospholipid ester-linked fatty acids were examined in four Desulfobacter strains (2ac9, AcBa, 3acl0 and 4acll), a Desulfobacter-like ‘fat vibrio’ (AcKo) and Desulfotomaculum acetoxidans (5575), which are all sulphate-reducing bacteria that oxidize acetate. A thermophilic sulphate reducer, Desulfovibrio thermophilus, and two sulphur-reducing bacteria, Desulfuromonas acetoxidans (11070) and a Campylobacter-like spirillum (5175), were also studied. The Desulfobacter spp. were characterized by significant quantities of 10-methylhexadecanoic acid. Other 10-methyl fatty acids were also detected in Desulfobacter spp. No 10-methyl fatty acids were detected in the other organisms examined, supporting the use of 10-methylhexadecanoic acid as a biomarker for Desulfobacter. High levels of cyclopropyl fatty acids, including two isomers of both methylenehexadecanoic (cyl7:0) and methyleneheptadecanoic (cyl8:0) acids, were also characteristic of Desulfobacter spp. The influence of the volatile fatty acids (VFA) propionate, isobutyrate, isovalerate and 2-methylbutyrate on the lipid fatty acid distribution was studied with two Desulfobacter strains (2ac9, AcBa) and Desulfotomaculum acetoxidans. Although these sulphate reducers cannot oxidize the VFA, their presence in the acetate growth medium caused a shift in the fatty acid distribution in favour of odd-numbered and branched chains by apparent direct incorporation into the fatty acids as chain initiators. The Desulfobacter strains were distinguished from other sulphide-forming bacteria by the percentage of unsaturated and the percentage of branched fatty acids.

Phorphorylative electron transport chains lacking a cytochrome bc1 complex.

Electron transport-coupled phosphorylation with fumarate as terminal acceptor in Wolinella succinogenes yields less than 1 ATP/2 electrons. The delta mu H generated by the electron transport is 0.18 V and the H+/electron ratio is 1. The electron transport chain is made up of two dehydrogenases (hydrogenase and formate dehydrogenase) that catalyze the reduction of menaquinone, and fumarate reductase which catalyzes the oxidation of menaquinol. C-type cytochromes are not involved. The phosphorylative electron transport with sulfur as terminal acceptor in W. succinogenes or Desulfuromonas acetoxidans does not involve known quinones. The ATP yields should be even smaller than those with fumarate. Succinate oxidation by sulfur, which is a catabolic reaction in D. acetoxidans, is accomplished by reversed electron transport.

ATP-driven succinate oxidation in the catabolism of Desulfuromonas acetoxidans

The oxidation of succinate with elemental sulphur in Desulfuromonas acetoxidans was investigated using a membrane preparation of this bacterium. The following results were obtained: 1. The preparation catalyzed the oxidation of succinate with sulphur and NAD. These reactions were dependent on ATP and were abolished by the presence of protonophores or dicyclohexylcarbodiimide (DCCD). 2. The membrane preparation also catalyzed the reduction of fumarate with H2S or with NADH. These activities were not dependent on ATP and were not affected by protonophores or DCCD. 3. By extraction-reincorporation experiments it could be shown that menaquinone is involved in electron transport between H2S and fumarate and between NADH and fumarate. 4. The membrane fraction catalyzed the reduction of the water-soluble menaquinone-analogue dimethylnaphthoquinone (DMN) by succinate, H2S, or NADH, and the oxidation of DMNH2 by fumarate. These activities were not dependent on the presence of menaquinone and were not influenced by ATP. 5. The activities involving succinate oxidation or fumarate reduction were similarly sensitive to 2(n-nonyl)-4-hydroxyquinoline-N-oxide, while H2S and NADH oxidation by DMN were not affected by the inhibitor.

Mechanism of acetate oxidation to CO2 with elemental sulfur in Desulfuromonas acetoxidans

The strict anaerobe Desulfuromonas acetoxidans can oxidize acetate to CO2 with elemental sulfur as electron acceptor. 14C-labelling experiments and enzyme studies are described revealing that acetate oxidation proceeds via the citric acid cycle with the synthesis of oxaloacetate from acetate and 2 CO2 via pyruvate as anaplerotic reaction. An oxidation of acetate via one carbon unit intermediates as proposed for anaerobic bacteria fermenting acetate to 2 CO2 and 4 H2 was excluded.

Nuclear-magnetic-resonance studies of Desulfuromonas acetoxidans cytochrome c551.5 (c7).

1H nuclear magnetic resonance (NMR) spectroscopy has been used to examine cytochrome c551.5 (c7) from the sulfur reducer, Desulfuromonas acetoxidans. This protein contains three hemes. Two stable oxidation states (the fully oxidized and the fully reduced) as well as intermediate oxidation states were studied. The axial ligands of the iron were found to be neutral histidines. The redox properties of cytochrome c7 were examined and good quantitative agreement found between the NMR results and previously reported redox potential measurements. The properties of cytochrome c7 are discussed together with those of the homologous tetraheme cytochromes c3 isolate from sulfate-reducing bacteria.

Redox studies on rubredoxins from sulphate and sulphur reducing bacteria

FEBS LettersVolume 107, Issue 2 p. 419-421 Full-length articleFree Access Redox studies on rubredoxins from sulphate and sulphur reducing bacteria I. Moura, I. Moura Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, PortugalSearch for more papers by this authorJ.J.G. Moura, J.J.G. Moura Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, PortugalSearch for more papers by this authorM.H. Santos, M.H. Santos Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, PortugalSearch for more papers by this authorA.V. Xavier, Corresponding Author A.V. Xavier Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, PortugalTo whom correspondence and reprint requests should be sentSearch for more papers by this authorJ. Le Gall, J. Le Gall Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, Portugal Laboratoire de Chimie Bactèrienne, CNRS, 13274 Marseille Cedex 2, FranceSearch for more papers by this author I. Moura, I. Moura Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, PortugalSearch for more papers by this authorJ.J.G. Moura, J.J.G. Moura Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, PortugalSearch for more papers by this authorM.H. Santos, M.H. Santos Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, PortugalSearch for more papers by this authorA.V. Xavier, Corresponding Author A.V. Xavier Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, PortugalTo whom correspondence and reprint requests should be sentSearch for more papers by this authorJ. Le Gall, J. Le Gall Centro de Química Estrutural, IST, Av. Rovisco Pais, 1000 Lisboa, Portugal Laboratoire de Chimie Bactèrienne, CNRS, 13274 Marseille Cedex 2, FranceSearch for more papers by this author First published: November 15, 1979 https://doi.org/10.1016/0014-5793(79)80421-4Citations: 41AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume107, Issue2November 15, 1979Pages 419-421 ReferencesRelatedInformation

The redox properties and heme environment of cytochrome c-551.5 from Desulfuromonas acetoxidans

The environment of the three heme groups in cytochrome c-551.5 from Desulfuromonas acetoxidans was investigated by the technique of solvent perturbation difference spectroscopy. The hemeoctapeptide from cytochrome c plus added imidazole was used as a model compound for the fully exposed chromophore. The average heme exposure in both the ferric and ferrous cytochromes c-551.5 was found to be considerably greater than that previously observed for the monoheme mitochondrial cytochrome c and Prosthecochloris cytochrome c-555. Differences in the average heme exposure for ferric and ferrous cytochromes c-551.5 suggested that a change in oxidation state is accompanied by a change in conformation. A spectrophotometric redox titration of the protein yielded a sigmoidal plot of the potential versus the logarithm of the ratio of oxidized to reduced heme. The resolved plot indicated that two hemes were characterized by a E′ 0 of −177 mV and the third E′ 0 of −102 mV. Each of the resolved steps had an n value of 1 indicating that cytochrome c-551.5 transfers electrons singly.

Isolation of Desulfuromonas acetoxidans cytochrome c-551.5 from the mixed culture ‘ Chloropseudomonas ethylica’

The mixed culture ‘ Chloropseudomonas ethylica’ strain 2K has been grown on a medium which enhanced the yield of cytochrome c-551.5 from Desulfuromonas acetoxidans. The cytochrome was purified to homogeneity and an isoelectric point of 8.40 was determined. A determination of the amide content indicated that the cytochrome contains two more amides than previously reported.

Isolation and characterization of a rubredoxin and an (8Fe-8S) ferredoxin from Desulfuromonas acetoxidans

A two cluster (4Fe4S) ferredoxin and a rubredoxin have been isolated from the sulfur-reducing bacterium Desulfuromonas acetoxidans. Their amino acid compositions are reported and compared to those of other iron-sulfur proteins. The ferredoxin contains 8 cysteine residues, 8 atoms of iron and 8 atoms of labile sulfur per molecule; its minimum molecular weight is 6163. The protein exhibits an absorbance ratio of A 385 A 283 = 0.74 . Storage results in a bleaching of the chromophore; the denatured ferredoxin is reconstitutable with iron and sulfide. The instability temperature is 52°C. The rubredoxin does not differ markedly from rubredoxins from other anaerobic bacteria.

Confused History of Chloropseudomonas ethylica 2K

Abstract Chloropseudomonas ethylica 2K cultured at Brookhaven National Laboratory since 1962 has always been a mixed culture of Prosthecochloris aestuarii and Desulfuromonas acetoxidans.

Cytochrome c-551.5 ( c7) from Desulfuromonas acetoxidans

Cytochrome c-551.5 of the anaerobic sulfur-reducing bacterium Desulfuromonas acetoxidans has been purified to homogeneity and characterized. It elicits absorption bands at 551.5, 522.5 and 418 nm in the reduced form; the absorptivity ratio A α (red) A 280 nm (ox) equals 3.8 for the pure preparation. The molecular weight was estimated to be 9800 by gel filtration. Determination of the amino acid composition and analysis of the N-terminal amino acid sequence showed the cytochrome to be identical with the threehaem cytochrome c-551.5 ( c 7) isolated from the syntrophic mixed culture Chloropseudomonas ethylica strain 2K. The occurrence of multihaem cytochromes c in bacteria is discussed.

Desulfuromonas acetoxidans gen. nov. and sp. nov., a new anaerobic, sulfur-reducing, acetate-oxidizing bacterium.

Anaerobic sea or fresh water media with acetate and elemental sulfur yielded enrichments of a new type of strictly anaerobic, rod-shaped, laterally flagellated, Gram-negative bacterium. Three pure culture-strains from different sulfide-containing sea water sources were characterized in detail and are described as a new genus and species Desulfuromonas acetoxidans. The new bacterium is unable to ferment organic substances; it obtains energy for growth by anaerobic sulfur respiration. Acetate, ethanol or propanol can serve as carbon and energy source for growth; their oxidation to CO2 is stoichiometrically linked to the reduction of elemental sulfur to sulfide. Organic disulfide compounds, malate or fumarate are the only other electron acceptors used. Butanol and pyruvate are used in the presence of malate only; no other organic compounds are utilized. Biotin is required as a growth factor. The following dry weight yields per mole of substrate are obtained: in the presence of sulfur: 4.21 g on acetate, 9.77 g on ethanol; in the presence of malate: 16.5 g on acetate, 34.2 g on ethanol and 46.2 g on pyruvate. Accumulations of cells are pink; cell suspensions exhibit absorption spectra resembling those of c-type cytochromes (abs. max. at 419, 523 and 553 nm). Malate-ethanol grown cells contain a b-type cytochrome in addition. In the presence of acetate, ethanol or propanol, Desulfuromonas strains form robust growing syntrophic mixed cultures with phototrophic green sulfur bacteria.