Two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) was used to assign the proton resonances of ferricytochrome C553 from Desulfovibrio vulgaris Hildenborough. The spin systems of 76 out of 79 amino acids were identified by J-correlation spectroscopy (COSY and HOHAHA) in H20 and D20 and correlated by nuclear Overhauser effect spectroscopy (NOESY). The proton chemical shifts are com...

Pure cultures of Desulfovibrio vulgaris or Pelobacter acetylenicus do not grow with lactate or ethanol, respectively, under obligately protonreducing conditions. However, a small part of these substrates was oxidized and molecular hydrogen was produced up to 4.2 and 3.2 kPa, respectively. During growth in syntrophic methanogenic cocultures with Methanospirillum hungatei as partner, maximum hydr...

We present a method for the measurement of hydrogenase (H(2)ase) activity in aquatic sediments. The assay is based on the H(2)ase-mediated isotopic exchange between dissolved molecular hydrogen (H(2)) and water. A slurry of sediment material is incubated with a tritiated hydrogen (HT) headspace in a glass syringe on a rotary shaker. The method includes a procedure for preparing HT from radiolab...

Interfacial reactions of cytochrome c3 at a graphite electrode were studied in a neutral medium by means of the differential pulse and cyclic voltammetry. It was found that ferricytochrome c3 yielded three cathodic peaks G, d i and Cm at potentials of —0.3 to —0.5 V (vs. Ag/AgCl reference electrode) on the voltammograms. Upon anodic polarization this protein yielded two anodic peaks Ai and An a...

Signature-tagged mutagenesis (STM) is a powerful technique that can be used to identify genes expressed by bacteria during exposure to conditions in their natural environments. To date, there have been no reports of studies in which this approach was used to study organisms of environmental, rather than pathogenic, significance. We used a mini-Tn10 transposon-bearing plasmid, pBSL180, that effi...

Cytochrome c3 (M(r) 26000) isolated from Desulfovibrio gigas is a dimeric cytochrome consisting of two identical subunits of 109 amino acids, each of which contains four haem groups. On the basis of its amino acid sequence, this cytochrome clearly belongs to the cytochrome c3 superfamily, and will be classified in class III of the c-type cytochromes as defined by Ambler [(1980) in From Cyclotro...

The rapid kinetics of bacterial U(VI) reduction and low solubility of uraninite (UO2,cr) make this process an attractive option for removing uranium from groundwater. Nevertheless, conditions that may promote or inhibit U(VI) reduction are not well-defined. Recent descriptions of Ca-UO2-CO3 complexes indicate that these species may dominate the aqueous speciation of U(VI) in many environments. ...

DdeI, a Type II restriction-modification system from the gram-negative anaerobic bacterium Desulfovibrio desulfuricans, recognizes the sequence CTNAG. The system has been cloned into E. coli in two steps. First the methylase gene was cloned into pBR322 and a derivative expressing higher levels was constructed. Then the endonuclease gene was located by Southern blot analyses; BamHI fragments lar...

The toxicity of Al to Desulfovibrio desulfuricans G20 was assessed over a period of 8 weeks in a modified lactate C medium buffered at four initial pHs (5.0, 6.5, 7.2, and 8.3) and treated with five levels of added Al (0, 0.01, 0.1, 1.0, and 10 mM). At pH 5, cell population densities decreased significantly and any effect of Al was negligible compared to that of the pH. At pHs 6.5 and 7.2, the ...

Resting cells of Desulfovibrio desulfuricans coupled the oxidation of a range of electron donors to Tc(VII) reduction. The reduced technetium was precipitated as an insoluble low-valence oxide. The optimum electron donor for the biotransformation was hydrogen, although rapid rates of reduction were also supported when formate or pyruvate was supplied to the cells. Technetium reduction was less ...